From: Andrew Morton <akpm@linux-foundation.org>
To: Dev Jain <dev.jain@arm.com>
Cc: david@kernel.org, ljs@kernel.org, liam@infradead.org,
vbabka@kernel.org, rppt@kernel.org, surenb@google.com,
mhocko@suse.com, kasong@tencent.com, qi.zheng@linux.dev,
shakeel.butt@linux.dev, baohua@kernel.org,
axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
riel@surriel.com, harry@kernel.org, jannh@google.com,
lance.yang@linux.dev, ryan.roberts@arm.com,
anshuman.khandual@arm.com
Subject: Re: [PATCH 0/3] Batch unmap of uffd-wp file folios
Date: Wed, 15 Jul 2026 11:58:52 -0700 [thread overview]
Message-ID: <20260715115852.a32e472d97fa182d6a5ee482@linux-foundation.org> (raw)
In-Reply-To: <20260715111839.1667914-1-dev.jain@arm.com>
On Wed, 15 Jul 2026 11:18:33 +0000 Dev Jain <dev.jain@arm.com> wrote:
> Currently, batched unmapping is supported if:
>
> 1) folio is a file folio, not belonging to uffd-wp VMA
> 2) folio is anonymous and not swapbacked (lazyfree), not belonging to
> uffd-wp VMA
>
> So the cases which are not supported are
>
> 1) folio belonging to uffd-wp VMA
> 2) folio is anonymous and swapbacked
>
> It is easy to see that this adds a lot of cognitive load while reading
> try_to_unmap_one - we need to remember throughout whether nr_pages == 1
> or > 1.
>
> The uffd-wp handling in try_to_unmap_one is regarding preserving the
> uffd-wp state for file folios via pte_install_uffd_wp_if_needed (for anon
> folio, we handle that while constructing the swap pte).
>
> Stop special casing on uffd-wp VMAs by simply adding batching support
> to pte_install_uffd_wp_if_needed.
Thanks, I'll await reviewer input on this.
Sashiko might have found a pre-existing issue:
https://sashiko.dev/#/patchset/20260715111839.1667914-1-dev.jain@arm.com
prev parent reply other threads:[~2026-07-15 18:58 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-07-15 11:18 [PATCH 0/3] Batch unmap of uffd-wp file folios Dev Jain
2026-07-15 11:18 ` [PATCH 1/3] mm/memory: move pte_install_uffd_wp_if_needed() into memory.c Dev Jain
2026-07-15 11:18 ` [PATCH 2/3] mm/memory: batch set uffd-wp markers during zapping Dev Jain
2026-07-15 11:18 ` [PATCH 3/3] mm/rmap: batch unmap file folios belonging to uffd-wp VMAs Dev Jain
2026-07-15 18:58 ` Andrew Morton [this message]
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