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authorKefeng Wang <wangkefeng.wang@huawei.com>2023-01-29 07:09:45 +0300
committerAndrew Morton <akpm@linux-foundation.org>2023-02-01 03:44:10 +0300
commitac86f547ca1002aec2ef66b9e64d03f45bbbfbb9 (patch)
treea1304e62796582cd60a90d93ca0d27a6444a5cf2
parent1e90e35b620587e82cf52f3b7ccd8270d824d840 (diff)
downloadlinux-ac86f547ca1002aec2ef66b9e64d03f45bbbfbb9.tar.xz
mm: memcg: fix NULL pointer in mem_cgroup_track_foreign_dirty_slowpath()
As commit 18365225f044 ("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: 97b27821b485 ("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>
-rw-r--r--include/linux/memcontrol.h5
1 files changed, 4 insertions, 1 deletions
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index d3c8203cab6c..85dc9b88ea37 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -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,
struct bdi_writeback *wb)
{
+ struct mem_cgroup *memcg;
+
if (mem_cgroup_disabled())
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);
}