From: Linus Torvalds <torvalds@linux-foundation.org>
To: Hugh Dickins <hughd@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Jan Stancek <jstancek@redhat.com>,
Jakub Jelinek <jakub@redhat.com>,
David Rientjes <rientjes@google.com>,
Johannes Weiner <hannes@cmpxchg.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Ian Lance Taylor <iant@google.com>, linux-mm <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: prevent mmap_cache race in find_vma()
Date: Thu, 4 Apr 2013 11:48:01 -0700 [thread overview]
Message-ID: <CA+55aFwCG2h1ijWTCJ38LVcUyczDAfk72c4MVSU+_-BiLoMOOw@mail.gmail.com> (raw)
In-Reply-To: <alpine.LNX.2.00.1304041120510.26822@eggly.anvils>
On Thu, Apr 4, 2013 at 11:35 AM, Hugh Dickins <hughd@google.com> 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:
Ack. I do wonder if we should mark the unlocked update too some way
(also in find_vma()), although it's probably not a problem in practice
since there's no way the compiler can reasonably really do anything
odd with it. We *could* make that an ACCESS_ONCE() write too just to
highlight the fact that it's an unlocked write to this optimistic data
structure.
Anyway, applied.
Linus
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2013-04-04 18:48 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-04-04 18:35 [PATCH] mm: prevent mmap_cache race in find_vma() Hugh Dickins
2013-04-04 18:48 ` Linus Torvalds [this message]
2013-04-04 19:01 ` Hugh Dickins
2013-04-04 19:10 ` Linus Torvalds
2013-04-04 22:30 ` Paul E. McKenney
-- strict thread matches above, loose matches on Subject: below --
2013-04-02 21:59 Jan Stancek
2013-04-02 22:33 ` David Rientjes
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
2013-04-03 16:33 ` 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
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=CA+55aFwCG2h1ijWTCJ38LVcUyczDAfk72c4MVSU+_-BiLoMOOw@mail.gmail.com \
--to=torvalds@linux-foundation.org \
--cc=akpm@linux-foundation.org \
--cc=hannes@cmpxchg.org \
--cc=hughd@google.com \
--cc=iant@google.com \
--cc=jakub@redhat.com \
--cc=jstancek@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=paulmck@linux.vnet.ibm.com \
--cc=rientjes@google.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;
as well as URLs for NNTP newsgroup(s).