From: Kefeng Wang wangkefeng.wang@huawei.com
mainline inclusion from mainline-v6.2-rc7 commit ac86f547ca1002aec2ef66b9e64d03f45bbbfbb9 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I6BYND
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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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 Conflicts: include/linux/memcontrol.h Signed-off-by: Lu Jialin lujialin4@huawei.com Reviewed-by: Kefeng Wang wangkefeng.wang@huawei.com Reviewed-by: Wang Weiyang wangweiyang2@huawei.com Signed-off-by: Jialin Zhang zhangjialin11@huawei.com --- include/linux/memcontrol.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 89e4f01c5710..600cda4ea1be 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -1873,10 +1873,13 @@ void mem_cgroup_track_foreign_dirty_slowpath(struct page *page, static inline void mem_cgroup_track_foreign_dirty(struct page *page, struct bdi_writeback *wb) { + struct mem_cgroup *memcg; + if (mem_cgroup_disabled()) return;
- if (unlikely(&page_memcg(page)->css != wb->memcg_css)) + memcg = page_memcg(page); + if (unlikely(memcg && &memcg->css != wb->memcg_css)) mem_cgroup_track_foreign_dirty_slowpath(page, wb); }