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mm: memcg: fix NULL pointer in mem_cgroup_track_foreign_dirty_slowpath()

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As commit 18365225f0 ("hwpoison, memcg: forcibly uncharge LRU pages"),
hwpoison will forcibly uncharg a LRU hwpoisoned page, the folio_memcg
could be NULl, then, mem_cgroup_track_foreign_dirty_slowpath() could
occurs a NULL pointer dereference, let's do not record the foreign
writebacks for folio memcg is null in mem_cgroup_track_foreign_dirty() to
fix it.

Link: https://lkml.kernel.org/r/20230129040945.180629-1-wangkefeng.wang@huawei.com
Fixes: 97b27821b4 ("writeback, memcg: Implement foreign dirty flushing")
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reported-by: Ma Wupeng <mawupeng1@huawei.com>
Tested-by: Miko Larsson <mikoxyzzz@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Ma Wupeng <mawupeng1@huawei.com>
Cc: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Kefeng Wang 2023-01-29 12:09:45 +08:00 committed by Andrew Morton
parent 1e90e35b62
commit ac86f547ca
1 changed files with 4 additions and 1 deletions
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5
include/linux/memcontrol.h
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@ -1666,10 +1666,13 @@ void mem_cgroup_track_foreign_dirty_slowpath(struct folio *folio,
static inline void mem_cgroup_track_foreign_dirty(struct folio *folio, static inline void mem_cgroup_track_foreign_dirty(struct folio *folio,
struct bdi_writeback *wb) struct bdi_writeback *wb)
{ {
struct mem_cgroup *memcg;
if (mem_cgroup_disabled()) if (mem_cgroup_disabled())
return; return;
if (unlikely(&folio_memcg(folio)->css != wb->memcg_css)) memcg = folio_memcg(folio);
if (unlikely(memcg && &memcg->css != wb->memcg_css))
mem_cgroup_track_foreign_dirty_slowpath(folio, wb); mem_cgroup_track_foreign_dirty_slowpath(folio, wb);
} }