From: Johannes Weiner <hannes@cmpxchg.org>
To: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Andrew Morton <akpm@linux-foundation.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 19:32:14 -0500 [thread overview]
Message-ID: <aXv8DjjJ3zqZEsgQ@cmpxchg.org> (raw)
In-Reply-To: <20260129184054.910897-1-shakeel.butt@linux.dev>
On Thu, Jan 29, 2026 at 10:40:54AM -0800, Shakeel Butt wrote:
> @@ -2200,8 +2200,8 @@ static enum scan_result collapse_file(struct mm_struct *mm, unsigned long addr,
> else
> lruvec_stat_mod_folio(new_folio, NR_FILE_THPS, HPAGE_PMD_NR);
>
> + lruvec_stat_mod_folio(new_folio, NR_FILE_PAGES, HPAGE_PMD_NR);
The memcg breakage is more visible, but I think this has been broken
for NUMA stats even longer. new_folio could also come from a different
node than the subpages, after all.
> if (nr_none) {
> - lruvec_stat_mod_folio(new_folio, NR_FILE_PAGES, nr_none);
> /* nr_none is always 0 for non-shmem. */
> lruvec_stat_mod_folio(new_folio, NR_SHMEM, nr_none);
So AFAICT NR_SHMEM needs the same treatment.
It looks like that's been broken since f3f0e1d2150b ("khugepaged: add
support of collapse for tmpfs/shmem pages").
Anon pages avoided this, because their accounting is done in rmap.c
when the pmd is mapped and the ptes zapped.
next prev parent reply other threads:[~2026-01-30 0:32 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
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 [this message]
2026-01-30 0:50 ` Shakeel Butt
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