SeongJae Park [Sun, 29 Mar 2026 15:30:49 +0000 (08:30 -0700)]
Docs/admin-guide/mm/damon/reclaim: warn commit_inputs vs param updates race
Patch series "Docs/admin-guide/mm/damon: warn commit_inputs vs other
params race".
Writing 'Y' to the commit_inputs parameter of DAMON_RECLAIM and
DAMON_LRU_SORT, and writing other parameters before the commit_inputs
request is completely processed can cause race conditions. While the
consequence can be bad, the documentation is not clearly describing that.
Add clear warnings.
The issue was discovered [1,2] by sashiko.
This patch (of 2):
DAMON_RECLAIM handles commit_inputs request inside kdamond thread,
reading the module parameters. If the user updates the module
parameters while the kdamond thread is reading those, races can happen.
To avoid this, the commit_inputs parameter shows whether it is still in
the progress, assuming users wouldn't update parameters in the middle of
the work. Some users might ignore that. Add a warning about the
behavior.
SeongJae Park [Sun, 29 Mar 2026 15:23:05 +0000 (08:23 -0700)]
mm/damon/core: use time_in_range_open() for damos quota window start
damos_adjust_quota() uses time_after_eq() to show if it is time to start a
new quota charge window, comparing the current jiffies and the scheduled
next charge window start time. If it is, the next charge window start
time is updated and the new charge window starts.
The time check and next window start time update is skipped while the
scheme is deactivated by the watermarks. Let's suppose the deactivation
is kept more than LONG_MAX jiffies (assuming CONFIG_HZ of 250, more than
99 days in 32 bit systems and more than one billion years in 64 bit
systems), resulting in having the jiffies larger than the next charge
window start time + LONG_MAX. Then, the time_after_eq() call can return
false until another LONG_MAX jiffies are passed.
This means the scheme can continue working after being reactivated by the
watermarks. But, soon, the quota will be exceeded and the scheme will
again effectively stop working until the next charge window starts.
Because the current charge window is extended to up to LONG_MAX jiffies,
however, it will look like it stopped unexpectedly and indefinitely, from
the user's perspective.
SeongJae Park [Sun, 29 Mar 2026 04:39:00 +0000 (21:39 -0700)]
mm/damon/core: validate damos_quota_goal->nid for node_memcg_{used,free}_bp
Users can set damos_quota_goal->nid with arbitrary value for
node_memcg_{used,free}_bp. But DAMON core is using those for NODE-DATA()
without a validation of the value. This can result in out of bounds
memory access. The issue can actually triggered using DAMON user-space
tool (damo), like below.
Fix this issue by adding the validation of the given node id. If an
invalid node id is given, it returns 0% for used memory ratio, and 100%
for free memory ratio.
Link: https://lore.kernel.org/20260329043902.46163-3-sj@kernel.org Fixes: b74a120bcf50 ("mm/damon/core: implement DAMOS_QUOTA_NODE_MEMCG_USED_BP") Signed-off-by: SeongJae Park <sj@kernel.org> Cc: <stable@vger.kernel.org> # 6.19.x Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
SeongJae Park [Sun, 29 Mar 2026 04:38:59 +0000 (21:38 -0700)]
mm/damon/core: validate damos_quota_goal->nid for node_mem_{used,free}_bp
Patch series "mm/damon/core: validate damos_quota_goal->nid".
node_mem[cg]_{used,free}_bp DAMOS quota goals receive the node id. The
node id is used for si_meminfo_node() and NODE_DATA() without proper
validation. As a result, privileged users can trigger an out of bounds
memory access using DAMON_SYSFS. Fix the issues.
The issue was originally reported [1] with a fix by another author. The
original author announced [2] that they will stop working including the
fix that was still in the review stage. Hence I'm restarting this.
This patch (of 2):
Users can set damos_quota_goal->nid with arbitrary value for
node_mem_{used,free}_bp. But DAMON core is using those for
si_meminfo_node() without the validation of the value. This can result in
out of bounds memory access. The issue can actually triggered using DAMON
user-space tool (damo), like below.
Fix this issue by adding the validation of the given node. If an invalid
node id is given, it returns 0% for used memory ratio, and 100% for free
memory ratio.
Jackie Liu [Tue, 31 Mar 2026 10:15:53 +0000 (18:15 +0800)]
mm/damon/stat: fix memory leak on damon_start() failure in damon_stat_start()
Destroy the DAMON context and reset the global pointer when damon_start()
fails. Otherwise, the context allocated by damon_stat_build_ctx() is
leaked, and the stale damon_stat_context pointer will be overwritten on
the next enable attempt, making the old allocation permanently
unreachable.
Link: https://lore.kernel.org/20260331101553.88422-1-liu.yun@linux.dev Fixes: 369c415e6073 ("mm/damon: introduce DAMON_STAT module") Signed-off-by: Jackie Liu <liuyun01@kylinos.cn> Reviewed-by: SeongJae Park <sj@kernel.org> Cc: <stable@vger.kernel.org> # 6.17.x Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
SeongJae Park [Fri, 27 Mar 2026 23:33:15 +0000 (16:33 -0700)]
mm/damon/core: fix damos_walk() vs kdamond_fn() exit race
When kdamond_fn() main loop is finished, the function cancels remaining
damos_walk() request and unset the damon_ctx->kdamond so that API callers
and API functions themselves can show the context is terminated.
damos_walk() adds the caller's request to the queue first. After that, it
shows if the kdamond of the damon_ctx is still running (damon_ctx->kdamond
is set). Only if the kdamond is running, damos_walk() starts waiting for
the kdamond's handling of the newly added request.
The damos_walk() requests registration and damon_ctx->kdamond unset are
protected by different mutexes, though. Hence, damos_walk() could race
with damon_ctx->kdamond unset, and result in deadlocks.
For example, let's suppose kdamond successfully finished the damow_walk()
request cancelling. Right after that, damos_walk() is called for the
context. It registers the new request, and shows the context is still
running, because damon_ctx->kdamond unset is not yet done. Hence the
damos_walk() caller starts waiting for the handling of the request.
However, the kdamond is already on the termination steps, so it never
handles the new request. As a result, the damos_walk() caller thread
infinitely waits.
Fix this by introducing another damon_ctx field, namely
walk_control_obsolete. It is protected by the
damon_ctx->walk_control_lock, which protects damos_walk() request
registration. Initialize (unset) it in kdamond_fn() before letting
damon_start() returns and set it just before the cancelling of the
remaining damos_walk() request is executed. damos_walk() reads the
obsolete field under the lock and avoids adding a new request.
After this change, only requests that are guaranteed to be handled or
cancelled are registered. Hence the after-registration DAMON context
termination check is no longer needed. Remove it together.
SeongJae Park [Fri, 27 Mar 2026 23:33:14 +0000 (16:33 -0700)]
mm/damon/core: fix damon_call() vs kdamond_fn() exit race
Patch series "mm/damon/core: fix damon_call()/damos_walk() vs kdmond exit
race".
damon_call() and damos_walk() can leak memory and/or deadlock when they
race with kdamond terminations. Fix those.
This patch (of 2);
When kdamond_fn() main loop is finished, the function cancels all
remaining damon_call() requests and unset the damon_ctx->kdamond so that
API callers and API functions themselves can know the context is
terminated. damon_call() adds the caller's request to the queue first.
After that, it shows if the kdamond of the damon_ctx is still running
(damon_ctx->kdamond is set). Only if the kdamond is running, damon_call()
starts waiting for the kdamond's handling of the newly added request.
The damon_call() requests registration and damon_ctx->kdamond unset are
protected by different mutexes, though. Hence, damon_call() could race
with damon_ctx->kdamond unset, and result in deadlocks.
For example, let's suppose kdamond successfully finished the damon_call()
requests cancelling. Right after that, damon_call() is called for the
context. It registers the new request, and shows the context is still
running, because damon_ctx->kdamond unset is not yet done. Hence the
damon_call() caller starts waiting for the handling of the request.
However, the kdamond is already on the termination steps, so it never
handles the new request. As a result, the damon_call() caller threads
infinitely waits.
Fix this by introducing another damon_ctx field, namely
call_controls_obsolete. It is protected by the
damon_ctx->call_controls_lock, which protects damon_call() requests
registration. Initialize (unset) it in kdamond_fn() before letting
damon_start() returns and set it just before the cancelling of remaining
damon_call() requests is executed. damon_call() reads the obsolete field
under the lock and avoids adding a new request.
After this change, only requests that are guaranteed to be handled or
cancelled are registered. Hence the after-registration DAMON context
termination check is no longer needed. Remove it together.
Note that the deadlock will not happen when damon_call() is called for
repeat mode request. In tis case, damon_call() returns instead of waiting
for the handling when the request registration succeeds and it shows the
kdamond is running. However, if the request also has dealloc_on_cancel,
the request memory would be leaked.
mm: zswap: tie per-CPU acomp_ctx lifetime to the pool
Currently, per-CPU acomp_ctx are allocated on pool creation and/or CPU
hotplug, and destroyed on pool destruction or CPU hotunplug. This
complicates the lifetime management to save memory while a CPU is
offlined, which is not very common.
Simplify lifetime management by allocating per-CPU acomp_ctx once on pool
creation (or CPU hotplug for CPUs onlined later), and keeping them
allocated until the pool is destroyed.
Refactor cleanup code from zswap_cpu_comp_dead() into acomp_ctx_free() to
be used elsewhere.
The main benefit of using the CPU hotplug multi state instance startup
callback to allocate the acomp_ctx resources is that it prevents the cores
from being offlined until the multi state instance addition call returns.
From Documentation/core-api/cpu_hotplug.rst:
"The node list add/remove operations and the callback invocations are
serialized against CPU hotplug operations."
Furthermore, zswap_[de]compress() cannot contend with
zswap_cpu_comp_prepare() because:
- During pool creation/deletion, the pool is not in the zswap_pools
list.
- During CPU hot[un]plug, the CPU is not yet online, as Yosry pointed
out. zswap_cpu_comp_prepare() will be run on a control CPU,
since CPUHP_MM_ZSWP_POOL_PREPARE is in the PREPARE section of "enum
cpuhp_state".
In both these cases, any recursions into zswap reclaim from
zswap_cpu_comp_prepare() will be handled by the old pool.
The above two observations enable the following simplifications:
1) zswap_cpu_comp_prepare():
a) acomp_ctx mutex locking:
If the process gets migrated while zswap_cpu_comp_prepare() is
running, it will complete on the new CPU. In case of failures, we
pass the acomp_ctx pointer obtained at the start of
zswap_cpu_comp_prepare() to acomp_ctx_free(), which again, can
only undergo migration. There appear to be no contention
scenarios that might cause inconsistent values of acomp_ctx's
members. Hence, it seems there is no need for
mutex_lock(&acomp_ctx->mutex) in zswap_cpu_comp_prepare().
b) acomp_ctx mutex initialization:
Since the pool is not yet on zswap_pools list, we don't need to
initialize the per-CPU acomp_ctx mutex in
zswap_pool_create(). This has been restored to occur in
zswap_cpu_comp_prepare().
c) Subsequent CPU offline-online transitions:
zswap_cpu_comp_prepare() checks upfront if acomp_ctx->acomp is
valid. If so, it returns success. This should handle any CPU
hotplug online-offline transitions after pool creation is done.
2) CPU offline vis-a-vis zswap ops:
Let's suppose the process is migrated to another CPU before the
current CPU is dysfunctional. If zswap_[de]compress() holds the
acomp_ctx->mutex lock of the offlined CPU, that mutex will be
released once it completes on the new CPU. Since there is no
teardown callback, there is no possibility of UAF.
3) Pool creation/deletion and process migration to another CPU:
During pool creation/deletion, the pool is not in the zswap_pools
list. Hence it cannot contend with zswap ops on that CPU. However,
the process can get migrated.
a) Pool creation --> zswap_cpu_comp_prepare()
--> process migrated:
* Old CPU offline: no-op.
* zswap_cpu_comp_prepare() continues
to run on the new CPU to finish
allocating acomp_ctx resources for
the offlined CPU.
b) Pool deletion --> acomp_ctx_free()
--> process migrated:
* Old CPU offline: no-op.
* acomp_ctx_free() continues
to run on the new CPU to finish
de-allocating acomp_ctx resources
for the offlined CPU.
4) Pool deletion vis-a-vis CPU onlining:
The call to cpuhp_state_remove_instance() cannot race with
zswap_cpu_comp_prepare() because of hotplug synchronization.
The current acomp_ctx_get_cpu_lock()/acomp_ctx_put_unlock() are deleted.
Instead, zswap_[de]compress() directly call
mutex_[un]lock(&acomp_ctx->mutex).
The per-CPU memory cost of not deleting the acomp_ctx resources upon CPU
offlining, and only deleting them when the pool is destroyed, is 8.28 KB
on x86_64. This cost is only paid when a CPU is offlined, until it is
onlined again.
Link: https://lore.kernel.org/20260331183351.29844-3-kanchanapsridhar2026@gmail.com Co-developed-by: Kanchana P. Sridhar <kanchanapsridhar2026@gmail.com> Signed-off-by: Kanchana P. Sridhar <kanchanapsridhar2026@gmail.com> Signed-off-by: Kanchana P Sridhar <kanchana.p.sridhar@intel.com> Acked-by: Yosry Ahmed <yosry@kernel.org> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Herbert Xu <herbert@gondor.apana.org.au> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Sergey Senozhatsky <senozhatsky@chromium.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: zswap: remove redundant checks in zswap_cpu_comp_dead()
Patch series "zswap pool per-CPU acomp_ctx simplifications", v3.
This patchset first removes redundant checks on the acomp_ctx and its
"req" member in zswap_cpu_comp_dead().
Next, it persists the zswap pool's per-CPU acomp_ctx resources to last
until the pool is destroyed. It then simplifies the per-CPU acomp_ctx
mutex locking in zswap_compress()/zswap_decompress().
Code comments added after allocation and before checking to deallocate the
per-CPU acomp_ctx's members, based on expected crypto API return values
and zswap changes this patchset makes.
Patch 2 is an independent submission of patch 23 from [1], to
facilitate merging.
This patch (of 2):
There are presently redundant checks on the per-CPU acomp_ctx and it's
"req" member in zswap_cpu_comp_dead(): redundant because they are
inconsistent with zswap_pool_create() handling of failure in allocating
the acomp_ctx, and with the expected NULL return value from the
acomp_request_alloc() API when it fails to allocate an acomp_req.
Fix these by converting to them to be NULL checks.
Add comments in zswap_cpu_comp_prepare() clarifying the expected return
values of the crypto_alloc_acomp_node() and acomp_request_alloc() API.
Hao Ge [Tue, 31 Mar 2026 08:13:12 +0000 (16:13 +0800)]
mm/alloc_tag: clear codetag for pages allocated before page_ext initialization
Due to initialization ordering, page_ext is allocated and initialized
relatively late during boot. Some pages have already been allocated and
freed before page_ext becomes available, leaving their codetag
uninitialized.
A clear example is in init_section_page_ext(): alloc_page_ext() calls
kmemleak_alloc(). If the slab cache has no free objects, it falls back to
the buddy allocator to allocate memory. However, at this point page_ext
is not yet fully initialized, so these newly allocated pages have no
codetag set. These pages may later be reclaimed by KASAN, which causes
the warning to trigger when they are freed because their codetag ref is
still empty.
Use a global array to track pages allocated before page_ext is fully
initialized. The array size is fixed at 8192 entries, and will emit a
warning if this limit is exceeded. When page_ext initialization
completes, set their codetag to empty to avoid warnings when they are
freed later.
This warning is only observed with CONFIG_MEM_ALLOC_PROFILING_DEBUG=Y and
mem_profiling_compressed disabled:
mm/vmscan: prevent MGLRU reclaim from pinning address space
When shrinking lruvec, MGLRU pins address space before walking it. This
is excessive since all it needs for walking the page range is a stable
mm_struct to be able to take and release mmap_read_lock and a stable
mm->mm_mt tree to walk. This address space pinning results in delays when
releasing the memory of a dying process. This also prevents mm reapers
(both in-kernel oom-reaper and userspace process_mrelease()) from doing
their job during MGLRU scan because they check task_will_free_mem() which
will yield negative result due to the elevated mm->mm_users.
This affects the system in the sense that if the MM of the killed
process is being reclaimed by kswapd then reapers won't be able to reap
it. Even the process itself (which might have higher-priority than
kswapd) will not free its memory until kswapd drops the last reference.
IOW, we delay freeing the memory because kswapd is reclaiming it. In
Android the visible result for us is that process_mrelease() (userspace
reaper) skips MM in such cases and we see process memory not released
for an unusually long time (secs).
Replace unnecessary address space pinning with mm_struct pinning by
replacing mmget/mmput with mmgrab/mmdrop calls. mm_mt is contained within
mm_struct itself, therefore it won't be freed as long as mm_struct is
stable and it won't change during the walk because mmap_read_lock is being
held.
Link: https://lore.kernel.org/20260322070843.941997-1-surenb@google.com Fixes: bd74fdaea146 ("mm: multi-gen LRU: support page table walks") Signed-off-by: Suren Baghdasaryan <surenb@google.com> Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: David Hildenbrand <david@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Qi Zheng <zhengqi.arch@bytedance.com> Cc: Shakeel Butt <shakeel.butt@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Wei Xu <weixugc@google.com> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Yu Zhao <yuzhao@google.com> Cc: Kalesh Singh <kaleshsingh@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pasha Tatashin [Fri, 27 Mar 2026 03:33:34 +0000 (03:33 +0000)]
liveupdate: defer file handler module refcounting to active sessions
Stop pinning modules indefinitely upon file handler registration.
Instead, dynamically increment the module reference count only when a live
update session actively uses the file handler (e.g., during preservation
or deserialization), and release it when the session ends.
This allows modules providing live update handlers to be gracefully
unloaded when no live update is in progress.
Link: https://lore.kernel.org/20260327033335.696621-11-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org> Cc: David Matlack <dmatlack@google.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Samiullah Khawaja <skhawaja@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pasha Tatashin [Fri, 27 Mar 2026 03:33:33 +0000 (03:33 +0000)]
liveupdate: make unregister functions return void
Change liveupdate_unregister_file_handler and liveupdate_unregister_flb to
return void instead of an error code. This follows the design principle
that unregistration during module unload should not fail, as the unload
cannot be stopped at that point.
Link: https://lore.kernel.org/20260327033335.696621-10-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org> Cc: David Matlack <dmatlack@google.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Samiullah Khawaja <skhawaja@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pasha Tatashin [Fri, 27 Mar 2026 03:33:32 +0000 (03:33 +0000)]
liveupdate: remove liveupdate_test_unregister()
Now that file handler unregistration automatically unregisters all
associated file handlers (FLBs), the liveupdate_test_unregister() function
is no longer needed. Remove it along with its usages and declarations.
Link: https://lore.kernel.org/20260327033335.696621-9-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org> Cc: David Matlack <dmatlack@google.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Samiullah Khawaja <skhawaja@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pasha Tatashin [Fri, 27 Mar 2026 03:33:31 +0000 (03:33 +0000)]
liveupdate: auto unregister FLBs on file handler unregistration
To ensure that unregistration is always successful and doesn't leave
dangling resources, introduce auto-unregistration of FLBs: when a file
handler is unregistered, all FLBs associated with it are automatically
unregistered.
Introduce a new helper luo_flb_unregister_all() which unregisters all FLBs
linked to the given file handler.
Link: https://lore.kernel.org/20260327033335.696621-8-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org> Cc: David Matlack <dmatlack@google.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Samiullah Khawaja <skhawaja@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pasha Tatashin [Fri, 27 Mar 2026 03:33:30 +0000 (03:33 +0000)]
liveupdate: remove luo_session_quiesce()
Now that FLB module references are handled dynamically during active
sessions, we can safely remove the luo_session_quiesce() and
luo_session_resume() mechanism.
Link: https://lore.kernel.org/20260327033335.696621-7-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org> Cc: David Matlack <dmatlack@google.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Samiullah Khawaja <skhawaja@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pasha Tatashin [Fri, 27 Mar 2026 03:33:29 +0000 (03:33 +0000)]
liveupdate: defer FLB module refcounting to active sessions
Stop pinning modules indefinitely upon FLB registration. Instead,
dynamically take a module reference when the FLB is actively used in a
session (e.g., during preserve and retrieve) and release it when the
session concludes.
This allows modules providing FLB operations to be cleanly unloaded when
not in active use by the live update orchestrator.
Link: https://lore.kernel.org/20260327033335.696621-6-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Reviewed-by: Samiullah Khawaja <skhawaja@google.com> Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org> Cc: David Matlack <dmatlack@google.com> Cc: Mike Rapoport <rppt@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pasha Tatashin [Fri, 27 Mar 2026 03:33:28 +0000 (03:33 +0000)]
liveupdate: protect FLB lists with luo_register_rwlock
Because liveupdate FLB objects will soon drop their persistent module
references when registered, list traversals must be protected against
concurrent module unloading.
To provide this protection, utilize the global luo_register_rwlock. It
protects the global registry of FLBs and the handler's specific list of
FLB dependencies.
Read locks are used during concurrent list traversals (e.g., during
preservation and serialization). Write locks are taken during
registration and unregistration.
Link: https://lore.kernel.org/20260327033335.696621-5-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org> Cc: David Matlack <dmatlack@google.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Samiullah Khawaja <skhawaja@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pasha Tatashin [Fri, 27 Mar 2026 03:33:27 +0000 (03:33 +0000)]
liveupdate: protect file handler list with rwsem
Because liveupdate file handlers will no longer hold a module reference
when registered, we must ensure that the access to the handler list is
protected against concurrent module unloading.
Utilize the global luo_register_rwlock to protect the global registry of
file handlers. Read locks are taken during list traversals in
luo_preserve_file() and luo_file_deserialize(). Write locks are taken
during registration and unregistration.
Link: https://lore.kernel.org/20260327033335.696621-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org> Cc: David Matlack <dmatlack@google.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Samiullah Khawaja <skhawaja@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pasha Tatashin [Fri, 27 Mar 2026 03:33:26 +0000 (03:33 +0000)]
liveupdate: synchronize lazy initialization of FLB private state
The luo_flb_get_private() function, which is responsible for lazily
initializing the private state of FLB objects, can be called concurrently
from multiple threads. This creates a data race on the 'initialized' flag
and can lead to multiple executions of mutex_init() and INIT_LIST_HEAD()
on the same memory.
Introduce a static spinlock (luo_flb_init_lock) local to the function to
synchronize the initialization path. Use smp_load_acquire() and
smp_store_release() for memory ordering between the fast path and the slow
path.
Link: https://lore.kernel.org/20260327033335.696621-3-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Reviewed-by: Pratyush Yadav <pratyush@kernel.org> Cc: David Matlack <dmatlack@google.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Samiullah Khawaja <skhawaja@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pasha Tatashin [Fri, 27 Mar 2026 03:33:25 +0000 (03:33 +0000)]
liveupdate: safely print untrusted strings
Patch series "liveupdate: Fix module unloading and unregister API", v3.
This patch series addresses an issue with how LUO handles module reference
counting and unregistration during a module unload (e.g., via rmmod).
Currently, modules that register live update file handlers are pinned for
the entire duration they are registered. This prevents the modules from
being unloaded gracefully, even when no live update session is in
progress.
Furthermore, if a module is forcefully unloaded, the unregistration
functions return an error (e.g. -EBUSY) if a session is active, which is
ignored by the kernel's module unload path, leaving dangling pointers in
the LUO global lists.
To resolve these issues, this series introduces the following changes:
1. Adds a global read-write semaphore (luo_register_rwlock) to protect
the registration lists for both file handlers and FLBs.
2. Reduces the scope of module reference counting for file handlers and
FLBs. Instead of pinning modules indefinitely upon registration,
references are now taken only when they are actively used in a live
update session (e.g., during preservation, retrieval, or
deserialization).
3. Removes the global luo_session_quiesce() mechanism since module
unload behavior now handles active sessions implicitly.
4. Introduces auto-unregistration of FLBs during file handler
unregistration to prevent leaving dangling resources.
5. Changes the unregistration functions to return void instead of
an error code.
6. Fixes a data race in luo_flb_get_private() by introducing a spinlock
for thread-safe lazy initialization.
7. Strengthens security by using %.*s when printing untrusted deserialized
compatible strings and session names to prevent out-of-bounds reads.
This patch (of 10):
Deserialized strings from KHO data (such as file handler compatible
strings and session names) are provided by the previous kernel and might
not be null-terminated if the data is corrupted or maliciously crafted.
When printing these strings in error messages, use the %.*s format
specifier with the maximum buffer size to prevent out-of-bounds reads into
adjacent kernel memory.
Baolin Wang [Fri, 27 Mar 2026 10:21:08 +0000 (18:21 +0800)]
mm: vmscan: fix dirty folios throttling on cgroup v1 for MGLRU
The balance_dirty_pages() won't do the dirty folios throttling on
cgroupv1. See commit 9badce000e2c ("cgroup, writeback: don't enable
cgroup writeback on traditional hierarchies").
Moreover, after commit 6b0dfabb3555 ("fs: Remove aops->writepage"), we no
longer attempt to write back filesystem folios through reclaim.
On large memory systems, the flusher may not be able to write back quickly
enough. Consequently, MGLRU will encounter many folios that are already
under writeback. Since we cannot reclaim these dirty folios, the system
may run out of memory and trigger the OOM killer.
Hence, for cgroup v1, let's throttle reclaim after waking up the flusher,
which is similar to commit 81a70c21d917 ("mm/cgroup/reclaim: fix dirty
pages throttling on cgroup v1"), to avoid unnecessary OOM.
The following test program can easily reproduce the OOM issue. With this
patch applied, the test passes successfully.
Pasha Tatashin [Thu, 26 Mar 2026 16:39:43 +0000 (16:39 +0000)]
selftests: liveupdate: add test for double preservation
Verify that a file can only be preserved once across all active sessions.
Attempting to preserve it a second time, whether in the same or a
different session, should fail with EBUSY.
Link: https://lore.kernel.org/20260326163943.574070-4-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Reviewed-by: Samiullah Khawaja <skhawaja@google.com> Cc: David Matlack <dmatlack@google.com> Cc: Pratyush Yadav <pratyush@kernel.org> Cc: Shuah Khan <shuah@kernel.org> Cc: Christian Brauner <brauner@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pasha Tatashin [Thu, 26 Mar 2026 16:39:42 +0000 (16:39 +0000)]
memfd: implement get_id for memfd_luo
Memfds are identified by their underlying inode. Implement get_id for
memfd_luo to return the inode pointer. This prevents the same memfd from
being managed twice by LUO if the same inode is pointed by multiple file
objects.
Link: https://lore.kernel.org/20260326163943.574070-3-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Reviewed-by: Pratyush Yadav (Google) <pratyush@kernel.org> Cc: David Matlack <dmatlack@google.com> Cc: Mike Rapoport (Microsoft) <rppt@kernel.org> Cc: Samiullah Khawaja <skhawaja@google.com> Cc: Shuah Khan <shuah@kernel.org> Cc: Christian Brauner <brauner@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Pasha Tatashin [Thu, 26 Mar 2026 16:39:41 +0000 (16:39 +0000)]
liveupdate: prevent double management of files
Patch series "liveupdate: prevent double preservation", v4.
Currently, LUO does not prevent the same file from being managed twice
across different active sessions.
Because LUO preserves files of absolutely different types: memfd, and
upcoming vfiofd [1], iommufd [2], guestmefd (and possible kvmfd/cpufd).
There is no common private data or guarantee on how to prevent that the
same file is not preserved twice beside using inode or some slower and
expensive method like hashtables.
This patch (of 4)
Currently, LUO does not prevent the same file from being managed twice
across different active sessions.
Use a global xarray luo_preserved_files to keep track of file identifiers
being preserved by LUO. Update luo_preserve_file() to check and insert
the file identifier into this xarray when it is preserved, and erase it in
luo_file_unpreserve_files() when it is released.
To allow handlers to define what constitutes a "unique" file (e.g.,
different struct file objects pointing to the same hardware resource), add
a get_id() callback to struct liveupdate_file_ops. If not provided, the
default identifier is the struct file pointer itself.
This ensures that the same file (or resource) cannot be managed by
multiple sessions. If another session attempts to preserve an already
managed file, it will now fail with -EBUSY.
Breno Leitao [Mon, 16 Mar 2026 11:54:36 +0000 (04:54 -0700)]
kho: document kexec-metadata tracking feature
Add documentation for the kexec-metadata feature that tracks the previous
kernel version and kexec boot count across kexec reboots. This helps
diagnose bugs that only reproduce when kexecing from specific kernel
versions.
Link: https://lore.kernel.org/20260316-kho-v9-6-ed6dcd951988@debian.org Signed-off-by: Breno Leitao <leitao@debian.org> Suggested-by: Mike Rapoport <rppt@kernel.org> Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Reviewed-by: Pratyush Yadav <pratyush@kernel.org> Cc: Alexander Graf <graf@amazon.com> Cc: David Hildenbrand <david@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: SeongJae Park <sj@kernel.org> Cc: Shuah Khan <skhan@linuxfoundation.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Vlastimil Babka <vbabka@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Breno Leitao [Mon, 16 Mar 2026 11:54:35 +0000 (04:54 -0700)]
kho: kexec-metadata: track previous kernel chain
Use Kexec Handover (KHO) to pass the previous kernel's version string and
the number of kexec reboots since the last cold boot to the next kernel,
and print it at boot time.
Example output:
[ 0.000000] KHO: exec from: 6.19.0-rc4-next-20260107 (count 1)
Motivation
==========
Bugs that only reproduce when kexecing from specific kernel versions are
difficult to diagnose. These issues occur when a buggy kernel kexecs into
a new kernel, with the bug manifesting only in the second kernel.
Recent examples include the following commits:
* commit eb2266312507 ("x86/boot: Fix page table access in
5-level to 4-level paging transition")
* commit 77d48d39e991 ("efistub/tpm: Use ACPI reclaim memory
for event log to avoid corruption")
* commit 64b45dd46e15 ("x86/efi: skip memattr table on kexec
boot")
As kexec-based reboots become more common, these version-dependent bugs
are appearing more frequently. At scale, correlating crashes to the
previous kernel version is challenging, especially when issues only occur
in specific transition scenarios.
Implementation
==============
The kexec metadata is stored as a plain C struct (struct
kho_kexec_metadata) rather than FDT format, for simplicity and direct
field access. It is registered via kho_add_subtree() as a separate
subtree, keeping it independent from the core KHO ABI. This design
choice:
- Keeps the core KHO ABI minimal and stable
- Allows the metadata format to evolve independently
- Avoids requiring version bumps for all KHO consumers (LUO, etc.)
when the metadata format changes
The struct kho_kexec_metadata contains two fields:
- previous_release: The kernel version that initiated the kexec
- kexec_count: Number of kexec boots since last cold boot
On cold boot, kexec_count starts at 0 and increments with each kexec. The
count helps identify issues that only manifest after multiple consecutive
kexec reboots.
[leitao@debian.org: call kho_kexec_metadata_init() for both boot paths] Link: https://lore.kernel.org/all/20260309-kho-v8-5-c3abcf4ac750@debian.org/ Link: https://lore.kernel.org/20260409-kho_fix_merge_issue-v1-1-710c84ceaa85@debian.org Link: https://lore.kernel.org/20260316-kho-v9-5-ed6dcd951988@debian.org Signed-off-by: Breno Leitao <leitao@debian.org> Acked-by: SeongJae Park <sj@kernel.org> Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Reviewed-by: Pratyush Yadav <pratyush@kernel.org> Cc: Alexander Graf <graf@amazon.com> Cc: David Hildenbrand <david@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Shuah Khan <skhan@linuxfoundation.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Vlastimil Babka <vbabka@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Breno Leitao [Mon, 16 Mar 2026 11:54:34 +0000 (04:54 -0700)]
kho: fix kho_in_debugfs_init() to handle non-FDT blobs
kho_in_debugfs_init() calls fdt_totalsize() to determine blob sizes, which
assumes all blobs are FDTs. This breaks for non-FDT blobs like struct
kho_kexec_metadata.
Fix this by reading the "blob-size" property from the FDT (persisted by
kho_add_subtree()) instead of calling fdt_totalsize(). Also rename local
variables from fdt_phys/sub_fdt to blob_phys/blob for consistency with the
non-FDT-specific naming.
Link: https://lore.kernel.org/20260316-kho-v9-4-ed6dcd951988@debian.org Signed-off-by: Breno Leitao <leitao@debian.org> Reviewed-by: Pratyush Yadav <pratyush@kernel.org> Cc: Alexander Graf <graf@amazon.com> Cc: David Hildenbrand <david@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Rapoport (Microsoft) <rppt@kernel.org> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: SeongJae Park <sj@kernel.org> Cc: Shuah Khan <skhan@linuxfoundation.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Vlastimil Babka <vbabka@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Breno Leitao [Mon, 16 Mar 2026 11:54:33 +0000 (04:54 -0700)]
kho: persist blob size in KHO FDT
kho_add_subtree() accepts a size parameter but only forwards it to
debugfs. The size is not persisted in the KHO FDT, so it is lost across
kexec. This makes it impossible for the incoming kernel to determine the
blob size without understanding the blob format.
Store the blob size as a "blob-size" property in the KHO FDT alongside the
"preserved-data" physical address. This allows the receiving kernel to
recover the size for any blob regardless of format.
Also extend kho_retrieve_subtree() with an optional size output parameter
so callers can learn the blob size without needing to understand the blob
format. Update all callers to pass NULL for the new parameter.
Link: https://lore.kernel.org/20260316-kho-v9-3-ed6dcd951988@debian.org Signed-off-by: Breno Leitao <leitao@debian.org> Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Reviewed-by: Pratyush Yadav <pratyush@kernel.org> Cc: Alexander Graf <graf@amazon.com> Cc: David Hildenbrand <david@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: SeongJae Park <sj@kernel.org> Cc: Shuah Khan <skhan@linuxfoundation.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Vlastimil Babka <vbabka@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Breno Leitao [Mon, 16 Mar 2026 11:54:32 +0000 (04:54 -0700)]
kho: rename fdt parameter to blob in kho_add/remove_subtree()
Since kho_add_subtree() now accepts arbitrary data blobs (not just FDTs),
rename the parameter from 'fdt' to 'blob' to better reflect its purpose.
Apply the same rename to kho_remove_subtree() for consistency.
Also rename kho_debugfs_fdt_add() and kho_debugfs_fdt_remove() to
kho_debugfs_blob_add() and kho_debugfs_blob_remove() respectively, with
the same parameter rename from 'fdt' to 'blob'.
Link: https://lore.kernel.org/20260316-kho-v9-2-ed6dcd951988@debian.org Signed-off-by: Breno Leitao <leitao@debian.org> Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Reviewed-by: Pratyush Yadav <pratyush@kernel.org> Cc: Alexander Graf <graf@amazon.com> Cc: David Hildenbrand <david@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: SeongJae Park <sj@kernel.org> Cc: Shuah Khan <skhan@linuxfoundation.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Vlastimil Babka <vbabka@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Breno Leitao [Mon, 16 Mar 2026 11:54:31 +0000 (04:54 -0700)]
kho: add size parameter to kho_add_subtree()
Patch series "kho: history: track previous kernel version and kexec boot
count", v9.
Use Kexec Handover (KHO) to pass the previous kernel's version string and
the number of kexec reboots since the last cold boot to the next kernel,
and print it at boot time.
Bugs that only reproduce when kexecing from specific kernel versions are
difficult to diagnose. These issues occur when a buggy kernel kexecs into
a new kernel, with the bug manifesting only in the second kernel.
Recent examples include:
* eb2266312507 ("x86/boot: Fix page table access in 5-level to 4-level paging transition")
* 77d48d39e991 ("efistub/tpm: Use ACPI reclaim memory for event log to avoid corruption")
* 64b45dd46e15 ("x86/efi: skip memattr table on kexec boot")
As kexec-based reboots become more common, these version-dependent bugs
are appearing more frequently. At scale, correlating crashes to the
previous kernel version is challenging, especially when issues only occur
in specific transition scenarios.
Some bugs manifest only after multiple consecutive kexec reboots.
Tracking the kexec count helps identify these cases (this metric is
already used by live update sub-system).
KHO provides a reliable mechanism to pass information between kernels. By
carrying the previous kernel's release string and kexec count forward, we
can print this context at boot time to aid debugging.
The goal of this feature is to have this information being printed in
early boot, so, users can trace back kernel releases in kexec. Systemd is
not helpful because we cannot assume that the previous kernel has systemd
or even write access to the disk (common when using Linux as bootloaders)
This patch (of 6):
kho_add_subtree() assumes the fdt argument is always an FDT and calls
fdt_totalsize() on it in the debugfs code path. This assumption will
break if a caller passes arbitrary data instead of an FDT.
When CONFIG_KEXEC_HANDOVER_DEBUGFS is enabled, kho_debugfs_fdt_add() calls
__kho_debugfs_fdt_add(), which executes:
f->wrapper.size = fdt_totalsize(fdt);
Fix this by adding an explicit size parameter to kho_add_subtree() so
callers specify the blob size. This allows subtrees to contain arbitrary
data formats, not just FDTs. Update all callers:
- memblock.c: use fdt_totalsize(fdt)
- luo_core.c: use fdt_totalsize(fdt_out)
- test_kho.c: use fdt_totalsize()
- kexec_handover.c (root fdt): use fdt_totalsize(kho_out.fdt)
Also update __kho_debugfs_fdt_add() to receive the size explicitly instead
of computing it internally via fdt_totalsize(). In kho_in_debugfs_init(),
pass fdt_totalsize() for the root FDT and sub-blobs since all current
users are FDTs. A subsequent patch will persist the size in the KHO FDT
so the incoming side can handle non-FDT blobs correctly.
Link: https://lore.kernel.org/20260323110747.193569-1-duanchenghao@kylinos.cn Link: https://lore.kernel.org/20260316-kho-v9-1-ed6dcd951988@debian.org Signed-off-by: Breno Leitao <leitao@debian.org> Suggested-by: Pratyush Yadav <pratyush@kernel.org> Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Reviewed-by: Pratyush Yadav <pratyush@kernel.org> Cc: Alexander Graf <graf@amazon.com> Cc: David Hildenbrand <david@kernel.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: SeongJae Park <sj@kernel.org> Cc: Shuah Khan <skhan@linuxfoundation.org> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Vlastimil Babka <vbabka@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add a Kconfig option to default kmemleak verbose mode on at build time.
This option depends on DEBUG_KMEMLEAK_AUTO_SCAN since verbose reporting is
only meaningful when the automatic scanning thread is running.
When enabled, kmemleak prints full details (backtrace, hex dump, address)
of unreferenced objects to dmesg as they are detected during scanning,
removing the need to manually read /sys/kernel/debug/kmemleak.
Making this a compile-time option rather than a boot parameter allows
debug kernel flavors to enable verbose kmemleak reporting by default
without requiring changes to boot arguments. A machine can simply swap to
a debug kernel and benefit from kmemleak reporting automatically.
By surfacing leak reports directly in dmesg, they are automatically
forwarded through any kernel logging infrastructure and can be easily
captured by log aggregation tooling, making it practical to monitor memory
leaks across large fleets.
The verbose setting can still be toggled at runtime via
/sys/module/kmemleak/parameters/verbose.
Link: https://lore.kernel.org/20260323-kmemleak_report-v1-1-ba2cdd9c11b9@debian.org Signed-off-by: Breno Leitao <leitao@debian.org> Acked-by: SeongJae Park <sj@kernel.org> Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org> Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Cc: David Hildenbrand <david@kernel.org> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
MAINTAINERS: update MGLRU entry to reflect current status
We are moving to a far more proactive model of maintainership within mm
and thus put a great deal of emphasis on sub-maintainers being active
within the community both in terms of code contributions and review.
The MGLRU has not had much activity since being added to the kernel and
the current maintainers who kindly stepped up have unfortunately not been
able to contribute a great deal to it for over a year, nor engage all that
heavily in review.
As a result, and within no negative connotations implied whatsoever, it
seems appropriate to downgrade the current maintainers to reviewers.
At this time nobody is quite exercising the maintainer role in this area
of the kernel, but there is encouraging activity from a number of people
who are trusted elsewhere in the kernel, and who have contributed relevant
work or review.
Therefore add further reviewers, and at this stage - to reflect the
reality on the ground - we will not have any sub-maintainers listed at
all.
Each of the files listed are shared with other sections in MAINTAINERS, so
this doesn't reduce sub-maintainer coverage.
Link: https://lore.kernel.org/20260326185629.355476-1-ljs@kernel.org Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Acked-by: Axel Rasmussen <axelrasmussen@google.com> Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org> Acked-by: David Hildenbrand (Arm) <david@kernel.org> Acked-by: Barry Song <baohua@kernel.org> Acked-by: SeongJae Park <sj@kernel.org> Acked-by: Kairui Song <kasong@tencent.com> Acked-by: Qi Zheng <qi.zheng@linux.dev> Acked-by: Yuanchu Xie <yuanchu@google.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Wei Xu <weixugc@google.com> Cc: Kalesh Singh <kaleshsingh@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Qi Zheng [Fri, 27 Mar 2026 10:16:30 +0000 (18:16 +0800)]
mm: memcontrol: correct the nr_pages parameter type of mem_cgroup_update_lru_size()
The nr_pages parameter of mem_cgroup_update_lru_size() represents a page
count. During the reparenting of LRU folios, the value passed to it can
potentially exceed the maximum value of a 32-bit integer. It should be
declared as long instead of int to match the types used in lruvec size
accounting and to prevent possible overflow.
Update the parameter type to long to ensure correctness.
Link: https://lore.kernel.org/fd4140de44fa0a3978e4e2426731187fe8625f0b.1774604356.git.zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Reviewed-by: Harry Yoo (Oracle) <harry@kernel.org> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Koutný <mkoutny@suse.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeel.butt@linux.dev> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Wei Xu <weixugc@google.com> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Qi Zheng [Fri, 27 Mar 2026 10:16:29 +0000 (18:16 +0800)]
mm: memcontrol: change val type to long in __mod_memcg_{lruvec_}state()
The __mod_memcg_state() and __mod_memcg_lruvec_state() functions are also
used to reparent non-hierarchical stats. In this scenario, the values
passed to them are accumulated statistics that might be extremely large
and exceed the upper limit of a 32-bit integer.
Change the val parameter type from int to long in these functions and
their corresponding tracepoints (memcg_rstat_stats) to prevent potential
overflow issues.
After that, in memcg_state_val_in_pages(), if the passed val is negative,
the expression val * unit / PAGE_SIZE could be implicitly converted to a
massive positive number when compared with 1UL in the max() macro. This
leads to returning an incorrect massive positive value.
Fix this by using abs(val) to calculate the magnitude first, and then
restoring the sign of the value before returning the result.
Additionally, use mult_frac() to prevent potential overflow during the
multiplication of val and unit.
Link: https://lore.kernel.org/70a9440e49c464b4dca88bcabc6b491bd335c9f0.1774604356.git.zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reported-by: Harry Yoo (Oracle) <harry@kernel.org> Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Reviewed-by: Harry Yoo (Oracle) <harry@kernel.org> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Koutný <mkoutny@suse.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeel.butt@linux.dev> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Wei Xu <weixugc@google.com> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Qi Zheng [Fri, 27 Mar 2026 10:16:28 +0000 (18:16 +0800)]
mm: memcontrol: correct the type of stats_updates to unsigned long
Patch series "fix unexpected type conversions and potential overflows",
v3.
As Harry Yoo pointed out [1], in scenarios where massive state updates
occur (e.g., during the reparenting of LRU folios), the values passed to
memcg stat update functions can accumulate and exceed the upper limit of a
32-bit integer.
If the parameter types are not large enough (like 'int') or are handled
incorrectly, it can lead to severe truncation, potential overflow issues,
and unexpected type conversion bugs.
This series aims to address these issues by correcting the parameter types
in the relevant functions, and by fixing an implicit conversion bug in
memcg_state_val_in_pages().
This patch (of 3):
The memcg_rstat_updated() tracks updates for vmstats_percpu->state and
lruvec_stats_percpu->state. Since these state values are of type long,
change the val parameter passed to memcg_rstat_updated() to long as well.
Correspondingly, change the type of stats_updates in struct
memcg_vmstats_percpu and struct memcg_vmstats from unsigned int and
atomic_t to unsigned long and atomic_long_t respectively to prevent
potential overflow when handling large state updates during the
reparenting of LRU folios.
Link: https://lore.kernel.org/cover.1774604356.git.zhengqi.arch@bytedance.com Link: https://lore.kernel.org/a5b0b468e7b4fe5f26c50e36d5d016f16d92f98f.1774604356.git.zhengqi.arch@bytedance.com Link: https://lore.kernel.org/all/acDxaEgnqPI-Z4be@hyeyoo/ Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Reviewed-by: Harry Yoo (Oracle) <harry@kernel.org> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Michal Hocko <mhocko@kernel.org> Cc: Michal Koutný <mkoutny@suse.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeel.butt@linux.dev> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Wei Xu <weixugc@google.com> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:51 +0000 (19:52 +0800)]
mm: lru: add VM_WARN_ON_ONCE_FOLIO to lru maintenance helpers
We must ensure the folio is deleted from or added to the correct lruvec
list. So, add VM_WARN_ON_ONCE_FOLIO() to catch invalid users. The
VM_BUG_ON_PAGE() in move_pages_to_lru() can be removed as
add_page_to_lru_list() will perform the necessary check.
Link: https://lore.kernel.org/2c90fc006d9d730331a3caeef96f7e5dabe2036d.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Harry Yoo <harry.yoo@oracle.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:50 +0000 (19:52 +0800)]
mm: memcontrol: eliminate the problem of dying memory cgroup for LRU folios
Now that everything is set up, switch folio->memcg_data pointers to
objcgs, update the accessors, and execute reparenting on cgroup death.
Finally, folio->memcg_data of LRU folios and kmem folios will always point
to an object cgroup pointer. The folio->memcg_data of slab folios will
point to an vector of object cgroups.
Link: https://lore.kernel.org/80cb7af198dc6f2173fe616d1207a4c315ece141.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Harry Yoo <harry.yoo@oracle.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Qi Zheng [Thu, 5 Mar 2026 11:52:49 +0000 (19:52 +0800)]
mm: memcontrol: convert objcg to be per-memcg per-node type
Convert objcg to be per-memcg per-node type, so that when reparent LRU
folios later, we can hold the lru lock at the node level, thus avoiding
holding too many lru locks at once.
[zhengqi.arch@bytedance.com: reset pn->orig_objcg to NULL] Link: https://lore.kernel.org/20260309112939.31937-1-qi.zheng@linux.dev
[akpm@linux-foundation.org: fix comment typo, per Usama. Reflow comment to 80 cols]
[devnexen@gmail.com: fix obj_cgroup leak in mem_cgroup_css_online() error path] Link: https://lore.kernel.org/20260322193631.45457-1-devnexen@gmail.com
[devnexen@gmail.com: add newline, per Qi Zheng] Link: https://lore.kernel.org/20260323063007.7783-1-devnexen@gmail.com Link: https://lore.kernel.org/56c04b1c5d54f75ccdc12896df6c1ca35403ecc3.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Signed-off-by: David Carlier <devnexen@gmail.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Harry Yoo <harry.yoo@oracle.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Usama Arif <usama.arif@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Qi Zheng [Thu, 5 Mar 2026 11:52:48 +0000 (19:52 +0800)]
mm: memcontrol: prepare for reparenting non-hierarchical stats
To resolve the dying memcg issue, we need to reparent LRU folios of child
memcg to its parent memcg. This could cause problems for non-hierarchical
stats.
As Yosry Ahmed pointed out:
In short, if memory is charged to a dying cgroup at the time of
reparenting, when the memory gets uncharged the stats updates will occur
at the parent. This will update both hierarchical and non-hierarchical
stats of the parent, which would corrupt the parent's non-hierarchical
stats (because those counters were never incremented when the memory was
charged).
Now we have the following two types of non-hierarchical stats, and they
are only used in CONFIG_MEMCG_V1:
a. memcg->vmstats->state_local[i]
b. pn->lruvec_stats->state_local[i]
To ensure that these non-hierarchical stats work properly, we need to
reparent these non-hierarchical stats after reparenting LRU folios. To
this end, this commit makes the following preparations:
1. implement reparent_state_local() to reparent non-hierarchical stats
2. make css_killed_work_fn() to be called in rcu work, and implement
get_non_dying_memcg_start() and get_non_dying_memcg_end() to avoid race
between mod_memcg_state()/mod_memcg_lruvec_state()
and reparent_state_local()
Link: https://lore.kernel.org/e862995c45a7101a541284b6ebee5e5c32c89066.1772711148.git.zhengqi.arch@bytedance.com Co-developed-by: Yosry Ahmed <yosry@kernel.org> Signed-off-by: Yosry Ahmed <yosry@kernel.org> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Harry Yoo <harry.yoo@oracle.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Qi Zheng [Thu, 5 Mar 2026 11:52:46 +0000 (19:52 +0800)]
mm: workingset: use lruvec_lru_size() to get the number of lru pages
For cgroup v2, count_shadow_nodes() is the only place to read
non-hierarchical stats (lruvec_stats->state_local). To avoid the need to
consider cgroup v2 during subsequent non-hierarchical stats reparenting,
use lruvec_lru_size() instead of lruvec_page_state_local() to get the
number of lru pages.
For NR_SLAB_RECLAIMABLE_B and NR_SLAB_UNRECLAIMABLE_B cases, it appears
that the statistics here have already been problematic for a while since
slab pages have been reparented. So just ignore it for now.
Link: https://lore.kernel.org/b1d448c667a8fb377c3390d9aba43bdb7e4d5739.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Acked-by: Muchun Song <muchun.song@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Harry Yoo <harry.yoo@oracle.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Qi Zheng [Thu, 5 Mar 2026 11:52:44 +0000 (19:52 +0800)]
mm: vmscan: prepare for reparenting MGLRU folios
Similar to traditional LRU folios, in order to solve the dying memcg
problem, we also need to reparenting MGLRU folios to the parent memcg when
memcg offline.
However, there are the following challenges:
1. Each lruvec has between MIN_NR_GENS and MAX_NR_GENS generations, the
number of generations of the parent and child memcg may be different,
so we cannot simply transfer MGLRU folios in the child memcg to the
parent memcg as we did for traditional LRU folios.
2. The generation information is stored in folio->flags, but we cannot
traverse these folios while holding the lru lock, otherwise it may
cause softlockup.
3. In walk_update_folio(), the gen of folio and corresponding lru size
may be updated, but the folio is not immediately moved to the
corresponding lru list. Therefore, there may be folios of different
generations on an LRU list.
4. In lru_gen_del_folio(), the generation to which the folio belongs is
found based on the generation information in folio->flags, and the
corresponding LRU size will be updated. Therefore, we need to update
the lru size correctly during reparenting, otherwise the lru size may
be updated incorrectly in lru_gen_del_folio().
Finally, this patch chose a compromise method, which is to splice the lru
list in the child memcg to the lru list of the same generation in the
parent memcg during reparenting. And in order to ensure that the parent
memcg has the same generation, we need to increase the generations in the
parent memcg to the MAX_NR_GENS before reparenting.
Of course, the same generation has different meanings in the parent and
child memcg, this will cause confusion in the hot and cold information of
folios. But other than that, this method is simple enough, the lru size
is correct, and there is no need to consider some concurrency issues (such
as lru_gen_del_folio()).
To prepare for the above work, this commit implements the specific
functions, which will be used during reparenting.
[zhengqi.arch@bytedance.com: use list_splice_tail_init() to reparent child folios] Link: https://lore.kernel.org/20260324114937.28569-1-qi.zheng@linux.dev Link: https://lore.kernel.org/e75050354cdbc42221a04f7cf133292b61105548.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Suggested-by: Harry Yoo <harry.yoo@oracle.com> Suggested-by: Imran Khan <imran.f.khan@oracle.com> Acked-by: Harry Yoo <harry.yoo@oracle.com> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeel.butt@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Qi Zheng [Thu, 5 Mar 2026 11:52:43 +0000 (19:52 +0800)]
mm: vmscan: prepare for reparenting traditional LRU folios
To resolve the dying memcg issue, we need to reparent LRU folios of child
memcg to its parent memcg. For traditional LRU list, each lruvec of every
memcg comprises four LRU lists. Due to the symmetry of the LRU lists, it
is feasible to transfer the LRU lists from a memcg to its parent memcg
during the reparenting process.
This commit implements the specific function, which will be used during
the reparenting process.
Link: https://lore.kernel.org/a92d217a9fc82bd0c401210204a095caaf615b1c.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Muchun Song <muchun.song@linux.dev> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:42 +0000 (19:52 +0800)]
mm: memcontrol: prepare for reparenting LRU pages for lruvec lock
The following diagram illustrates how to ensure the safety of the folio
lruvec lock when LRU folios undergo reparenting.
In the folio_lruvec_lock(folio) function:
rcu_read_lock();
retry:
lruvec = folio_lruvec(folio);
/* There is a possibility of folio reparenting at this point. */
spin_lock(&lruvec->lru_lock);
if (unlikely(lruvec_memcg(lruvec) != folio_memcg(folio))) {
/*
* The wrong lruvec lock was acquired, and a retry is required.
* This is because the folio resides on the parent memcg lruvec
* list.
*/
spin_unlock(&lruvec->lru_lock);
goto retry;
}
/* Reaching here indicates that folio_memcg() is stable. */
In the memcg_reparent_objcgs(memcg) function:
spin_lock(&lruvec->lru_lock);
spin_lock(&lruvec_parent->lru_lock);
/* Transfer folios from the lruvec list to the parent's. */
spin_unlock(&lruvec_parent->lru_lock);
spin_unlock(&lruvec->lru_lock);
After acquiring the lruvec lock, it is necessary to verify whether the
folio has been reparented. If reparenting has occurred, the new lruvec
lock must be reacquired. During the LRU folio reparenting process, the
lruvec lock will also be acquired (this will be implemented in a
subsequent patch). Therefore, folio_memcg() remains unchanged while the
lruvec lock is held.
Given that lruvec_memcg(lruvec) is always equal to folio_memcg(folio)
after the lruvec lock is acquired, the lruvec_memcg_debug() check is
redundant. Hence, it is removed.
This patch serves as a preparation for the reparenting of LRU folios.
Link: https://lore.kernel.org/23f22cbb1419f277a3483018b32158ae2b86c666.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Harry Yoo <harry.yoo@oracle.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Qi Zheng [Thu, 5 Mar 2026 11:52:41 +0000 (19:52 +0800)]
mm: do not open-code lruvec lock
Now we have lruvec_unlock(), lruvec_unlock_irq() and
lruvec_unlock_irqrestore(), but no the paired lruvec_lock(),
lruvec_lock_irq() and lruvec_lock_irqsave().
There is currently no use case for lruvec_lock_irqsave(), so only
introduce lruvec_lock_irq(), and change all open-code places to use this
helper function. This looks cleaner and prepares for reparenting LRU
pages, preventing user from missing RCU lock calls due to open-code lruvec
lock.
Link: https://lore.kernel.org/2d0bafe7564e17ece46dfd58197af22ce57017dc.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Muchun Song <muchun.song@linux.dev> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:40 +0000 (19:52 +0800)]
mm: workingset: prevent lruvec release in workingset_activation()
In the near future, a folio will no longer pin its corresponding memory
cgroup. So an lruvec returned by folio_lruvec() could be released without
the rcu read lock or a reference to its memory cgroup.
In the current patch, the rcu read lock is employed to safeguard against
the release of the lruvec in workingset_activation().
This serves as a preparatory measure for the reparenting of the LRU pages.
Link: https://lore.kernel.org/c6130476affbba0a7d309a887c3df11e0167990b.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:39 +0000 (19:52 +0800)]
mm: swap: prevent lruvec release in lru_gen_clear_refs()
In the near future, a folio will no longer pin its corresponding memory
cgroup. So an lruvec returned by folio_lruvec() could be released without
the rcu read lock or a reference to its memory cgroup.
In the current patch, the rcu read lock is employed to safeguard against
the release of the lruvec in lru_gen_clear_refs().
This serves as a preparatory measure for the reparenting of the LRU pages.
Link: https://lore.kernel.org/986cd26227191a48a7c34a2a15812d361f4ebd53.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:38 +0000 (19:52 +0800)]
mm: zswap: prevent lruvec release in zswap_folio_swapin()
In the near future, a folio will no longer pin its corresponding memory
cgroup. So an lruvec returned by folio_lruvec() could be released without
the rcu read lock or a reference to its memory cgroup.
In the current patch, the rcu read lock is employed to safeguard against
the release of the lruvec in zswap_folio_swapin().
This serves as a preparatory measure for the reparenting of the LRU pages.
Link: https://lore.kernel.org/02b3f76ee8d1132f69ac5baaedce38fb82b09a48.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Nhat Pham <nphamcs@gmail.com> Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:37 +0000 (19:52 +0800)]
mm: workingset: prevent lruvec release in workingset_refault()
In the near future, a folio will no longer pin its corresponding memory
cgroup. So an lruvec returned by folio_lruvec() could be released without
the rcu read lock or a reference to its memory cgroup.
In the current patch, the rcu read lock is employed to safeguard against
the release of the lruvec in workingset_refault().
This serves as a preparatory measure for the reparenting of the LRU pages.
Link: https://lore.kernel.org/e3a8c19a9b18422b43213f6c89c451c5b6ca1577.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Yosry Ahmed <yosry@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Qi Zheng [Thu, 5 Mar 2026 11:52:36 +0000 (19:52 +0800)]
mm: zswap: prevent memory cgroup release in zswap_compress()
In the near future, a folio will no longer pin its corresponding memory
cgroup. To ensure safety, it will only be appropriate to hold the rcu
read lock or acquire a reference to the memory cgroup returned by
folio_memcg(), thereby preventing it from being released.
In the current patch, the rcu read lock is employed to safeguard against
the release of the memory cgroup in zswap_compress().
Link: https://lore.kernel.org/340f315050fb8a67caaf01b4836d4f38a41cf1a8.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Acked-by: Muchun Song <muchun.song@linux.dev> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Qi Zheng [Thu, 5 Mar 2026 11:52:35 +0000 (19:52 +0800)]
mm: thp: prevent memory cgroup release in folio_split_queue_lock{_irqsave}()
In the near future, a folio will no longer pin its corresponding memory
cgroup. To ensure safety, it will only be appropriate to hold the rcu
read lock or acquire a reference to the memory cgroup returned by
folio_memcg(), thereby preventing it from being released.
In the current patch, the rcu read lock is employed to safeguard against
the release of the memory cgroup in folio_split_queue_lock{_irqsave}().
Link: https://lore.kernel.org/ca2957c0df1126b2c71b40c738018fd5255525a6.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Acked-by: David Hildenbrand (Red Hat) <david@kernel.org> Acked-by: Muchun Song <muchun.song@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:34 +0000 (19:52 +0800)]
mm: workingset: prevent memory cgroup release in lru_gen_eviction()
In the near future, a folio will no longer pin its corresponding memory
cgroup. To ensure safety, it will only be appropriate to hold the rcu
read lock or acquire a reference to the memory cgroup returned by
folio_memcg(), thereby preventing it from being released.
In the current patch, the rcu read lock is employed to safeguard against
the release of the memory cgroup in lru_gen_eviction().
This serves as a preparatory measure for the reparenting of the LRU pages.
Link: https://lore.kernel.org/f37e8ae2d84ddc690813d834cd75735d52d1bc78.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:33 +0000 (19:52 +0800)]
mm: memcontrol: prevent memory cgroup release in mem_cgroup_swap_full()
In the near future, a folio will no longer pin its corresponding memory
cgroup. To ensure safety, it will only be appropriate to hold the rcu
read lock or acquire a reference to the memory cgroup returned by
folio_memcg(), thereby preventing it from being released.
In the current patch, the rcu read lock is employed to safeguard against
the release of the memory cgroup in mem_cgroup_swap_full().
This serves as a preparatory measure for the reparenting of the LRU pages.
Link: https://lore.kernel.org/21d1abab7342615745ea4c18a88237335ab44d13.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:32 +0000 (19:52 +0800)]
mm: mglru: prevent memory cgroup release in mglru
In the near future, a folio will no longer pin its corresponding memory
cgroup. To ensure safety, it will only be appropriate to hold the rcu
read lock or acquire a reference to the memory cgroup returned by
folio_memcg(), thereby preventing it from being released.
In the current patch, the rcu read lock is employed to safeguard against
the release of the memory cgroup in mglru.
This serves as a preparatory measure for the reparenting of the LRU pages.
Link: https://lore.kernel.org/9d887662a9d39c425742dd8468e3123316bccfe3.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:31 +0000 (19:52 +0800)]
mm: migrate: prevent memory cgroup release in folio_migrate_mapping()
In the near future, a folio will no longer pin its corresponding memory
cgroup. To ensure safety, it will only be appropriate to hold the rcu
read lock or acquire a reference to the memory cgroup returned by
folio_memcg(), thereby preventing it from being released.
In __folio_migrate_mapping(), the rcu read lock is employed to safeguard
against the release of the memory cgroup in folio_migrate_mapping().
This serves as a preparatory measure for the reparenting of the LRU pages.
Link: https://lore.kernel.org/0f156c2f1188f256855617953f8305f43e066065.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:30 +0000 (19:52 +0800)]
mm: page_io: prevent memory cgroup release in page_io module
In the near future, a folio will no longer pin its corresponding memory
cgroup. To ensure safety, it will only be appropriate to hold the rcu
read lock or acquire a reference to the memory cgroup returned by
folio_memcg(), thereby preventing it from being released.
In the current patch, the rcu read lock is employed to safeguard against
the release of the memory cgroup in swap_writeout() and
bio_associate_blkg_from_page().
This serves as a preparatory measure for the reparenting of the LRU pages.
Link: https://lore.kernel.org/7c3708358412fb02c482d0985feb5e9513a863ef.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:29 +0000 (19:52 +0800)]
mm: memcontrol: prevent memory cgroup release in count_memcg_folio_events()
In the near future, a folio will no longer pin its corresponding memory
cgroup. To ensure safety, it will only be appropriate to hold the rcu
read lock or acquire a reference to the memory cgroup returned by
folio_memcg(), thereby preventing it from being released.
In the current patch, the rcu read lock is employed to safeguard against
the release of the memory cgroup in count_memcg_folio_events().
This serves as a preparatory measure for the reparenting of the
LRU pages.
Link: https://lore.kernel.org/dea6aa0389367f7fd6b715c8837a2cf7506bd889.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:28 +0000 (19:52 +0800)]
writeback: prevent memory cgroup release in writeback module
In the near future, a folio will no longer pin its corresponding memory
cgroup. To ensure safety, it will only be appropriate to hold the rcu
read lock or acquire a reference to the memory cgroup returned by
folio_memcg(), thereby preventing it from being released.
In the current patch, the function get_mem_cgroup_css_from_folio() and the
rcu read lock are employed to safeguard against the release of the memory
cgroup.
This serves as a preparatory measure for the reparenting of the
LRU pages.
Link: https://lore.kernel.org/645f99bc344575417f67def3744f975596df2793.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:27 +0000 (19:52 +0800)]
buffer: prevent memory cgroup release in folio_alloc_buffers()
In the near future, a folio will no longer pin its corresponding memory
cgroup. To ensure safety, it will only be appropriate to hold the rcu
read lock or acquire a reference to the memory cgroup returned by
folio_memcg(), thereby preventing it from being released.
In the current patch, the function get_mem_cgroup_from_folio() is employed
to safeguard against the release of the memory cgroup. This serves as a
preparatory measure for the reparenting of the LRU pages.
Link: https://lore.kernel.org/d6d48fdcf329c549373ac0a1c80fd9f38067e34e.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:26 +0000 (19:52 +0800)]
mm: memcontrol: prevent memory cgroup release in get_mem_cgroup_from_folio()
In the near future, a folio will no longer pin its corresponding memory
cgroup. To ensure safety, it will only be appropriate to hold the rcu
read lock or acquire a reference to the memory cgroup returned by
folio_memcg(), thereby preventing it from being released.
In the current patch, the rcu read lock is employed to safeguard against
the release of the memory cgroup in get_mem_cgroup_from_folio().
This serves as a preparatory measure for the reparenting of the
LRU pages.
Link: https://lore.kernel.org/a5a64c6173a566bd21534606aeaaa9220cb1366d.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:25 +0000 (19:52 +0800)]
mm: memcontrol: return root object cgroup for root memory cgroup
Memory cgroup functions such as get_mem_cgroup_from_folio() and
get_mem_cgroup_from_mm() return a valid memory cgroup pointer, even for
the root memory cgroup. In contrast, the situation for object cgroups has
been different.
Previously, the root object cgroup couldn't be returned because it didn't
exist. Now that a valid root object cgroup exists, for the sake of
consistency, it's necessary to align the behavior of object-cgroup-related
operations with that of memory cgroup APIs.
Link: https://lore.kernel.org/e9c3f40ba7681d9753372d4ee2ac7a0216848b95.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:24 +0000 (19:52 +0800)]
mm: memcontrol: allocate object cgroup for non-kmem case
To allow LRU page reparenting, the objcg infrastructure is no longer
solely applicable to the kmem case. In this patch, we extend the scope of
the objcg infrastructure beyond the kmem case, enabling LRU folios to
reuse it for folio charging purposes.
It should be noted that LRU folios are not accounted for at the root
level, yet the folio->memcg_data points to the root_mem_cgroup. Hence,
the folio->memcg_data of LRU folios always points to a valid pointer.
However, the root_mem_cgroup does not possess an object cgroup.
Therefore, we also allocate an object cgroup for the root_mem_cgroup.
Link: https://lore.kernel.org/b77274aa8e3f37c419bedf4782943fd5885dda82.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Reviewed-by: Chen Ridong <chenridong@huawei.com> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:23 +0000 (19:52 +0800)]
mm: vmscan: refactor move_folios_to_lru()
In a subsequent patch, we'll reparent the LRU folios. The folios that are
moved to the appropriate LRU list can undergo reparenting during the
move_folios_to_lru() process. Hence, it's incorrect for the caller to
hold a lruvec lock. Instead, we should utilize the more general interface
of folio_lruvec_relock_irq() to obtain the correct lruvec lock.
This patch involves only code refactoring and doesn't introduce any
functional changes.
Link: https://lore.kernel.org/6f1dac88b61e2e3cb7a3e90bacdf06b654acfc15.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Chen Ridong <chenridong@huawei.com> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Qi Zheng [Thu, 5 Mar 2026 11:52:22 +0000 (19:52 +0800)]
mm: vmscan: prepare for the refactoring the move_folios_to_lru()
Once we refactor move_folios_to_lru(), its callers will no longer have to
hold the lruvec lock; For shrink_inactive_list(), shrink_active_list() and
evict_folios(), IRQ disabling is only needed for __count_vm_events() and
__mod_node_page_state().
To avoid using local_irq_disable() on the PREEMPT_RT kernel, let's make
all callers of move_folios_to_lru() use IRQ-safed count_vm_events() and
mod_node_page_state().
Link: https://lore.kernel.org/b3a202f1787b0857bb6cbe059fffb8edefaf67b7.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Reviewed-by: Chen Ridong <chenridong@huawei.com> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Acked-by: Muchun Song <muchun.song@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:21 +0000 (19:52 +0800)]
mm: rename unlock_page_lruvec_irq and its variants
It is inappropriate to use folio_lruvec_lock() variants in conjunction
with unlock_page_lruvec() variants, as this involves the inconsistent
operation of locking a folio while unlocking a page. To rectify this, the
functions unlock_page_lruvec{_irq, _irqrestore} are renamed to
lruvec_unlock{_irq,_irqrestore}.
Link: https://lore.kernel.org/4e5e05271a250df4d1812e1832be65636a78c957.1772711148.git.zhengqi.arch@bytedance.com Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Reviewed-by: Chen Ridong <chenridong@huawei.com> Acked-by: David Hildenbrand (Red Hat) <david@kernel.org> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Muchun Song [Thu, 5 Mar 2026 11:52:19 +0000 (19:52 +0800)]
mm: memcontrol: remove dead code of checking parent memory cgroup
Patch series "Eliminate Dying Memory Cgroup", v6.
Introduction
============
This patchset is intended to transfer the LRU pages to the object cgroup
without holding a reference to the original memory cgroup in order to
address the issue of the dying memory cgroup. A consensus has already
been reached regarding this approach recently [1].
Background
==========
The issue of a dying memory cgroup refers to a situation where a memory
cgroup is no longer being used by users, but memory (the metadata
associated with memory cgroups) remains allocated to it. This situation
may potentially result in memory leaks or inefficiencies in memory
reclamation and has persisted as an issue for several years. Any memory
allocation that endures longer than the lifespan (from the users'
perspective) of a memory cgroup can lead to the issue of dying memory
cgroup. We have exerted greater efforts to tackle this problem by
introducing the infrastructure of object cgroup [2].
Presently, numerous types of objects (slab objects, non-slab kernel
allocations, per-CPU objects) are charged to the object cgroup without
holding a reference to the original memory cgroup. The final allocations
for LRU pages (anonymous pages and file pages) are charged at allocation
time and continues to hold a reference to the original memory cgroup until
reclaimed.
File pages are more complex than anonymous pages as they can be shared
among different memory cgroups and may persist beyond the lifespan of the
memory cgroup. The long-term pinning of file pages to memory cgroups is a
widespread issue that causes recurring problems in practical scenarios
[3]. File pages remain unreclaimed for extended periods. Additionally,
they are accessed by successive instances (second, third, fourth, etc.) of
the same job, which is restarted into a new cgroup each time. As a
result, unreclaimable dying memory cgroups accumulate, leading to memory
wastage and significantly reducing the efficiency of page reclamation.
Fundamentals
============
A folio will no longer pin its corresponding memory cgroup. It is
necessary to ensure that the memory cgroup or the lruvec associated with
the memory cgroup is not released when a user obtains a pointer to the
memory cgroup or lruvec returned by folio_memcg() or folio_lruvec().
Users are required to hold the RCU read lock or acquire a reference to the
memory cgroup associated with the folio to prevent its release if they are
not concerned about the binding stability between the folio and its
corresponding memory cgroup. However, some users of folio_lruvec() (i.e.,
the lruvec lock) desire a stable binding between the folio and its
corresponding memory cgroup. An approach is needed to ensure the
stability of the binding while the lruvec lock is held, and to detect the
situation of holding the incorrect lruvec lock when there is a race
condition during memory cgroup reparenting. The following four steps are
taken to achieve these goals.
1. The first step to be taken is to identify all users of both functions
(folio_memcg() and folio_lruvec()) who are not concerned about binding
stability and implement appropriate measures (such as holding a RCU read
lock or temporarily obtaining a reference to the memory cgroup for a
brief period) to prevent the release of the memory cgroup.
2. Secondly, the following refactoring of folio_lruvec_lock() demonstrates
how to ensure the binding stability from the user's perspective of
folio_lruvec().
From the perspective of memory cgroup removal, the entire reparenting
process (altering the binding relationship between folio and its memory
cgroup and moving the LRU lists to its parental memory cgroup) should be
carried out under both the lruvec lock of the memory cgroup being removed
and the lruvec lock of its parent.
3. Finally, transfer the LRU pages to the object cgroup without holding a
reference to the original memory cgroup.
Effect
======
Finally, it can be observed that the quantity of dying memory cgroups will
not experience a significant increase if the following test script is
executed to reproduce the issue.
#!/bin/bash
# Create a temporary file 'temp' filled with zero bytes
dd if=/dev/zero of=temp bs=4096 count=1
# Display memory-cgroup info from /proc/cgroups
cat /proc/cgroups | grep memory
for i in {0..2000}
do
mkdir /sys/fs/cgroup/memory/test$i
echo $$ > /sys/fs/cgroup/memory/test$i/cgroup.procs
# Potentially create a dying memory cgroup
rmdir /sys/fs/cgroup/memory/test$i
done
# Display memory-cgroup info after test
cat /proc/cgroups | grep memory
rm -f temp log
This patch (of 33):
Since the no-hierarchy mode has been deprecated after the commit:
commit bef8620cd8e0 ("mm: memcg: deprecate the non-hierarchical mode").
As a result, parent_mem_cgroup() will not return NULL except when passing
the root memcg, and the root memcg cannot be offline. Hence, it's safe to
remove the check on the returned value of parent_mem_cgroup(). Remove the
corresponding dead code.
Link: https://lore.kernel.org/f4481291bf8c6561dd8949045b5a1ed4008a6b63.1772711148.git.zhengqi.arch@bytedance.com Link: https://lore.kernel.org/linux-mm/Z6OkXXYDorPrBvEQ@hm-sls2/ Link: https://lwn.net/Articles/895431/ Link: https://github.com/systemd/systemd/pull/36827 Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: Roman Gushchin <roman.gushchin@linux.dev> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Reviewed-by: Harry Yoo <harry.yoo@oracle.com> Reviewed-by: Chen Ridong <chenridong@huawei.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev> Cc: Allen Pais <apais@linux.microsoft.com> Cc: Axel Rasmussen <axelrasmussen@google.com> Cc: Baoquan He <bhe@redhat.com> Cc: Chengming Zhou <chengming.zhou@linux.dev> Cc: David Hildenbrand <david@kernel.org> Cc: Hamza Mahfooz <hamzamahfooz@linux.microsoft.com> Cc: Hugh Dickins <hughd@google.com> Cc: Imran Khan <imran.f.khan@oracle.com> Cc: Kamalesh Babulal <kamalesh.babulal@oracle.com> Cc: Lance Yang <lance.yang@linux.dev> Cc: Liam Howlett <Liam.Howlett@oracle.com> Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org> Cc: Michal Hocko <mhocko@suse.com> Cc: Michal Koutný <mkoutny@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Nhat Pham <nphamcs@gmail.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Usama Arif <usamaarif642@gmail.com> Cc: Vlastimil Babka <vbabka@kernel.org> Cc: Wei Xu <weixugc@google.com> Cc: Yosry Ahmed <yosry@kernel.org> Cc: Yuanchu Xie <yuanchu@google.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Lorenzo Stoakes [Mon, 13 Apr 2026 10:57:13 +0000 (11:57 +0100)]
mm/vma: remove __vma_check_mmap_hook()
Commit c50ca15dd496 ("mm: add vm_ops->mapped hook") introduced
__vma_check_mmap_hook() in order to assert that a driver doesn't
incorrectly implement both an f_op->mmap() and a vm_ops->mapped hook, the
latter of which would not ultimately get invoked.
However, this did not correctly account for stacked drivers (or drivers
that otherwise use the compatibility layer) which might recursively call
an mmap_prepare hook via the compatibility layer.
Thus the nested mmap_prepare() invocation might result in a VMA which has
vm_ops->mapped set with an overlaying mmap() hook, causing the
__vma_check_mmap_hook() to fail in vfs_mmap(), wrongly failing the
operation.
This patch resolves this by simply removing the check, as we can't be
certain that an mmap() hook doesn't at some point invoke the compatibility
layer, and it's not worth trying to track it.
Link: https://lore.kernel.org/20260413105713.92625-1-ljs@kernel.org Fixes: c50ca15dd496 ("mm: add vm_ops->mapped hook") Reported-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com> Closes: https://lore.kernel.org/all/adx2ws5z0NMIe5Yj@shinmob/ Signed-off-by: Lorenzo Stoakes <ljs@kernel.org> Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org> Tested-by: Shinichiro Kawasaki <shinichiro.kawasaki@wdc.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christian Brauner <brauner@kernel.org> Cc: David Hildenbrand <david@kernel.org> Cc: Jan Kara <jack@suse.cz> Cc: Liam Howlett <liam.howlett@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Mike Rapoport <rppt@kernel.org> Cc: Suren Baghdasaryan <surenb@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Dan Carpenter [Fri, 10 Apr 2026 15:24:49 +0000 (00:24 +0900)]
ntfs: fix potential 32-bit truncation in ntfs_write_cb()
Smatch warned that the bitwise negation in ntfs_write_cb() might lead to
unintended truncation. Casting the block size to loff_t before bitwise
negation prevents the upper 32 bits of pos from being incorrectly zeroed
out during the calculation of new_vcn.
Signed-off-by: Dan Carpenter <error27@gmail.com> Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com> Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
ntfs: fix uninitialized variable in ntfs_map_runlist_nolock
Smatch reported that ctx_needs_reset could be used uninitialized if
ntfs_map_runlist_nolock() fails early when a search context is provided.
Specifically, if the function returns -EIO because the attribute is
resident, the code jumps to err_out. This initializes ctx_needs_reset to
false to satisfy the static checker.
Reported-by: Dan Carpenter <error27@gmail.com> Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com> Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
ntfs: fix uninitialized variables in ntfs_ea_set_wsl_inode()
Smatch reported uninitialized symbol warnings in ntfs_ea_set_wsl_inode()
and __ntfs_create(). In ntfs_ea_set_wsl_inode(), the err variable could be
returned without initialization if no flags are set and rdev is zero.
Additionally, ea_size might remain uninitialized from the caller's
perspective if no EA operations are performed. While these cases might not
be triggered under current logic, we initialize them to zero to satisfy
the static checker.
Reported-by: Dan Carpenter <error27@gmail.com> Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com> Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
ntfs: fix uninitialized pointer in ntfs_write_mft_block
Smatch reported that the variable rl could be used uninitialized in
ntfs_write_mft_block(). After analyzing the code,
when vol->cluster_size == NTFS_BLOCK_SIZE (512), it is smaller than
folio_size, so rl is guaranteed to be initialized. If vol->cluster_size
is larger, the condition to access rl becomes false, so a runtime error is
not expected to occur. However, to make the static checker happy,
this patch initializes rl to NULL and adds an explicit check before
its usage.
Reported-by: Dan Carpenter <error27@gmail.com> Reviewed-by: Hyunchul Lee <hyc.lee@gmail.com> Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Hyunchul Lee [Wed, 1 Apr 2026 07:24:57 +0000 (16:24 +0900)]
ntfs: zero out stale data in straddle block beyond initialized_size
ntfs_read_iomap_begin_non_resident() rounds up MAPPED extents
to the block boundary of initialized_size. This ensures that
any subsequent blocks are treated as IOMAP_UNWRITTEN, but
it also causes the "straddle block" containing initialized_size
to be read from disk. The disk data beyond initialized_size in
this block is stale and must be zeroed to prevent data leakage.
Signed-off-by: Hyunchul Lee <hyc.lee@gmail.com> Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Merge tag 'mtd/for-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux
Pull MTD updates from Miquel Raynal:
"MTD changes:
- mtdconcat finally makes it in, after several years of being merged
and reverted
- Baikal SoC support is being removed, so MTD bits are being removed
as well
- misc cleanups
NAND changes:
- SunXi driver support for new versions of the Allwinner NAND
controller.
- DT-binding improvements and cleanups.
- A few fixes (Realtek ECC and Winbond SPI NAND), aside with the
usual load of misc changes.
SPI NOR fixes:
- Enable die erase on MT35XU02GCBA. We knew this flash needed this
fixup since 7f77c561e227 ("mtd: spi-nor: micron-st: add TODO for
fixing mt35xu02gcba") but did not add it due to lack of hardware to
test on.
- Fix locking on some Winbond w25q series flashes.
- Fix Auto Address Increment (AAI) writes on SST that flashes that
start on odd address. The write enable latch needs to be set again
after the single byte program"
* tag 'mtd/for-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/mtd/linux: (44 commits)
mtd: spinand: winbond: Declare the QE bit on W25NxxJW
mtd: spi-nor: micron-st: Enable die erase support for MT35XU02GCBA
mtd: spi-nor: winbond: Fix locking support for w25q256jw
mtd: spi-nor: sst: Fix write enable before AAI sequence
mtd: spi-nor: winbond: Fix locking support for w25q64jvm
mtd: spi-nor: winbond: Fix locking support for w25q256jwm
dt-bindings: mtd: mxc-nand: add missing compatible string and ref to nand-controller-legacy.yaml
dt-bindings: mtd: gpmi-nand: ref to nand-controller-legacy.yaml
dt-bindings: mtd: refactor NAND bindings and add nand-controller-legacy.yaml
mtd: spinand: winbond: Clarify when to enable the HS bit
mtd: rawnand: sunxi: introduce maximize variable user data length
mtd: rawnand: sunxi: fix typos in comments
mtd: rawnand: sunxi: change error prone variable name
mtd: rawnand: sunxi: remove dead code
mtd: rawnand: sunxi: make the code more self-explanatory
mtd: rawnand: sunxi: replace hard coded value by a define - take2
mtd: rawnand: sunxi: do not count BBM bytes twice
mtd: rawnand: sunxi: fix sunxi_nfc_hw_ecc_read_extra_oob
mtd: rawnand: sunxi: sunxi_nand_ooblayout_free code clarification
mtd: cmdlinepart: use a flexible array member
...
Merge tag 'ext4_for_linux-7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4
Pull ext4 updates from Ted Ts'o:
- Refactor code paths involved with partial block zero-out in
prearation for converting ext4 to use iomap for buffered writes
- Remove use of d_alloc() from ext4 in preparation for the deprecation
of this interface
- Replace some J_ASSERTS with a journal abort so we can avoid a kernel
panic for a localized file system error
- Simplify various code paths in mballoc, move_extent, and fast commit
- Fix rare deadlock in jbd2_journal_cancel_revoke() that can be
triggered by generic/013 when blocksize < pagesize
- Fix memory leak when releasing an extended attribute when its value
is stored in an ea_inode
- Fix various potential kunit test bugs in fs/ext4/extents.c
- Fix potential out-of-bounds access in check_xattr() with a corrupted
file system
- Make the jbd2_inode dirty range tracking safe for lockless reads
- Avoid a WARN_ON when writeback files due to a corrupted file system;
we already print an ext4 warning indicatign that data will be lost,
so the WARN_ON is not necessary and doesn't add any new information
* tag 'ext4_for_linux-7.0-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (37 commits)
jbd2: fix deadlock in jbd2_journal_cancel_revoke()
ext4: fix missing brelse() in ext4_xattr_inode_dec_ref_all()
ext4: fix possible null-ptr-deref in mbt_kunit_exit()
ext4: fix possible null-ptr-deref in extents_kunit_exit()
ext4: fix the error handling process in extents_kunit_init).
ext4: call deactivate_super() in extents_kunit_exit()
ext4: fix miss unlock 'sb->s_umount' in extents_kunit_init()
ext4: fix bounds check in check_xattrs() to prevent out-of-bounds access
ext4: zero post-EOF partial block before appending write
ext4: move pagecache_isize_extended() out of active handle
ext4: remove ctime/mtime update from ext4_alloc_file_blocks()
ext4: unify SYNC mode checks in fallocate paths
ext4: ensure zeroed partial blocks are persisted in SYNC mode
ext4: move zero partial block range functions out of active handle
ext4: pass allocate range as loff_t to ext4_alloc_file_blocks()
ext4: remove handle parameters from zero partial block functions
ext4: move ordered data handling out of ext4_block_do_zero_range()
ext4: rename ext4_block_zero_page_range() to ext4_block_zero_range()
ext4: factor out journalled block zeroing range
ext4: rename and extend ext4_block_truncate_page()
...
Merge tag 'for-linus-7.1-ofs1' of git://git.kernel.org/pub/scm/linux/kernel/git/hubcap/linux
Pull orangefs updates from Mike Marshall:
"Fixes:
- validate getxattr response length
- don't overflow the bufmap slot on readahead
- fix parsing problem with kernel debug keywords
Cleanup:
- take better advantage of strscpy
New:
- manage bufmap as folios
- add usercopy whitelist to orangefs_op_cache"
* tag 'for-linus-7.1-ofs1' of git://git.kernel.org/pub/scm/linux/kernel/git/hubcap/linux:
bufmap: manage as folios, V2.
orangefs: validate getxattr response length
orangefs_readahead: don't overflow the bufmap slot.
debugfs: take better advantage of strscpy.
orangefs: add usercopy whitelist to orangefs_op_cache
orangefs-debugfs.c: fix parsing problem with kernel debug keywords.
Merge tag 'ntfs-for-7.1-rc1-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/linkinjeon/ntfs
Pull ntfs resurrection from Namjae Jeon:
"Ever since Kari Argillander’s 2022 report [1] regarding the state of
the ntfs3 driver, I have spent the last 4 years working to provide
full write support and current trends (iomap, no buffer head, folio),
enhanced performance, stable maintenance, utility support including
fsck for NTFS in Linux.
This new implementation is built upon the clean foundation of the
original read-only NTFS driver, adding:
- Write support:
Implemented full write support based on the classic read-only NTFS
driver. Added delayed allocation to improve write performance
through multi-cluster allocation and reduced fragmentation of the
cluster bitmap.
- iomap conversion:
Switched buffered IO (reads/writes), direct IO, file extent
mapping, readpages, and writepages to use iomap.
- Remove buffer_head:
Completely removed buffer_head usage by converting to folios. As a
result, the dependency on CONFIG_BUFFER_HEAD has been removed from
Kconfig.
- Stability improvements:
The new ntfs driver passes 326 xfstests, compared to 273 for ntfs3.
All tests passed by ntfs3 are a complete subset of the tests passed
by this implementation. Added support for fallocate, idmapped
mounts, permissions, and more.
Merge tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf
Pull bpf fixes from Alexei Starovoitov:
"Most of the diff stat comes from Xu Kuohai's fix to emit ENDBR/BTI,
since all JITs had to be touched to move constant blinding out and
pass bpf_verifier_env in.
- Fix use-after-free in arena_vm_close on fork (Alexei Starovoitov)
- Dissociate struct_ops program with map if map_update fails (Amery
Hung)
- Fix out-of-range and off-by-one bugs in arm64 JIT (Daniel Borkmann)
- Fix precedence bug in convert_bpf_ld_abs alignment check (Daniel
Borkmann)
- Fix arg tracking for imprecise/multi-offset in BPF_ST/STX insns
(Eduard Zingerman)
- Copy token from main to subprogs to fix missing kallsyms (Eduard
Zingerman)
- Prevent double close and leak of btf objects in libbpf (Jiri Olsa)
- Fix af_unix null-ptr-deref in sockmap (Michal Luczaj)
- Fix NULL deref in map_kptr_match_type for scalar regs (Mykyta
Yatsenko)
- Avoid unnecessary IPIs. Remove redundant bpf_flush_icache() in
arm64 and riscv JITs (Puranjay Mohan)
- Fix out of bounds access. Validate node_id in arena_alloc_pages()
(Puranjay Mohan)
- Reject BPF-to-BPF calls and callbacks in arm32 JIT (Puranjay Mohan)
- Refactor all JITs to pass bpf_verifier_env to emit ENDBR/BTI for
indirect jump targets on x86-64, arm64 JITs (Xu Kuohai)
- Allow UTF-8 literals in bpf_bprintf_prepare() (Yihan Ding)"
* tag 'bpf-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf: (32 commits)
bpf, arm32: Reject BPF-to-BPF calls and callbacks in the JIT
bpf: Dissociate struct_ops program with map if map_update fails
bpf: Validate node_id in arena_alloc_pages()
libbpf: Prevent double close and leak of btf objects
selftests/bpf: cover UTF-8 trace_printk output
bpf: allow UTF-8 literals in bpf_bprintf_prepare()
selftests/bpf: Reject scalar store into kptr slot
bpf: Fix NULL deref in map_kptr_match_type for scalar regs
bpf: Fix precedence bug in convert_bpf_ld_abs alignment check
bpf, arm64: Emit BTI for indirect jump target
bpf, x86: Emit ENDBR for indirect jump targets
bpf: Add helper to detect indirect jump targets
bpf: Pass bpf_verifier_env to JIT
bpf: Move constants blinding out of arch-specific JITs
bpf, sockmap: Take state lock for af_unix iter
bpf, sockmap: Fix af_unix null-ptr-deref in proto update
selftests/bpf: Extend bpf_iter_unix to attempt deadlocking
bpf, sockmap: Fix af_unix iter deadlock
bpf, sockmap: Annotate af_unix sock:: Sk_state data-races
selftests/bpf: verify kallsyms entries for token-loaded subprograms
...
Merge tag 'cxl-for-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl
Pull CXL (Compute Express Link) updates from Dave Jiang:
"The significant change of interest is the handling of soft reserved
memory conflict between CXL and HMEM. In essence CXL will be the first
to claim the soft reserved memory ranges that belongs to CXL and
attempt to enumerate them with best effort. If CXL is not able to
enumerate the ranges it will punt them to HMEM.
There are also MAINTAINERS email changes from Dan Williams and
Jonathan Cameron"
* tag 'cxl-for-7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl: (37 commits)
MAINTAINERS: Update Jonathan Cameron's email address
cxl/hdm: Add support for 32 switch decoders
MAINTAINERS: Update address for Dan Williams
tools/testing/cxl: Enable replay of user regions as auto regions
cxl/region: Add a region sysfs interface for region lock status
tools/testing/cxl: Test dax_hmem takeover of CXL regions
tools/testing/cxl: Simulate auto-assembly failure
dax/hmem: Parent dax_hmem devices
dax/hmem: Fix singleton confusion between dax_hmem_work and hmem devices
dax/hmem: Reduce visibility of dax_cxl coordination symbols
cxl/region: Constify cxl_region_resource_contains()
cxl/region: Limit visibility of cxl_region_contains_resource()
dax/cxl: Fix HMEM dependencies
cxl/region: Fix use-after-free from auto assembly failure
cxl/core: Check existence of cxl_memdev_state in poison test
cxl/core: use cleanup.h for devm_cxl_add_dax_region
cxl/core/region: move dax region device logic into region_dax.c
cxl/core/region: move pmem region driver logic into region_pmem.c
dax/hmem, cxl: Defer and resolve Soft Reserved ownership
cxl/region: Add helper to check Soft Reserved containment by CXL regions
...
Merge tag 'stop-machine.2026.04.16a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu
Pull stop-machine update from Paul McKenney:
- kernel-doc updates for stop_machine() and stop_machine_cpuslocked()
functions
* tag 'stop-machine.2026.04.16a' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu:
stop_machine: Fix the documentation for a NULL cpus argument
Merge tag 'integrity-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity
Pull integrity updates from Mimi Zohar:
"There are two main changes, one feature removal, some code cleanup,
and a number of bug fixes.
Main changes:
- Detecting secure boot mode was limited to IMA. Make detecting
secure boot mode accessible to EVM and other LSMs
- IMA sigv3 support was limited to fsverity. Add IMA sigv3 support
for IMA regular file hashes and EVM portable signatures
Remove:
- Remove IMA support for asychronous hash calculation originally
added for hardware acceleration
Cleanup:
- Remove unnecessary Kconfig CONFIG_MODULE_SIG and CONFIG_KEXEC_SIG
tests
- Add descriptions of the IMA atomic flags
Bug fixes:
- Like IMA, properly limit EVM "fix" mode
- Define and call evm_fix_hmac() to update security.evm
- Fallback to using i_version to detect file change for filesystems
that do not support STATX_CHANGE_COOKIE
- Address missing kernel support for configured (new) TPM hash
algorithms
- Add missing crypto_shash_final() return value"
* tag 'integrity-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
evm: Enforce signatures version 3 with new EVM policy 'bit 3'
integrity: Allow sigv3 verification on EVM_XATTR_PORTABLE_DIGSIG
ima: add support to require IMA sigv3 signatures
ima: add regular file data hash signature version 3 support
ima: Define asymmetric_verify_v3() to verify IMA sigv3 signatures
ima: remove buggy support for asynchronous hashes
integrity: Eliminate weak definition of arch_get_secureboot()
ima: Add code comments to explain IMA iint cache atomic_flags
ima_fs: Correctly create securityfs files for unsupported hash algos
ima: check return value of crypto_shash_final() in boot aggregate
ima: Define and use a digest_size field in the ima_algo_desc structure
powerpc/ima: Drop unnecessary check for CONFIG_MODULE_SIG
ima: efi: Drop unnecessary check for CONFIG_MODULE_SIG/CONFIG_KEXEC_SIG
ima: fallback to using i_version to detect file change
evm: fix security.evm for a file with IMA signature
s390: Drop unnecessary CONFIG_IMA_SECURE_AND_OR_TRUSTED_BOOT
evm: Don't enable fix mode when secure boot is enabled
integrity: Make arch_ima_get_secureboot integrity-wide
Merge tag 'hwlock-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux
Pull hwspinlock updates from Bjorn Andersson:
"Remove the unused u8500 hardware spinlock driver, and clean out the
hwspinlock_pdata struct as this was the last user of the struct"
* tag 'hwlock-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux:
hwspinlock: remove now unused pdata from header file
hwspinlock: u8500: delete driver
Merge tag 'rpmsg-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux
Pull rpmsg updates from Bjorn Andersson:
"Mark 'data' argument in rpmsg_send() const, and perculate to related
drivers. Replace deprecated class_destroy() with class_unregister()"
* tag 'rpmsg-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux:
media: platform: mtk-mdp3: Constify buffer passed to mdp_vpu_sendmsg()
ASoC: qcom: Constify GPR packet being send over GPR interface
rpmsg: Constify buffer passed to send API
remoteproc: mtk_scp: Constify buffer passed to scp_send_ipi()
remoteproc: mtk_scp_ipi: Constify buffer passed to scp_ipi_send()
drivers: rpmsg: class_destroy() is deprecated
Merge tag 'rproc-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux
Pull remoteproc updates from Bjorn Andersson:
- Move requesting of IRQs in TI Keystone driver to probe time instead
of remoteproc start, to allow better handling of errors.
- Introduce support for more than 10 entries in the Qualcomm minidump
implementation.
- Add audio DSP remoteproc support for the Qualcomm Eliza platform. Add
modem remoteproc support for the Qualcomm MDM9607, MSM8917, MSM8937,
and MSM8940 platforms.
- Add list of Qualcomm QMI service ids to the QMI header file, in order
to avoid sprinkling them across the various drivers using them.
Migrate sysmon to use this constant.
- Fix several issues related to DeviceTree parsing and mailbox handling
in the Xilinx R5F remote processor driver.
- Fix incorrect error checks in reserved memory handling and polish the
code across i.MX and TI drivers.
* tag 'rproc-v7.1' of git://git.kernel.org/pub/scm/linux/kernel/git/remoteproc/linux: (35 commits)
remoteproc: qcom: pas: Add Eliza ADSP support
dt-bindings: remoteproc: qcom,milos-pas: Document Eliza ADSP
remoteproc: qcom: Add missing space before closing bracket
dt-bindings: remoteproc: qcom: Drop types for firmware-name
remoteproc: qcom: Fix minidump out-of-bounds access on subsystems array
dt-bindings: remoteproc: k3-r5f: Add memory-region-names
dt-bindings: remoteproc: k3-r5f: Split up memory regions
remoteproc: use SIZE_MAX in rproc_u64_fit_in_size_t()
dt-bindings: remoteproc: qcom,sm8550-pas: Add Glymur CDSP
dt-bindings: remoteproc: qcom,sm8550-pas: Add Glymur ADSP
remoteproc: xlnx: Release mailbox channels on shutdown
remoteproc: sysmon: Use the unified QMI service ID instead of defining it locally
remoteproc: xlnx: Only access buffer information if IPI is buffered
remoteproc: xlnx: Avoid mailbox setup
remoteproc: keystone: Request IRQs in probe()
remoteproc: pru: Remove empty remove callback
remoteproc: pru: Use rproc_of_parse_firmware() to get firmware name
remoteproc: da8xx: Reorder resource fetching in probe()
remoteproc: da8xx: Remove unused local struct data
remoteproc: da8xx: Use dev_err_probe()
...
Merge tag 'for-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/pateldipen1984/linux
Pull hte updates from Dipen Patel:
- Add tegra264 HTE driver and dt binding support
- Remove tegra194 SoC Kconfig dependency
- Replace use of system_unbound_wq with system_dfl_wq
* tag 'for-7.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/pateldipen1984/linux:
hte: tegra194: Add Tegra264 GTE support
dt-bindings: timestamp: Add Tegra264 support
hte: tegra194: remove Kconfig dependency on Tegra194 SoC
hte: replace use of system_unbound_wq with system_dfl_wq
Marco Crivellari [Mon, 23 Feb 2026 09:29:20 +0000 (10:29 +0100)]
block/blk-throttle: Add WQ_PERCPU to alloc_workqueue users
This continues the effort to refactor workqueue APIs, which began with
the introduction of new workqueues and a new alloc_workqueue flag in:
commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")
The refactoring is going to alter the default behavior of
alloc_workqueue() to be unbound by default.
With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND
must now use WQ_PERCPU. For more details see the Link tag below.
In order to keep alloc_workqueue() behavior identical, explicitly request
WQ_PERCPU.
Marco Crivellari [Mon, 23 Feb 2026 09:29:19 +0000 (10:29 +0100)]
block: Add WQ_PERCPU to alloc_workqueue users
This continues the effort to refactor workqueue APIs, which began with
the introduction of new workqueues and a new alloc_workqueue flag in:
commit 128ea9f6ccfb ("workqueue: Add system_percpu_wq and system_dfl_wq")
commit 930c2ea566af ("workqueue: Add new WQ_PERCPU flag")
The refactoring is going to alter the default behavior of
alloc_workqueue() to be unbound by default.
With the introduction of the WQ_PERCPU flag (equivalent to !WQ_UNBOUND),
any alloc_workqueue() caller that doesn’t explicitly specify WQ_UNBOUND
must now use WQ_PERCPU. For more details see the Link tag below.
In order to keep alloc_workqueue() behavior identical, explicitly request
WQ_PERCPU.
Naman Jain [Fri, 10 Apr 2026 15:34:14 +0000 (15:34 +0000)]
block: relax pgmap check in bio_add_page for compatible zone device pages
bio_add_page() and bio_integrity_add_page() reject pages from different
dev_pagemaps entirely, returning 0 even when those pages have compatible
DMA mapping requirements. This forces callers to start a new bio when
buffers span pgmap boundaries, even though the pages could safely coexist
as separate bvec entries.
This matters for guests where memory is registered through
devm_memremap_pages() with MEMORY_DEVICE_GENERIC in multiple calls,
creating separate dev_pagemaps for each chunk. When a direct I/O buffer
spans two such chunks, bio_add_page() rejects the second page, forcing an
unnecessary bio split or I/O failure.
Introduce zone_device_pages_compatible() in blk.h to check whether two
pages can coexist in the same bio as separate bvec entries. The block DMA
iterator (blk_dma_map_iter_start) caches the P2PDMA mapping state from the
first segment and applies it to all others, so P2PDMA pages from different
pgmaps must not be mixed, and neither must P2PDMA and non-P2PDMA pages.
All other combinations (MEMORY_DEVICE_GENERIC pages from different pgmaps,
or MEMORY_DEVICE_GENERIC with normal RAM) use the same dma_map_phys path
and are safe.
Replace the blanket zone_device_pages_have_same_pgmap() rejection with
zone_device_pages_compatible(), while keeping
zone_device_pages_have_same_pgmap() as a merge guard.
Pages from different pgmaps can be added as separate bvec entries but
must not be coalesced into the same segment, as that would make
it impossible to recover the correct pgmap via page_pgmap().
Fixes: 49580e690755 ("block: add check when merging zone device pages") Cc: stable@vger.kernel.org Signed-off-by: Naman Jain <namjain@linux.microsoft.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Link: https://patch.msgid.link/20260410153414.4159050-3-namjain@linux.microsoft.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Naman Jain [Fri, 10 Apr 2026 15:34:13 +0000 (15:34 +0000)]
block: add pgmap check to biovec_phys_mergeable
biovec_phys_mergeable() is used by the request merge, DMA mapping,
and integrity merge paths to decide if two physically contiguous
bvec segments can be coalesced into one. It currently has no check
for whether the segments belong to different dev_pagemaps.
When zone device memory is registered in multiple chunks, each chunk
gets its own dev_pagemap. A single bio can legitimately contain
bvecs from different pgmaps -- iov_iter_extract_bvecs() breaks at
pgmap boundaries but the outer loop in bio_iov_iter_get_pages()
continues filling the same bio. If such bvecs are physically
contiguous, biovec_phys_mergeable() will coalesce them, making it
impossible to recover the correct pgmap for the merged segment
via page_pgmap().
Add a zone_device_pages_have_same_pgmap() check to prevent merging
bvec segments that span different pgmaps.
Fixes: 49580e690755 ("block: add check when merging zone device pages") Cc: stable@vger.kernel.org Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Naman Jain <namjain@linux.microsoft.com> Link: https://patch.msgid.link/20260410153414.4159050-2-namjain@linux.microsoft.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
Guangshuo Li [Wed, 15 Apr 2026 14:57:08 +0000 (22:57 +0800)]
floppy: fix reference leak on platform_device_register() failure
When platform_device_register() fails in do_floppy_init(), the embedded
struct device in floppy_device[drive] has already been initialized by
device_initialize(), but the failure path jumps to out_remove_drives
without dropping the device reference for the current drive.
Previously registered floppy devices are cleaned up in out_remove_drives,
but the device for the drive that fails registration is not, leading to
a reference leak.
The issue was identified by a static analysis tool I developed and
confirmed by manual review. Fix this by calling put_device() for the
current floppy device before jumping to the common cleanup path.
Ming Lei [Wed, 15 Apr 2026 23:02:46 +0000 (07:02 +0800)]
ublk: use unchecked copy helpers for bio page data
Bio pages may originate from slab caches that lack a usercopy region
(e.g. jbd2 frozen metadata buffers allocated via jbd2_alloc()).
When CONFIG_HARDENED_USERCOPY is enabled, copy_to_iter() calls
check_copy_size() which rejects these slab pages, triggering a
kernel BUG in usercopy_abort().
This is a false positive: the data is ordinary block I/O content —
the same data the loop driver writes to its backing file via
vfs_iter_write(). The bvec length is always trusted, so the size
check in check_copy_size() is not needed either.
Switch to _copy_to_iter()/_copy_from_iter() which skip the
check_copy_size() wrapper while the underlying copy_to_user()
remains unchanged.
Acked-by: Caleb Sander Mateos <csander@purestorage.com> Fixes: 2299ceec364e ("ublk: use copy_{to,from}_iter() for user copy") Signed-off-by: Ming Lei <ming.lei@redhat.com> Link: https://patch.msgid.link/20260415230246.808176-1-tom.leiming@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
projects / thirdparty / kernel / stable.git / log
