On 2023/1/30 16:48, Michal Hocko wrote:
On Mon 30-01-23 09:16:13, Kefeng Wang wrote:
On 2023/1/30 5:48, Andrew Morton wrote:
On Sun, 29 Jan 2023 10:44:51 +0800 Kefeng Wang <wangkefeng.wang@xxxxxxxxxx> wrote:
As commit 18365225f044 ("hwpoison, memcg: forcibly uncharge LRU pages"),
Merged in 2017.
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() to
fix it.
Reported-by: Ma Wupeng <mawupeng1@xxxxxxxxxx>
Fixes: 97b27821b485 ("writeback, memcg: Implement foreign dirty flushing")
Merged in 2019.
...
Just to make sure I understand. The page has been hwpoisoned, uncharged
but stayed in the page cache so a next page fault on the address has blowned
up?
Say we address the NULL memcg case. What is the resulting behavior?
Doesn't userspace access a poisoned page and get a silend memory
corruption?
+ Yang Shi
Check previous link[1], seems that it is a known issue, and there is a
TODO list for storage backed filesystems from Yang.
[1]
https://lore.kernel.org/all/20211020210755.23964-6-shy828301@xxxxxxxxx/T/#m1d40559ca2dcf94396df5369214288f69dec379b
