linux-kernel - Re: [PATCH v3 3/6] mm/huge_memory: respect MADV_COLLAPSE with PR_THP_DISABLE_EXCEPT

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Message-ID: <ebbac3ee-df43-4a39-95b2-53f9cdd34e16@linux.alibaba.com>
Date: Tue, 5 Aug 2025 09:49:48 +0800
From: Baolin Wang <baolin.wang@...ux.alibaba.com>
To: Usama Arif <usamaarif642@...il.com>,
 Andrew Morton <akpm@...ux-foundation.org>, david@...hat.com,
 linux-mm@...ck.org
Cc: linux-fsdevel@...r.kernel.org, corbet@....net, rppt@...nel.org,
 surenb@...gle.com, mhocko@...e.com, hannes@...xchg.org, baohua@...nel.org,
 shakeel.butt@...ux.dev, riel@...riel.com, ziy@...dia.com,
 laoar.shao@...il.com, dev.jain@....com, npache@...hat.com,
 lorenzo.stoakes@...cle.com, Liam.Howlett@...cle.com, ryan.roberts@....com,
 vbabka@...e.cz, jannh@...gle.com, Arnd Bergmann <arnd@...db.de>,
 sj@...nel.org, linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
 kernel-team@...a.com
Subject: Re: [PATCH v3 3/6] mm/huge_memory: respect MADV_COLLAPSE with
 PR_THP_DISABLE_EXCEPT_ADVISED



On 2025/8/4 23:40, Usama Arif wrote:
> From: David Hildenbrand <david@...hat.com>
> 
> Let's allow for making MADV_COLLAPSE succeed on areas that neither have
> VM_HUGEPAGE nor VM_NOHUGEPAGE when we have THP disabled
> unless explicitly advised (PR_THP_DISABLE_EXCEPT_ADVISED).
> 
> MADV_COLLAPSE is a clear advice that we want to collapse.
> 
> Note that we still respect the VM_NOHUGEPAGE flag, just like
> MADV_COLLAPSE always does. So consequently, MADV_COLLAPSE is now only
> refused on VM_NOHUGEPAGE with PR_THP_DISABLE_EXCEPT_ADVISED,
> including for shmem.
> 
> Co-developed-by: Usama Arif <usamaarif642@...il.com>
> Signed-off-by: Usama Arif <usamaarif642@...il.com>
> Signed-off-by: David Hildenbrand <david@...hat.com>
> ---

LGTM.
Reviewed-by: Baolin Wang <baolin.wang@...ux.alibaba.com>