linux-kernel - Re: [PATCH 1/1] userfaultfd: remove WRITE_ONCE when setting folio->index during UFFDIO

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Date: Mon, 15 Apr 2024 09:31:24 -0400
From: Peter Xu <peterx@...hat.com>
To: Suren Baghdasaryan <surenb@...gle.com>
Cc: akpm@...ux-foundation.org, willy@...radead.org, david@...hat.com,
	lokeshgidra@...gle.com, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] userfaultfd: remove WRITE_ONCE when setting
 folio->index during UFFDIO_MOVE

On Sun, Apr 14, 2024 at 07:08:21PM -0700, Suren Baghdasaryan wrote:
> When folio is moved with UFFDIO_MOVE it gets locked before the rmap and
> index are modified. Due to the folio lock being already held, WRITE_ONCE()
> is not needed when setting the folio index. Remove it.
> 
> Reported-by: Matthew Wilcox <willy@...radead.org>
> Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
> Cc: David Hildenbrand <david@...hat.com>
> Cc: Peter Xu <peterx@...hat.com>
> Cc: Lokesh Gidra <lokeshgidra@...gle.com>

Reviewed-by: Peter Xu <peterx@...hat.com>

-- 
Peter Xu