From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Zi Yan <ziy@nvidia.com>, Nico Pache <npache@redhat.com>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org,
aarcange@redhat.com, akpm@linux-foundation.org,
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Subject: Re: [PATCH mm-unstable v1 1/5] mm: consolidate anonymous folio PTE mapping into helpers
Date: Thu, 12 Feb 2026 21:13:28 +0100 [thread overview]
Message-ID: <f348e466-cebe-43f2-ba8e-6ceea16955e4@kernel.org> (raw)
In-Reply-To: <079A6B19-00E6-4895-AFF7-3F7CEED4170B@nvidia.com>
On 2/12/26 21:06, Zi Yan wrote:
> <snip>
>
>>>
>>>
>>> OK, this becomes maybe_mkwrite(pte_mkdirty(entry), vma).
>>
>> Yes, upon further investigation this does seem to slightly change the behavior.
>
> I did not notice it when I was reviewing it. ;)
>
>>
>> pte_mkdirty() is now being called unconditionally from the VM_WRITE
>> flag. I noticed other callers in the kernel doing this too.
>>
>> Is it ok to leave the pte_mkdirty() or should I go back to using
>> pte_mkwrite with the conditional guarding both mkwrite and mkdirty?
>
>
> IMHO, it is better to use the conditional guarding way.
> We reach here when userspace reads an address (VM_WRITE is not set)
> and no zero page is used. Using maybe_mkwrite(pte_mkdirty(entry), vma)
> means we will get a dirty PTE pointing to the allocated page but user
> only reads from it.
In general, it's best to not perform any such changes as part of a
bigger patch. :)
--
Cheers,
David
next prev parent reply other threads:[~2026-02-12 20:13 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-02-12 2:18 [PATCH mm-unstable v1 0/5] mm: khugepaged cleanups and mTHP prerequisites Nico Pache
2026-02-12 2:18 ` [PATCH mm-unstable v1 1/5] mm: consolidate anonymous folio PTE mapping into helpers Nico Pache
2026-02-12 14:38 ` Pedro Falcato
2026-02-12 15:55 ` Joshua Hahn
2026-02-12 19:33 ` Nico Pache
2026-02-12 16:09 ` Zi Yan
2026-02-12 19:45 ` Nico Pache
2026-02-12 20:06 ` Zi Yan
2026-02-12 20:13 ` David Hildenbrand (Arm) [this message]
2026-02-12 2:18 ` [PATCH mm-unstable v1 2/5] mm: introduce is_pmd_order helper Nico Pache
2026-02-12 14:40 ` Pedro Falcato
2026-02-12 16:11 ` Zi Yan
2026-02-12 19:45 ` David Hildenbrand (Arm)
2026-02-13 3:51 ` Barry Song
2026-02-14 7:24 ` Lance Yang
2026-02-20 10:38 ` Dev Jain
2026-02-20 10:42 ` David Hildenbrand (Arm)
2026-02-12 2:18 ` [PATCH mm-unstable v1 3/5] mm/khugepaged: define COLLAPSE_MAX_PTES_LIMIT as HPAGE_PMD_NR - 1 Nico Pache
2026-02-12 6:56 ` Vernon Yang
2026-02-12 14:45 ` Pedro Falcato
2026-02-12 16:21 ` Zi Yan
2026-02-12 19:51 ` David Hildenbrand (Arm)
2026-02-12 2:23 ` [PATCH mm-unstable v1 4/5] mm/khugepaged: rename hpage_collapse_* to collapse_* Nico Pache
2026-02-12 2:23 ` [PATCH mm-unstable v1 5/5] mm/khugepaged: unify khugepaged and madv_collapse with collapse_single_pmd() Nico Pache
2026-02-12 19:52 ` [PATCH mm-unstable v1 4/5] mm/khugepaged: rename hpage_collapse_* to collapse_* David Hildenbrand (Arm)
2026-02-12 2:25 ` [PATCH mm-unstable v1 5/5] mm/khugepaged: unify khugepaged and madv_collapse with collapse_single_pmd() Nico Pache
2026-02-12 15:33 ` Pedro Falcato
2026-02-12 17:34 ` Zi Yan
2026-02-12 20:03 ` David Hildenbrand (Arm)
2026-02-12 20:26 ` Nico Pache
2026-02-14 8:24 ` Lance Yang
2026-02-12 2:26 ` [PATCH mm-unstable v1 0/5] mm: khugepaged cleanups and mTHP prerequisites Nico Pache
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