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mm: memcg: fix NULL pointer in mem_cgroup_track_foreign_dirty_slowpath()
commitac86f547ca
upstream. As commit18365225f0
("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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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1 changed files with 4 additions and 1 deletions
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@ -1655,10 +1655,13 @@ void mem_cgroup_track_foreign_dirty_slowpath(struct folio *folio,
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static inline void mem_cgroup_track_foreign_dirty(struct folio *folio,
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struct bdi_writeback *wb)
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{
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struct mem_cgroup *memcg;
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if (mem_cgroup_disabled())
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return;
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if (unlikely(&folio_memcg(folio)->css != wb->memcg_css))
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memcg = folio_memcg(folio);
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if (unlikely(memcg && &memcg->css != wb->memcg_css))
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mem_cgroup_track_foreign_dirty_slowpath(folio, wb);
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}
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