From: Andrew Morton <akpm@linux-foundation.org>
To: "Lorenzo Stoakes (ARM)" <ljs@kernel.org>
Cc: David Hildenbrand <david@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>, Jann Horn <jannh@google.com>,
Pedro Falcato <pfalcato@suse.de>,
"Matthew Wilcox (Oracle)" <willy@infradead.org>,
Jan Kara <jack@suse.cz>, Miaohe Lin <linmiaohe@huawei.com>,
Naoya Horiguchi <nao.horiguchi@gmail.com>,
Rik van Riel <riel@surriel.com>, Harry Yoo <harry@kernel.org>,
Lance Yang <lance.yang@linux.dev>, Kees Cook <kees@kernel.org>,
Zi Yan <ziy@nvidia.com>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
Nico Pache <npache@redhat.com>,
Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
Barry Song <baohua@kernel.org>, Usama Arif <usama.arif@linux.dev>,
Matthew Brost <matthew.brost@intel.com>,
Joshua Hahn <joshua.hahnjy@gmail.com>,
Rakie Kim <rakie.kim@sk.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>, Xu Xin <xu.xin16@zte.com.cn>,
Chengming Zhou <chengming.zhou@linux.dev>,
Arnd Bergmann <arnd@arndb.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v2 00/15] mm/rmap: index MAP_PRIVATE file-backed folios by virt pgoff
Date: Mon, 20 Jul 2026 12:48:12 -0700 [thread overview]
Message-ID: <20260720124812.30e04cc81a56dd6f0346cdf6@linux-foundation.org> (raw)
In-Reply-To: <20260720-b4-scalable-cow-virt-pgoff-v2-0-2d549757a76f@kernel.org>
On Mon, 20 Jul 2026 15:38:26 +0100 "Lorenzo Stoakes (ARM)" <ljs@kernel.org> wrote:
> In memory management we've managed to manufacture a great deal of confusion
> around the concept of anonymous memory. We have:
>
> 1. 'Pure anon' memory - anonymous VMAs whose folios are anonymous and
> swap-backed (thus for reclaim purposes, treated as anonymous). These are
> simple enough.
>
> 2. shmem - file-backed VMAs, file-backed folios (from rmap perspective) so
> present in the page cache and mapped by an address_space object, but
> whose folios are also swap-backed (thus treated as anonymous for reclaim
> purposes).
>
> 3. MAP_PRIVATE-mapped /dev/zero - a strange beast whose VMAs have
> vma->vm_file set, but whose mmap_prepare callback clears vma->vm_ops to
> satisfy vma_is_anonymous(), which results in VMAs that were mmap()'d
> referencing a file, but are in every other sense anonymous, including the
> folios.
>
> 4. Other MAP_PRIVATE-file backed mappings - These possess file-backed VMAs
> and have file-backed folios until CoW'd, at which point those CoW'd
> folios are anonymous.
>
> This series fixes issues 3 and 4.
Thanks, I'll add this to mm-new for review-n-test.
AI review seems overloaded at present, might have found a few things:
https://sashiko.dev/#/patchset/20260720-b4-scalable-cow-virt-pgoff-v2-0-2d549757a76f@kernel.org
prev parent reply other threads:[~2026-07-20 19:48 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-20 14:38 [PATCH v2 00/15] mm/rmap: index MAP_PRIVATE file-backed folios by virt pgoff Lorenzo Stoakes (ARM)
2026-07-20 14:38 ` [PATCH v2 01/15] mm/vma: introduce VMA virtual page offset field and add helpers Lorenzo Stoakes (ARM)
2026-07-20 15:49 ` Gregory Price
2026-07-20 16:56 ` Lorenzo Stoakes (ARM)
2026-07-20 17:26 ` Gregory Price
2026-07-20 14:38 ` [PATCH v2 02/15] mm: introduce linear_virt_page_index() Lorenzo Stoakes (ARM)
2026-07-20 14:38 ` [PATCH v2 03/15] mm: abstract vma_address() and introduce vma_anon_address() Lorenzo Stoakes (ARM)
2026-07-20 14:38 ` [PATCH v2 04/15] mm: update print_bad_page_map() to show virtual page index Lorenzo Stoakes (ARM)
2026-07-20 14:38 ` [PATCH v2 05/15] mm: introduce and use vma_filebacked_address() Lorenzo Stoakes (ARM)
2026-07-20 14:38 ` [PATCH v2 06/15] mm: propagate VMA virtual page offset on map, remap, split + merge Lorenzo Stoakes (ARM)
2026-07-20 14:38 ` [PATCH v2 07/15] mm/rmap: track whether the page VMA mapped walk is anonymous Lorenzo Stoakes (ARM)
2026-07-20 14:38 ` [PATCH v2 08/15] mm: introduce and use linear_folio_page_index() Lorenzo Stoakes (ARM)
2026-07-20 14:38 ` [PATCH v2 09/15] mm/rmap: use virt pgoff for MAP_PRIVATE file-backed anon folios Lorenzo Stoakes (ARM)
2026-07-20 14:38 ` [PATCH v2 10/15] tools/testing/vma: expand VMA merge tests to assert virt pgoff Lorenzo Stoakes (ARM)
2026-07-20 14:38 ` [PATCH v2 11/15] tools/testing/selftests/mm: test virtual page offset merge behaviour Lorenzo Stoakes (ARM)
2026-07-20 14:38 ` [PATCH v2 12/15] mm/vma: only permit MAP_PRIVATE /dev/zero to be mapped anonymous Lorenzo Stoakes (ARM)
2026-07-20 14:38 ` [PATCH v2 13/15] mm/vma: make MAP_PRIVATE-mapped /dev/zero mappings truly anonymous Lorenzo Stoakes (ARM)
2026-07-20 14:38 ` [PATCH v2 14/15] tools/testing/vma: add test to assert MAP_PRIVATE-/dev/zero is anon Lorenzo Stoakes (ARM)
2026-07-20 14:38 ` [PATCH v2 15/15] tools/testing/selftests/mm: add MAP_PRIVATE-/dev/zero merge tests Lorenzo Stoakes (ARM)
2026-07-20 19:48 ` Andrew Morton [this message]
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