From: Greg Kroah-Hartman Date: Mon, 21 Sep 2020 16:15:00 +0000 (+0200) Subject: 5.4-stable patches X-Git-Tag: v4.4.237~4 X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=c247b08b2f2d8adea221c089ebb3951654e7cd50;p=thirdparty%2Fkernel%2Fstable-queue.git 5.4-stable patches added patches: mm-memcg-fix-memcg-reclaim-soft-lockup.patch --- diff --git a/queue-5.4/mm-memcg-fix-memcg-reclaim-soft-lockup.patch b/queue-5.4/mm-memcg-fix-memcg-reclaim-soft-lockup.patch new file mode 100644 index 00000000000..ad47efebfb4 --- /dev/null +++ b/queue-5.4/mm-memcg-fix-memcg-reclaim-soft-lockup.patch @@ -0,0 +1,77 @@ +From e3336cab2579012b1e72b5265adf98e2d6e244ad Mon Sep 17 00:00:00 2001 +From: Xunlei Pang +Date: Fri, 4 Sep 2020 16:35:27 -0700 +Subject: mm: memcg: fix memcg reclaim soft lockup + +From: Xunlei Pang + +commit e3336cab2579012b1e72b5265adf98e2d6e244ad upstream. + +We've met softlockup with "CONFIG_PREEMPT_NONE=y", when the target memcg +doesn't have any reclaimable memory. + +It can be easily reproduced as below: + + watchdog: BUG: soft lockup - CPU#0 stuck for 111s![memcg_test:2204] + CPU: 0 PID: 2204 Comm: memcg_test Not tainted 5.9.0-rc2+ #12 + Call Trace: + shrink_lruvec+0x49f/0x640 + shrink_node+0x2a6/0x6f0 + do_try_to_free_pages+0xe9/0x3e0 + try_to_free_mem_cgroup_pages+0xef/0x1f0 + try_charge+0x2c1/0x750 + mem_cgroup_charge+0xd7/0x240 + __add_to_page_cache_locked+0x2fd/0x370 + add_to_page_cache_lru+0x4a/0xc0 + pagecache_get_page+0x10b/0x2f0 + filemap_fault+0x661/0xad0 + ext4_filemap_fault+0x2c/0x40 + __do_fault+0x4d/0xf9 + handle_mm_fault+0x1080/0x1790 + +It only happens on our 1-vcpu instances, because there's no chance for +oom reaper to run to reclaim the to-be-killed process. + +Add a cond_resched() at the upper shrink_node_memcgs() to solve this +issue, this will mean that we will get a scheduling point for each memcg +in the reclaimed hierarchy without any dependency on the reclaimable +memory in that memcg thus making it more predictable. + +Suggested-by: Michal Hocko +Signed-off-by: Xunlei Pang +Signed-off-by: Andrew Morton +Acked-by: Chris Down +Acked-by: Michal Hocko +Acked-by: Johannes Weiner +Link: http://lkml.kernel.org/r/1598495549-67324-1-git-send-email-xlpang@linux.alibaba.com +Signed-off-by: Linus Torvalds +Fixes: b0dedc49a2da ("mm/vmscan.c: iterate only over charged shrinkers during memcg shrink_slab()") +Cc: stable@vger.kernel.org +Signed-off-by: Julius Hemanth Pitti +Signed-off-by: Greg Kroah-Hartman +--- + mm/vmscan.c | 8 ++++++++ + 1 file changed, 8 insertions(+) + +diff --git a/mm/vmscan.c b/mm/vmscan.c +index 749d239c62b2..8b97bc615d8c 100644 +--- a/mm/vmscan.c ++++ b/mm/vmscan.c +@@ -2619,6 +2619,14 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc) + unsigned long reclaimed; + unsigned long scanned; + ++ /* ++ * This loop can become CPU-bound when target memcgs ++ * aren't eligible for reclaim - either because they ++ * don't have any reclaimable pages, or because their ++ * memory is explicitly protected. Avoid soft lockups. ++ */ ++ cond_resched(); ++ + switch (mem_cgroup_protected(target_memcg, memcg)) { + case MEMCG_PROT_MIN: + /* +-- +2.17.1 + diff --git a/queue-5.4/series b/queue-5.4/series index c129ae5ff4a..074bcbccb59 100644 --- a/queue-5.4/series +++ b/queue-5.4/series @@ -70,3 +70,4 @@ dm-dax-fix-table-reference-counts.patch mm-memory_hotplug-drain-per-cpu-pages-again-during-memory-offline.patch dm-call-proper-helper-to-determine-dax-support.patch dax-fix-compilation-for-config_dax-config_fs_dax.patch +mm-memcg-fix-memcg-reclaim-soft-lockup.patch