drivers/base/memory: make memory block get/put explicit

Rename the memory block lookup helper to make the acquired reference
explicit, add memory_block_put() to wrap put_device(), remove
find_memory_block(), and use memory_block_get() as the single block-id
based lookup interface.

This makes it clearer to callers that a successful lookup holds a
reference that must be dropped, reducing the chance of forgetting the
matching put and leaking the memory block device reference.

Link: https://lore.kernel.org/linux-mm/7887915D-E598-42B3-9AFE-BFFBACE8DE2D@linux.dev/#t
Link: https://lore.kernel.org/20260512072635.3969576-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Oscar Salvador <osalvador@suse.de>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Tested-by: Donet Tom <donettom@linux.ibm.com>
Reviewed-by: Lorenzo Stoakes <ljs@kernel.org>
Tested-by: Sumanth Korikkar <sumanthk@linux.ibm.com> #s390
Cc: Richard Cheng <icheng@nvidia.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Doug Anderson <dianders@chromium.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
index b2f14db59034cf666e6dcad129103d06cb1e8328..5d3b51081ff3b5ab6499163d9d25a1a660cd083c 100644 (file)
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -164,13 +164,7 @@ static int update_lmb_associativity_index(struct drmem_lmb *lmb)
 
 static struct memory_block *lmb_to_memblock(struct drmem_lmb *lmb)
 {
-       unsigned long section_nr;
-       struct memory_block *mem_block;
-
-       section_nr = pfn_to_section_nr(PFN_DOWN(lmb->base_addr));
-
-       mem_block = find_memory_block(section_nr);
-       return mem_block;
+       return memory_block_get(phys_to_block_id(lmb->base_addr));
 }
 
 static int get_lmb_range(u32 drc_index, int n_lmbs,
@@ -220,7 +214,7 @@ static int dlpar_change_lmb_state(struct drmem_lmb *lmb, bool online)
        else
                rc = 0;
 
-       put_device(&mem_block->dev);
+       memory_block_put(mem_block);
 
        return rc;
 }
@@ -319,12 +313,12 @@ static int dlpar_remove_lmb(struct drmem_lmb *lmb)
 
        rc = dlpar_offline_lmb(lmb);
        if (rc) {
-               put_device(&mem_block->dev);
+               memory_block_put(mem_block);
                return rc;
        }
 
        __remove_memory(lmb->base_addr, memory_block_size);
-       put_device(&mem_block->dev);
+       memory_block_put(mem_block);
 
        /* Update memory regions for memory remove */
        memblock_remove(lmb->base_addr, memory_block_size);

diff --git a/drivers/base/memory.c b/drivers/base/memory.c
index 6981b55d582ace801e413616b537bf20bcf8c45a..d31a421f74832c05c480ddbaf03425ffd0332cca 100644 (file)
--- a/drivers/base/memory.c
+++ b/drivers/base/memory.c
@@ -649,7 +649,7 @@ int __weak arch_get_memory_phys_device(unsigned long start_pfn)
  *
  * Called under device_hotplug_lock.
  */
-struct memory_block *find_memory_block_by_id(unsigned long block_id)
+struct memory_block *memory_block_get(unsigned long block_id)
 {
        struct memory_block *mem;
 
@@ -659,16 +659,6 @@ struct memory_block *find_memory_block_by_id(unsigned long block_id)
        return mem;
 }
 
-/*
- * Called under device_hotplug_lock.
- */
-struct memory_block *find_memory_block(unsigned long section_nr)
-{
-       unsigned long block_id = memory_block_id(section_nr);
-
-       return find_memory_block_by_id(block_id);
-}
-
 static struct attribute *memory_memblk_attrs[] = {
        &dev_attr_phys_index.attr,
        &dev_attr_state.attr,
@@ -701,7 +691,7 @@ static int __add_memory_block(struct memory_block *memory)
 
        ret = device_register(&memory->dev);
        if (ret) {
-               put_device(&memory->dev);
+               memory_block_put(memory);
                return ret;
        }
        ret = xa_err(xa_store(&memory_blocks, memory->dev.id, memory,
@@ -795,9 +785,9 @@ static int add_memory_block(unsigned long block_id, int nid, unsigned long state
        struct memory_block *mem;
        int ret = 0;
 
-       mem = find_memory_block_by_id(block_id);
+       mem = memory_block_get(block_id);
        if (mem) {
-               put_device(&mem->dev);
+               memory_block_put(mem);
                return -EEXIST;
        }
        mem = kzalloc_obj(*mem);
@@ -845,8 +835,8 @@ static void remove_memory_block(struct memory_block *memory)
                memory->group = NULL;
        }
 
-       /* drop the ref. we got via find_memory_block() */
-       put_device(&memory->dev);
+       /* drop the ref. we got via memory_block_get() */
+       memory_block_put(memory);
        device_unregister(&memory->dev);
 }
 
@@ -880,7 +870,7 @@ int create_memory_block_devices(unsigned long start, unsigned long size,
                end_block_id = block_id;
                for (block_id = start_block_id; block_id != end_block_id;
                     block_id++) {
-                       mem = find_memory_block_by_id(block_id);
+                       mem = memory_block_get(block_id);
                        if (WARN_ON_ONCE(!mem))
                                continue;
                        remove_memory_block(mem);
@@ -908,7 +898,7 @@ void remove_memory_block_devices(unsigned long start, unsigned long size)
                return;
 
        for (block_id = start_block_id; block_id != end_block_id; block_id++) {
-               mem = find_memory_block_by_id(block_id);
+               mem = memory_block_get(block_id);
                if (WARN_ON_ONCE(!mem))
                        continue;
                num_poisoned_pages_sub(-1UL, memblk_nr_poison(mem));
@@ -1015,12 +1005,12 @@ int walk_memory_blocks(unsigned long start, unsigned long size,
                return 0;
 
        for (block_id = start_block_id; block_id <= end_block_id; block_id++) {
-               mem = find_memory_block_by_id(block_id);
+               mem = memory_block_get(block_id);
                if (!mem)
                        continue;
 
                ret = func(mem, arg);
-               put_device(&mem->dev);
+               memory_block_put(mem);
                if (ret)
                        break;
        }
@@ -1228,22 +1218,22 @@ int walk_dynamic_memory_groups(int nid, walk_memory_groups_func_t func,
 void memblk_nr_poison_inc(unsigned long pfn)
 {
        const unsigned long block_id = pfn_to_block_id(pfn);
-       struct memory_block *mem = find_memory_block_by_id(block_id);
+       struct memory_block *mem = memory_block_get(block_id);
 
        if (mem) {
                atomic_long_inc(&mem->nr_hwpoison);
-               put_device(&mem->dev);
+               memory_block_put(mem);
        }
 }
 
 void memblk_nr_poison_sub(unsigned long pfn, long i)
 {
        const unsigned long block_id = pfn_to_block_id(pfn);
-       struct memory_block *mem = find_memory_block_by_id(block_id);
+       struct memory_block *mem = memory_block_get(block_id);
 
        if (mem) {
                atomic_long_sub(i, &mem->nr_hwpoison);
-               put_device(&mem->dev);
+               memory_block_put(mem);
        }
 }
 

diff --git a/drivers/base/node.c b/drivers/base/node.c
index f4d9a21cc24e90aa62ce2c7586178dacb2e7496e..3da91929ad4e376bf35f831b66faa56a80acd46c 100644 (file)
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -849,13 +849,13 @@ static void register_memory_blocks_under_nodes(void)
                for (block_id = start_block_id; block_id <= end_block_id; block_id++) {
                        struct memory_block *mem;
 
-                       mem = find_memory_block_by_id(block_id);
+                       mem = memory_block_get(block_id);
                        if (!mem)
                                continue;
 
                        memory_block_add_nid_early(mem, nid);
                        do_register_memory_block_under_node(nid, mem);
-                       put_device(&mem->dev);
+                       memory_block_put(mem);
                }
 
        }

diff --git a/drivers/s390/char/sclp_mem.c b/drivers/s390/char/sclp_mem.c
index 78c054e26d177fbb5d5977455cec37b9842deb0e..6df1926d4c62a12e00be0b9d1547189f1de23b27 100644 (file)
--- a/drivers/s390/char/sclp_mem.c
+++ b/drivers/s390/char/sclp_mem.c
@@ -204,7 +204,7 @@ static ssize_t sclp_config_mem_store(struct kobject *kobj, struct kobj_attribute
        addr = sclp_mem->id * block_size;
        /*
         * Hold device_hotplug_lock when adding/removing memory blocks.
-        * Additionally, also protect calls to find_memory_block() and
+        * Additionally, also protect calls to memory_block_get() and
         * sclp_attach_storage().
         */
        rc = lock_device_hotplug_sysfs();
@@ -231,20 +231,19 @@ static ssize_t sclp_config_mem_store(struct kobject *kobj, struct kobj_attribute
                        sclp_mem_change_state(addr, block_size, 0);
                        goto out_unlock;
                }
-               mem = find_memory_block(pfn_to_section_nr(PFN_DOWN(addr)));
-               put_device(&mem->dev);
+               mem = memory_block_get(phys_to_block_id(addr));
+               memory_block_put(mem);
                WRITE_ONCE(sclp_mem->config, 1);
        } else {
                if (!sclp_mem->config)
                        goto out_unlock;
-               mem = find_memory_block(pfn_to_section_nr(PFN_DOWN(addr)));
+               mem = memory_block_get(phys_to_block_id(addr));
                if (mem->state != MEM_OFFLINE) {
-                       put_device(&mem->dev);
+                       memory_block_put(mem);
                        rc = -EBUSY;
                        goto out_unlock;
                }
-               /* drop the ref just got via find_memory_block() */
-               put_device(&mem->dev);
+               memory_block_put(mem);
                sclp_mem_change_state(addr, block_size, 0);
                __remove_memory(addr, block_size);
 #ifdef CONFIG_KASAN
@@ -294,11 +293,11 @@ static ssize_t sclp_memmap_on_memory_store(struct kobject *kobj, struct kobj_att
                return rc;
        block_size = memory_block_size_bytes();
        sclp_mem = container_of(kobj, struct sclp_mem, kobj);
-       mem = find_memory_block(pfn_to_section_nr(PFN_DOWN(sclp_mem->id * block_size)));
+       mem = memory_block_get(phys_to_block_id(sclp_mem->id * block_size));
        if (!mem) {
                WRITE_ONCE(sclp_mem->memmap_on_memory, value);
        } else {
-               put_device(&mem->dev);
+               memory_block_put(mem);
                rc = -EBUSY;
        }
        unlock_device_hotplug();

diff --git a/include/linux/memory.h b/include/linux/memory.h
index 5bb5599c6b2bf409a9f28fb97f27bb7bde56f3c5..463dc02f6cff0566c1aecef42420510a773963ec 100644 (file)
--- a/include/linux/memory.h
+++ b/include/linux/memory.h
@@ -158,7 +158,11 @@ int create_memory_block_devices(unsigned long start, unsigned long size,
 void remove_memory_block_devices(unsigned long start, unsigned long size);
 extern void memory_dev_init(void);
 extern int memory_notify(enum memory_block_state state, void *v);
-extern struct memory_block *find_memory_block(unsigned long section_nr);
+struct memory_block *memory_block_get(unsigned long block_id);
+static inline void memory_block_put(struct memory_block *mem)
+{
+       put_device(&mem->dev);
+}
 typedef int (*walk_memory_blocks_func_t)(struct memory_block *, void *);
 extern int walk_memory_blocks(unsigned long start, unsigned long size,
                              void *arg, walk_memory_blocks_func_t func);
@@ -171,7 +175,6 @@ struct memory_group *memory_group_find_by_id(int mgid);
 typedef int (*walk_memory_groups_func_t)(struct memory_group *, void *);
 int walk_dynamic_memory_groups(int nid, walk_memory_groups_func_t func,
                               struct memory_group *excluded, void *arg);
-struct memory_block *find_memory_block_by_id(unsigned long block_id);
 #define hotplug_memory_notifier(fn, pri) ({            \
        static __meminitdata struct notifier_block fn##_mem_nb =\
                { .notifier_call = fn, .priority = pri };\

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index af5489f03771b91da9ee27c6aebc72b18b23ecf9..7ac19fab2263242ca19752064b825963460f2369 100644 (file)
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1423,14 +1423,13 @@ static void remove_memory_blocks_and_altmaps(u64 start, u64 size)
                struct vmem_altmap *altmap = NULL;
                struct memory_block *mem;
 
-               mem = find_memory_block(pfn_to_section_nr(PFN_DOWN(cur_start)));
+               mem = memory_block_get(phys_to_block_id(cur_start));
                if (WARN_ON_ONCE(!mem))
                        continue;
 
                altmap = mem->altmap;
                mem->altmap = NULL;
-               /* drop the ref. we got via find_memory_block() */
-               put_device(&mem->dev);
+               memory_block_put(mem);
 
                remove_memory_block_devices(cur_start, memblock_size);
                arch_remove_memory(cur_start, memblock_size, altmap, NULL);