From: "Jose A. Perez de Azpillaga" <azpijr@gmail.com>
To: "David Hildenbrand (Arm)" <david@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Lorenzo Stoakes <ljs@kernel.org>,
"Liam R. Howlett" <liam@infradead.org>,
Vlastimil Babka <vbabka@kernel.org>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
Jan Kara <jack@suse.cz>, Zi Yan <ziy@nvidia.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
Nico Pache <nico.pache@linux.dev>,
Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
Barry Song <baohua@kernel.org>, Lance Yang <lance.yang@linux.dev>,
Usama Arif <usama.arif@linux.dev>,
Kiryl Shutsemau <kas@kernel.org>,
Matthew Brost <matthew.brost@intel.com>,
Joshua Hahn <joshua.hahnjy@gmail.com>,
Byungchul Park <byungchul@sk.com>,
Gregory Price <gourry@gourry.net>,
Ying Huang <ying.huang@linux.alibaba.com>,
Alistair Popple <apopple@nvidia.com>,
Peter Xu <peterx@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Song Liu <songliubraving@fb.com>, Rik van Riel <riel@surriel.com>,
Hugh Dickins <hughd@google.com>, Will Deacon <will@kernel.org>,
"Aneesh Kumar K.V" <aneesh.kumar@kernel.org>,
Nick Piggin <npiggin@gmail.com>,
Peter Zijlstra <peterz@infradead.org>,
Jason Gunthorpe <jgg@ziepe.ca>, Kevin Tian <kevin.tian@intel.com>,
"Joerg Roedel (AMD)" <joro@8bytes.org>,
Robin Murphy <robin.murphy@arm.com>,
Steve Sistare <steven.sistare@oracle.com>,
John Hubbard <jhubbard@nvidia.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org,
iommu@lists.linux.dev, Chris Mason <mason@kernel.org>,
stable@vger.kernel.org
Subject: Re: [PATCH 3/5] mm/mmu_gather: flush pending references early before the folio limit
Date: Fri, 6 Nov 2026 10:56:11 +0100 [thread overview]
Message-ID: <e3e15340-d6c0-479b-867f-e5eeac1e0e2c@gmail.com> (raw)
In-Reply-To: <20261105-refcount_overflow_stable-v1-3-70b9c655da3e@kernel.org>
On 11/5/26 2:10 PM, David Hildenbrand (Arm) wrote:
> When a task zaps mappings (e.g., MADV_DONTNEED), it can drop the PT lock
> and defer dropping the folio references. In the meantime, page faults
> can refault pagecache folios, creating more references for the same
> folios.
>
> Let's just request a flush after enqueueing a pagecache folio whose
> refcount reached a certain threshold. Start flushing well before new
> references are refused, regardless of the caller's privileges.
>
> This is a temporary measure until we have something better.
>
> Reported-by: Chris Mason <mason@kernel.org>
> Fixes: 10ebac4f95e7 ("mm/memory: optimize unmap/zap with PTE-mapped THP")
> Cc: stable@vger.kernel.org
> Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
LGTM:
Reviewed-by: Jose A. Perez de Azpillaga <azpijr@gmail.com>
--
cheers,
jose a. p-a
next prev parent reply other threads:[~2026-11-06 9:56 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-05 13:10 [PATCH 0/5] mm: limit pagecache folio refcount David Hildenbrand (Arm)
2026-11-05 13:10 ` [PATCH 1/5] mm: limit pagecache folio refcount when mapping pages David Hildenbrand (Arm)
2026-11-06 9:11 ` Lance Yang
2026-11-06 9:42 ` Jose A. Perez de Azpillaga
2026-11-06 10:05 ` David Hildenbrand (Arm)
2026-11-06 10:06 ` Lance Yang
2026-11-06 12:38 ` Kiryl Shutsemau
2026-11-05 13:10 ` [PATCH 2/5] mm: limit pagecache folio refcount when splicing into pipes David Hildenbrand (Arm)
2026-11-06 9:50 ` Jose A. Perez de Azpillaga
2026-11-06 10:03 ` Lance Yang
2026-11-06 17:58 ` Josef Bacik
2026-11-06 20:09 ` David Hildenbrand (Arm)
2026-11-06 20:43 ` Jason Gunthorpe
2026-11-06 20:45 ` David Hildenbrand (Arm)
2026-11-05 13:10 ` [PATCH 3/5] mm/mmu_gather: flush pending references early before the folio limit David Hildenbrand (Arm)
2026-11-06 9:56 ` Jose A. Perez de Azpillaga [this message]
2026-11-06 15:15 ` Lance Yang
2026-11-05 13:10 ` [PATCH 4/5] iommufd: fix cleanup when adding memfd folio pins fails David Hildenbrand (Arm)
2026-11-06 15:39 ` Lance Yang
2026-11-06 20:46 ` Jason Gunthorpe
2026-11-05 13:10 ` [PATCH 5/5] mm/gup: limit pagecache folio refcount when grabbing references David Hildenbrand (Arm)
2026-11-06 10:13 ` Jose A. Perez de Azpillaga
2026-11-05 17:51 ` [PATCH 0/5] mm: limit pagecache folio refcount David Hildenbrand (Arm)
2026-11-06 19:49 ` Josef Bacik
2026-11-06 20:31 ` David Hildenbrand (Arm)
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