From: Baolin Wang <baolin.wang@linux.alibaba.com>
To: Kiryl Shutsemau <kas@kernel.org>
Cc: akpm@linux-foundation.org, hughd@google.com, david@kernel.org,
ziy@nvidia.com, liam@infradead.org, nico.pache@linux.dev,
ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org,
lance.yang@linux.dev, usama.arif@linux.dev, ljs@kernel.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: shmem: ignore sysfs configs for shmem forced collapse
Date: Mon, 14 Sep 2026 10:06:57 +0800 [thread overview]
Message-ID: <a3632566-ed3b-4af8-840a-7895d0e47f14@linux.alibaba.com> (raw)
In-Reply-To: <aqPmxRkJokRyVzdU@thinkstation>
On 9/11/26 7:37 PM, Kiryl Shutsemau wrote:
> On Fri, Sep 11, 2026 at 12:04:33PM +0800, Baolin Wang wrote:
>> According to Documentation/mm/transhuge.rst, MADV_COLLAPSE is expected to
>> ignore any THP or mTHP interface settings.
>>
>> However, after commit 6beeab870e70 ("mm: shmem: move shmem_huge_global_enabled()
>> into shmem_allowable_huge_orders()"), performing MADV_COLLAPSE on shmem
>> will depend on /sys/.../hugepages-2048kB/shmem_enabled being set to "inherit"
>> (although that is the default), which can cause MADV_COLLAPSE to fail
>> unexpectedly.
>>
>> Fix this by returning the result of shmem_huge_global_enabled() directly
>> when MADV_COLLAPSE is requested, allowing PMD-order collapse while ignoring
>> shmem THP/mTHP settings.
>>
>> Fixes: 6beeab870e70 ("mm: shmem: move shmem_huge_global_enabled() into shmem_allowable_huge_orders()")
>
> Hm. I don't think it is the right Fixes tag. "No functional changes" in
> its commit message seems to be true.
>
> This might be a better fit:
>
> Fixes: 26c7d8413aaf ("mm: thp: support "THPeligible" semantics for mTHP with anonymous shmem")
Ah. You are right. Will update in v2.
>> Reported-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
>> Closes: https://lore.kernel.org/all/20260908125105.1510704-7-kirill@shutemov.name/
>> Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
>
> Thanks!
>
> Reviewed-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Thanks.
next prev parent reply other threads:[~2026-09-14 2:07 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-11 4:04 Baolin Wang
2026-09-11 11:37 ` Kiryl Shutsemau
2026-09-14 2:06 ` Baolin Wang [this message]
2026-09-11 14:34 ` Zi Yan
2026-09-11 15:47 ` Lance Yang
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=a3632566-ed3b-4af8-840a-7895d0e47f14@linux.alibaba.com \
--to=baolin.wang@linux.alibaba.com \
--cc=akpm@linux-foundation.org \
--cc=baohua@kernel.org \
--cc=david@kernel.org \
--cc=dev.jain@arm.com \
--cc=hughd@google.com \
--cc=kas@kernel.org \
--cc=lance.yang@linux.dev \
--cc=liam@infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=ljs@kernel.org \
--cc=nico.pache@linux.dev \
--cc=ryan.roberts@arm.com \
--cc=usama.arif@linux.dev \
--cc=ziy@nvidia.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®