From: Andrew Morton <akpm@linux-foundation.org>
To: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>,
Rik van Riel <riel@surriel.com>, Song Liu <songliubraving@fb.com>,
Kiryl Shutsemau <kas@kernel.org>,
Usama Arif <usamaarif642@gmail.com>,
David Hildenbrand <david@kernel.org>,
Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
Zi Yan <ziy@nvidia.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
"Liam R . Howlett" <Liam.Howlett@oracle.com>,
Nico Pache <npache@redhat.com>,
Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
Barry Song <baohua@kernel.org>, Lance Yang <lance.yang@linux.dev>,
Meta kernel team <kernel-team@meta.com>,
linux-mm@kvack.org, cgroups@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: khugepaged: fix NR_FILE_PAGES accounting in collapse_file()
Date: Thu, 29 Jan 2026 10:50:15 -0800 [thread overview]
Message-ID: <20260129105015.0ed043764a4ad220334b7ae1@linux-foundation.org> (raw)
In-Reply-To: <20260129184054.910897-1-shakeel.butt@linux.dev>
On Thu, 29 Jan 2026 10:40:54 -0800 Shakeel Butt <shakeel.butt@linux.dev> wrote:
> In META's fleet, we are seeing high level cgroups with zero file memcg
> stat but their descendants have non-zero file stat. This should not be
> possible. On further inspection by looking at kernel data structures
> though drgn, it was revealed that the high level cgroups have negative
> file stat which was aggregated from their children.
>
> Another interesting point was that this specific issue start happening
> more often as we started deploying thp-always more widely which
> indicates some correlation between file memory and THPs and indeed it
> was found that file memcg stat accounting is buggy in the collapse code
> path from the start.
So this has no known runtime effect apart from incorrect accounting?
> Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
Should we cc:stable?
next prev parent reply other threads:[~2026-01-29 18:50 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-01-29 18:40 Shakeel Butt
2026-01-29 18:50 ` Andrew Morton [this message]
2026-01-29 18:55 ` Shakeel Butt
2026-01-29 22:47 ` Matthew Wilcox
2026-01-30 0:47 ` Shakeel Butt
2026-01-29 22:49 ` Usama Arif
2026-01-30 0:32 ` Johannes Weiner
2026-01-30 0:50 ` Shakeel Butt
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20260129105015.0ed043764a4ad220334b7ae1@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=Liam.Howlett@oracle.com \
--cc=baohua@kernel.org \
--cc=baolin.wang@linux.alibaba.com \
--cc=cgroups@vger.kernel.org \
--cc=david@kernel.org \
--cc=dev.jain@arm.com \
--cc=hannes@cmpxchg.org \
--cc=kas@kernel.org \
--cc=kernel-team@meta.com \
--cc=lance.yang@linux.dev \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=lorenzo.stoakes@oracle.com \
--cc=npache@redhat.com \
--cc=riel@surriel.com \
--cc=ryan.roberts@arm.com \
--cc=shakeel.butt@linux.dev \
--cc=songliubraving@fb.com \
--cc=usamaarif642@gmail.com \
--cc=ziy@nvidia.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox