From: "Jose A. Perez de Azpillaga" <azpijr@gmail.com>
To: "David Hildenbrand (Arm)" <david@kernel.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>,
Andrew Morton <akpm@linux-foundation.org>,
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>,
Miklos Szeredi <miklos@szeredi.hu>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Christian Brauner <brauner@kernel.org>,
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>,
Arnd Bergmann <arnd@arndb.de>, 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>,
Josef Bacik <josef@toxicpanda.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, fuse-devel@lists.linux.dev,
linux-arch@vger.kernel.org, iommu@lists.linux.dev,
stable@vger.kernel.org
Subject: Re: [PATCH v2 5/5] mm/gup: limit pagecache folio refcount when grabbing references
Date: Mon, 9 Nov 2026 10:05:30 +0100 [thread overview]
Message-ID: <8ff83fbf-2ecb-4f9b-ac8f-ee88fece67cb@gmail.com> (raw)
In-Reply-To: <20261107-refcount_overflow_stable-v2-5-c38f6809b106@kernel.org>
On 11/7/26 11:23 PM, David Hildenbrand (Arm) wrote:
> Let's add a folio_ref_count_over_limit() check in fast and slow GUP
> before acquiring additional references or pins.
>
> Keep it simple and use the check for all folio types.
>
> Don't check capabilities with IRQs disabled, as even unaudited capability
> checks can take locks. Refuse access to the admin reserve, so GUP-fast will
> fail and fall back to GUP-slow if possible.
>
> Also propagate try_grab_folio() errors when grabbing additional
> references in __get_user_pages() and in memfd_pin_folios(), so hitting
> the limit returns -ENOMEM instead of -EFAULT and -EINVAL, respectively.
nice!
> Keep the existing invalid-refcount warnings.
>
> Fixes: 800d8c63b2e9 ("shmem: add huge pages support")
> Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS")
> Fixes: 793917d997df ("mm/readahead: Add large folio readahead")
> Cc: stable@vger.kernel.org
> Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Jose A. Perez de Azpillaga <azpijr@gmail.com>
--
cheers,
jose a. p-a
prev parent reply other threads:[~2026-11-09 9:05 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-07 22:23 [PATCH v2 0/5] mm: limit pagecache folio refcount David Hildenbrand (Arm)
2026-11-07 22:23 ` [PATCH v2 1/5] mm: limit pagecache folio refcount when mapping pages David Hildenbrand (Arm)
2026-11-09 8:35 ` Jose A. Perez de Azpillaga
2026-11-07 22:23 ` [PATCH v2 2/5] mm: limit pagecache folio refcount when splicing into pipes David Hildenbrand (Arm)
2026-11-09 8:57 ` Jose A. Perez de Azpillaga
2026-11-09 9:30 ` David Hildenbrand (Arm)
2026-11-07 22:23 ` [PATCH v2 3/5] mm/mmu_gather: flush pending references early before the folio limit David Hildenbrand (Arm)
2026-11-07 22:23 ` [PATCH v2 4/5] iommufd: fix cleanup when adding memfd folio pins fails David Hildenbrand (Arm)
2026-11-07 22:23 ` [PATCH v2 5/5] mm/gup: limit pagecache folio refcount when grabbing references David Hildenbrand (Arm)
2026-11-09 9:05 ` Jose A. Perez de Azpillaga [this message]
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