From: David Rientjes <rientjes@google.com>
To: Jan Stancek <jstancek@redhat.com>
Cc: linux-mm@kvack.org
Subject: Re: [PATCH] mm: prevent mmap_cache race in find_vma()
Date: Tue, 2 Apr 2013 15:33:58 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.02.1304021532220.25286@chino.kir.corp.google.com> (raw)
In-Reply-To: <3ae9b7e77e8428cfeb34c28ccf4a25708cbea1be.1364938782.git.jstancek@redhat.com>
On Tue, 2 Apr 2013, Jan Stancek wrote:
> find_vma() can be called by multiple threads with read lock
> held on mm->mmap_sem and any of them can update mm->mmap_cache.
> Prevent compiler from re-fetching mm->mmap_cache, because other
> readers could update it in the meantime:
>
FWIW, ACCESS_ONCE() does not guarantee that the compiler will not refetch
mm->mmap_cache whatsoever; there is nothing that prevents this either in
the C standard. You'll be relying solely on gcc's implementation of how
it dereferences volatile-qualified pointers.
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next prev parent reply other threads:[~2013-04-02 22:34 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-02 21:59 [PATCH] mm: prevent mmap_cache race in find_vma() Jan Stancek
2013-04-02 22:33 ` David Rientjes [this message]
2013-04-02 23:09 ` Hugh Dickins
2013-04-02 23:55 ` David Rientjes
2013-04-03 3:19 ` Paul E. McKenney
2013-04-03 4:21 ` David Rientjes
2013-04-03 16:38 ` Paul E. McKenney
2013-04-03 4:14 ` Johannes Weiner
2013-04-03 4:25 ` David Rientjes
2013-04-03 4:58 ` Johannes Weiner
2013-04-03 5:13 ` David Rientjes
2013-04-03 13:45 ` Ian Lance Taylor
2013-04-03 14:33 ` Johannes Weiner
2013-04-03 23:59 ` David Rientjes
2013-04-04 0:00 ` [patch] compiler: clarify ACCESS_ONCE() relies on compiler implementation David Rientjes
2013-04-04 0:38 ` Linus Torvalds
2013-04-04 1:52 ` David Rientjes
2013-04-04 2:00 ` Linus Torvalds
2013-04-04 2:18 ` David Rientjes
2013-04-04 2:37 ` Linus Torvalds
2013-04-04 6:02 ` David Rientjes
2013-04-04 14:23 ` Linus Torvalds
2013-04-04 19:40 ` David Rientjes
2013-04-04 19:53 ` Linus Torvalds
2013-04-04 20:02 ` David Rientjes
2013-04-03 16:33 ` [PATCH] mm: prevent mmap_cache race in find_vma() Paul E. McKenney
2013-04-03 16:41 ` Paul E. McKenney
2013-04-03 17:47 ` Ian Lance Taylor
2013-04-03 22:11 ` Paul E. McKenney
2013-04-03 22:28 ` Ian Lance Taylor
2013-04-12 18:05 ` Paul E. McKenney
2013-04-03 9:37 ` Jakub Jelinek
2013-04-04 18:35 Hugh Dickins
2013-04-04 18:35 ` Hugh Dickins
2013-04-04 18:48 ` Linus Torvalds
2013-04-04 18:48 ` Linus Torvalds
2013-04-04 19:01 ` Hugh Dickins
2013-04-04 19:01 ` Hugh Dickins
2013-04-04 19:10 ` Linus Torvalds
2013-04-04 19:10 ` Linus Torvalds
2013-04-04 22:30 ` Paul E. McKenney
2013-04-04 22:30 ` Paul E. McKenney
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