The patch below does not apply to the 5.15-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
Possible dependencies:
ac86f547ca10 ("mm: memcg: fix NULL pointer in mem_cgroup_track_foreign_dirty_slowpath()")
203a31516616 ("mm/writeback: Add __folio_mark_dirty()")
9d8053fc7a21 ("mm/memcg: Convert mem_cgroup_track_foreign_dirty_slowpath() to folio")
a49d0c507759 ("mm/writeback: Add folio_wait_stable()")
490e016f229a ("mm/writeback: Add folio_wait_writeback()")
4268b48077e5 ("mm/filemap: Add folio_end_writeback()")
575ced1c8b0d ("mm/swap: Add folio_rotate_reclaimable()")
4e1364286d0a ("mm/filemap: Add folio_unlock()")
2f52578f9c64 ("mm/util: Add folio_mapping() and folio_file_mapping()")
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From ac86f547ca1002aec2ef66b9e64d03f45bbbfbb9 Mon Sep 17 00:00:00 2001
From: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Date: Sun, 29 Jan 2023 12:09:45 +0800
Subject: [PATCH] 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@xxxxxxxxxx
Fixes: 97b27821b485 ("writeback, memcg: Implement foreign dirty flushing")
Signed-off-by: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Reported-by: Ma Wupeng <mawupeng1@xxxxxxxxxx>
Tested-by: Miko Larsson <mikoxyzzz@xxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: Kefeng Wang <wangkefeng.wang@xxxxxxxxxx>
Cc: Ma Wupeng <mawupeng1@xxxxxxxxxx>
Cc: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
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);
}
