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From: Oscar Salvador <osalvador@suse.de>
To: David Hildenbrand <dhildenb@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Muchun Song <muchun.song@linux.dev>,
	Vishal Moola <vishal.moola@gmail.com>
Subject: Re: [PATCH] mm/hugetlb: Move vmf_anon_prepare upfront in hugetlb_wp
Date: Mon, 27 May 2024 15:54:36 +0200	[thread overview]
Message-ID: <ZlSQnLvqIILiayiW@localhost.localdomain> (raw)
In-Reply-To: <9f3371fa-0d46-4e93-a00b-0f5cb30b58bb@redhat.com>

On Mon, May 27, 2024 at 03:17:01PM +0200, David Hildenbrand wrote:
> gup_must_unshare() without a VMA is only used for GUP-fast. Before
> triggering a page fault we always fallback to GUP-slow first, where we have
> a VMA.

I see, thanks for explaining!

> IMHO we better not make assumptions that hugetlb_wp() will always already
> have an anon VMA.

Fine by me, I just wanted to have the picture more clear, because I could not
see how we could end up in such situation, but better be safe and than sorry.

@Andrew: This fix is to avoid an issue like [1], but for hugetlb_wp().

[1] https://lore.kernel.org/linux-mm/000000000000daf1e10615e64dcb@google.com/T/
 

-- 
Oscar Salvador
SUSE Labs


  reply	other threads:[~2024-05-27 13:54 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-05-21  7:34 Oscar Salvador
2024-05-21  9:56 ` David Hildenbrand
2024-05-21 10:23   ` Oscar Salvador
2024-05-27  8:53 ` Oscar Salvador
2024-05-27 13:17   ` David Hildenbrand
2024-05-27 13:54     ` Oscar Salvador [this message]
2024-06-12 20:27 ` Oscar Salvador

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