From: Kefeng Wang <wangkefeng.wang@huawei.com>
To: Michal Hocko <mhocko@suse.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Tejun Heo <tj@kernel.org>, Jens Axboe <axboe@kernel.dk>,
Jan Kara <jack@suse.cz>, Shakeel Butt <shakeelb@google.com>,
Naoya Horiguchi <naoya.horiguchi@nec.com>,
<linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
Ma Wupeng <mawupeng1@huawei.com>, <shy828301@gmail.com>
Subject: Re: [PATCH] mm: memcg: fix NULL pointer in mem_cgroup_track_foreign_dirty()
Date: Mon, 30 Jan 2023 20:20:16 +0800 [thread overview]
Message-ID: <13e4e6ee-414e-7e36-5ac1-fa0fa555ba41@huawei.com> (raw)
In-Reply-To: <Y9eEbTXNm0x0IZem@dhcp22.suse.cz>
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@huawei.com> 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@huawei.com>
>>>> 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@gmail.com/T/#m1d40559ca2dcf94396df5369214288f69dec379b
next prev parent reply other threads:[~2023-01-30 12:20 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-29 2:44 [PATCH] mm: memcg: fix NULL pointer in mem_cgroup_track_foreign_dirty() Kefeng Wang
2023-01-29 4:09 ` [PATCH resend] mm: memcg: fix NULL pointer in mem_cgroup_track_foreign_dirty_slowpath() Kefeng Wang
2023-01-29 10:38 ` mikoxyzzz
2023-01-29 21:48 ` [PATCH] mm: memcg: fix NULL pointer in mem_cgroup_track_foreign_dirty() Andrew Morton
2023-01-30 1:16 ` Kefeng Wang
2023-01-30 8:48 ` Michal Hocko
2023-01-30 12:20 ` Kefeng Wang [this message]
2023-01-30 13:02 ` Michal Hocko
2023-01-30 19:30 ` Yang Shi
2023-02-01 8:07 ` Michal Hocko
2023-02-01 17:21 ` Yang Shi
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