From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Baolin Wang <baolin.wang@linux.alibaba.com>, Zi Yan <ziy@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>,
Nico Pache <npache@redhat.com>, Song Liu <songliubraving@fb.com>,
Chris Mason <clm@fb.com>, David Sterba <dsterba@suse.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Lorenzo Stoakes <ljs@kernel.org>,
"Liam R. Howlett" <Liam.Howlett@oracle.com>,
Ryan Roberts <ryan.roberts@arm.com>, Dev Jain <dev.jain@arm.com>,
Barry Song <baohua@kernel.org>, Lance Yang <lance.yang@linux.dev>,
Vlastimil Babka <vbabka@kernel.org>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>, Shuah Khan <shuah@kernel.org>,
linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-kselftest@vger.kernel.org
Subject: Re: [PATCH 7.2 v2 05/12] mm/khugepaged: remove READ_ONLY_THP_FOR_FS check in hugepage_pmd_enabled()
Date: Wed, 15 Apr 2026 10:00:08 +0200 [thread overview]
Message-ID: <afe0dfb9-feeb-4243-bc4b-305e5e33b581@kernel.org> (raw)
In-Reply-To: <b7aa5515-6908-4ec6-91e9-eb79d5ef70b4@linux.alibaba.com>
On 4/15/26 08:36, Baolin Wang wrote:
>
>
> On 4/15/26 2:25 AM, Zi Yan wrote:
>> On 14 Apr 2026, at 14:14, David Hildenbrand (Arm) wrote:
>>
>>>
>>> Yeah, it would be better if we could avoid it. But the dependency on the
>>> global toggle as it is today is a bit weird.
>>>
>>>
>>> I don't think there is other interaction with FS and the global toggle
>>> besides this and the one you are adjusting, right?
>>>
>
> I'm afraid not. Please also consider the per-size mTHP interfaces. It's
> possible that hugepage_global_enabled() returns false, but
> hugepages-2048kB/enabled is set to "always", which would still allow
> khugepaged to collapse folios.
The question is really which semantics we want.
Right now, there is no way to disable khugepaged for anon pages, to just
get them during page faults.
And we are now talking about the same problem for FS: to only get them
during page faults (like we did so far without CONFIG_READ_ONLY_THP_FOR_FS).
--
Cheers,
David
next prev parent reply other threads:[~2026-04-15 8:00 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-13 19:20 [PATCH 7.2 v2 00/12] Remove read-only THP support for FSes without large folio support Zi Yan
2026-04-13 19:20 ` [PATCH 7.2 v2 01/12] mm/khugepaged: remove READ_ONLY_THP_FOR_FS check Zi Yan
2026-04-13 20:20 ` Matthew Wilcox
2026-04-13 20:34 ` Zi Yan
2026-04-14 10:19 ` David Hildenbrand (Arm)
2026-04-14 10:20 ` David Hildenbrand (Arm)
2026-04-15 6:09 ` Baolin Wang
2026-04-14 10:29 ` David Hildenbrand (Arm)
2026-04-14 15:37 ` Lance Yang
2026-04-14 15:43 ` Lance Yang
2026-04-14 15:59 ` Zi Yan
2026-04-13 19:20 ` [PATCH 7.2 v2 02/12] mm/khugepaged: add folio dirty check after try_to_unmap_flush() Zi Yan
2026-04-13 20:23 ` Matthew Wilcox
2026-04-13 20:28 ` Zi Yan
2026-04-14 10:38 ` David Hildenbrand (Arm)
2026-04-14 15:55 ` Zi Yan
2026-04-13 19:20 ` [PATCH 7.2 v2 03/12] mm/huge_memory: remove READ_ONLY_THP_FOR_FS from file_thp_enabled() Zi Yan
2026-04-14 10:40 ` David Hildenbrand (Arm)
2026-04-14 15:59 ` Zi Yan
2026-04-15 6:17 ` Baolin Wang
2026-04-13 19:20 ` [PATCH 7.2 v2 04/12] mm: remove READ_ONLY_THP_FOR_FS Kconfig option Zi Yan
2026-04-14 10:40 ` David Hildenbrand (Arm)
2026-04-15 6:20 ` Baolin Wang
2026-04-13 19:20 ` [PATCH 7.2 v2 05/12] mm/khugepaged: remove READ_ONLY_THP_FOR_FS check in hugepage_pmd_enabled() Zi Yan
2026-04-13 20:33 ` Matthew Wilcox
2026-04-13 20:42 ` Zi Yan
2026-04-14 11:02 ` David Hildenbrand (Arm)
2026-04-14 16:30 ` Zi Yan
2026-04-14 18:14 ` David Hildenbrand (Arm)
2026-04-14 18:25 ` Zi Yan
2026-04-15 6:36 ` Baolin Wang
2026-04-15 8:00 ` David Hildenbrand (Arm) [this message]
2026-04-15 9:21 ` Baolin Wang
2026-04-13 19:20 ` [PATCH 7.2 v2 06/12] mm: fs: remove filemap_nr_thps*() functions and their users Zi Yan
2026-04-13 20:35 ` Matthew Wilcox
2026-04-14 11:02 ` David Hildenbrand (Arm)
2026-04-15 6:53 ` Baolin Wang
2026-04-13 19:20 ` [PATCH 7.2 v2 07/12] fs: remove nr_thps from struct address_space Zi Yan
2026-04-13 20:38 ` Matthew Wilcox
2026-04-15 6:44 ` Baolin Wang
2026-04-13 19:20 ` [PATCH 7.2 v2 08/12] mm/huge_memory: remove folio split check for READ_ONLY_THP_FOR_FS Zi Yan
2026-04-13 20:41 ` Matthew Wilcox
2026-04-13 20:46 ` Zi Yan
2026-04-14 11:03 ` David Hildenbrand (Arm)
2026-04-15 6:47 ` Baolin Wang
2026-04-13 19:20 ` [PATCH 7.2 v2 09/12] mm/truncate: use folio_split() in truncate_inode_partial_folio() Zi Yan
2026-04-13 19:20 ` [PATCH 7.2 v2 10/12] fs/btrfs: remove a comment referring to READ_ONLY_THP_FOR_FS Zi Yan
2026-04-14 11:06 ` David Hildenbrand (Arm)
2026-04-13 19:20 ` [PATCH 7.2 v2 11/12] selftests/mm: remove READ_ONLY_THP_FOR_FS in khugepaged Zi Yan
2026-04-14 11:06 ` David Hildenbrand (Arm)
2026-04-13 19:20 ` [PATCH 7.2 v2 12/12] selftests/mm: remove READ_ONLY_THP_FOR_FS from comments in guard-regions Zi Yan
2026-04-13 20:47 ` Matthew Wilcox
2026-04-13 20:51 ` Zi Yan
2026-04-13 22:28 ` Matthew Wilcox
2026-04-14 11:09 ` David Hildenbrand (Arm)
2026-04-14 16:45 ` Zi Yan
2026-04-14 17:40 ` Matthew Wilcox
2026-04-14 17:53 ` Zi Yan
2026-04-14 11:07 ` David Hildenbrand (Arm)
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