From: David Hildenbrand <david@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
Muhammad Usama Anjum <usama.anjum@collabora.com>
Subject: Re: [PATCH v1] fs/proc/task_mmu: fix PAGE_IS_PFNZERO detection for the huge zero folio
Date: Wed, 18 Jun 2025 10:56:19 +0200 [thread overview]
Message-ID: <e341d554-073c-4aa2-ab01-f9bdcd51c0f3@redhat.com> (raw)
In-Reply-To: <20250617163458.a414a62e49f029a41710c7ae@linux-foundation.org>
On 18.06.25 01:34, Andrew Morton wrote:
> On Tue, 17 Jun 2025 16:35:32 +0200 David Hildenbrand <david@redhat.com> wrote:
>
>> is_zero_pfn() does not work for the huge zero folio. Fix it by using
>> is_huge_zero_pmd().
>>
>> Found by code inspection.
>>
>> Fixes: 52526ca7fdb9 ("fs/proc/task_mmu: implement IOCTL to get and optionally clear info about PTEs")
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>
>> Signed-off-by: David Hildenbrand <david@redhat.com>
>> ---
>>
>> Probably we should Cc stable, thoughts?
>
> Depends on the userspace effects. I'm thinking these are "This can
> cause the PAGEMAP_SCAN ioctl against /proc/pid/pagemap to omit pages"
> so yup, cc:stable.
I think it will be included as PAGE_IS_PRESENT, but not as
PAGE_IS_PFNZERO. That makes it a bit harder to judge the impact.
In any case, it's a simple patch and backporting should not really be
hard (automatic).
--
Cheers,
David / dhildenb
next prev parent reply other threads:[~2025-06-18 8:56 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-17 14:35 [PATCH v1] fs/proc/task_mmu: fix PAGE_IS_PFNZERO detection for the huge zero folio David Hildenbrand
2025-06-17 23:34 ` Andrew Morton
2025-06-18 8:56 ` David Hildenbrand [this message]
2025-06-30 5:18 ` Muhammad Usama Anjum
2025-06-30 7:55 ` David Hildenbrand
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