From: David Hildenbrand <david@redhat.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
Matthew Wilcox <willy@infradead.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Christian Brauner <brauner@kernel.org>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
Vlastimil Babka <vbabka@suse.cz>, Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>, Rik van Riel <riel@surriel.com>,
Harry Yoo <harry.yoo@oracle.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Shakeel Butt <shakeel.butt@linux.dev>,
Baolin Wang <baolin.wang@linux.alibaba.com>,
"Darrick J. Wong" <djwong@kernel.org>,
Dave Chinner <david@fromorbit.com>, linux-mm <linux-mm@kvack.org>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-kernel@vger.kernel.org, Kiryl Shutsemau <kas@kernel.org>
Subject: Re: [PATCHv2 1/2] mm/memory: Do not populate page table entries beyond i_size
Date: Mon, 27 Oct 2025 10:34:43 +0100 [thread overview]
Message-ID: <0fd86682-0679-48ee-8622-d9d7a977d69c@redhat.com> (raw)
In-Reply-To: <ca03ba53-388d-4ac4-abf3-062dcdf6ff00@app.fastmail.com>
On 24.10.25 21:32, Kirill A. Shutemov wrote:
>
>
> On Fri, Oct 24, 2025, at 16:42, David Hildenbrand wrote:
>> On 23.10.25 11:32, Kiryl Shutsemau wrote:
>>> addr0 = addr - start * PAGE_SIZE;
>>> if (folio_within_vma(folio, vmf->vma) &&
>>> - (addr0 & PMD_MASK) == ((addr0 + folio_size(folio) - 1) & PMD_MASK)) {
>>> + (addr0 & PMD_MASK) == ((addr0 + folio_size(folio) - 1) & PMD_MASK) &&
>>
>> Isn't this just testing whether addr0 is aligned to folio_size(folio)?
>> (given that we don't support folios > PMD_SIZE), like
>>
>> IS_ALIGNED(addr0, folio_size(folio))
>
> Actually, no. VMA can be not aligned to folio_size().
Ah, I missed that we can also have folio sizes besides PMD_SIZE here.
So it's all about testing whether the complete folio would be mapped by
a single page table.
(a helper would be nice, but cannot immediately come up with a good name)
--
Cheers
David / dhildenb
next prev parent reply other threads:[~2025-10-27 9:34 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-23 9:32 [PATCHv2 0/2] Fix SIGBUS semantics with large folios Kiryl Shutsemau
2025-10-23 9:32 ` [PATCHv2 1/2] mm/memory: Do not populate page table entries beyond i_size Kiryl Shutsemau
2025-10-23 20:49 ` Andrew Morton
2025-10-23 20:54 ` David Hildenbrand
2025-10-23 21:36 ` Andrew Morton
2025-10-24 9:26 ` Kiryl Shutsemau
2025-10-26 4:54 ` Andrew Morton
2025-10-24 15:42 ` David Hildenbrand
2025-10-24 19:32 ` Kirill A. Shutemov
2025-10-27 9:34 ` David Hildenbrand [this message]
2025-10-27 8:20 ` Hugh Dickins
2025-10-27 9:14 ` Kiryl Shutsemau
2025-10-27 9:22 ` David Hildenbrand
2025-10-29 8:31 ` Hugh Dickins
2025-10-29 10:11 ` Kiryl Shutsemau
2025-10-30 5:59 ` Hugh Dickins
2025-10-30 17:08 ` Kiryl Shutsemau
2025-10-23 9:32 ` [PATCHv2 2/2] mm/truncate: Unmap large folio on split failure Kiryl Shutsemau
2025-10-23 20:56 ` Andrew Morton
2025-10-24 9:05 ` Kiryl Shutsemau
2025-10-24 15:43 ` David Hildenbrand
2025-10-27 10:10 ` Hugh Dickins
2025-10-27 10:38 ` David Hildenbrand
2025-10-27 10:40 ` Kiryl Shutsemau
2025-10-29 9:12 ` Hugh Dickins
2025-10-29 10:21 ` Kiryl Shutsemau
2025-10-29 15:19 ` Darrick J. Wong
2025-10-29 17:10 ` Kiryl Shutsemau
2025-10-23 17:47 ` [PATCHv2 0/2] Fix SIGBUS semantics with large folios Darrick J. Wong
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