From: Al Viro <viro@ZenIV.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Hugh Dickins <hughd@google.com>,
Andrew Morton <akpm@linux-foundation.org>,
Nick Piggin <npiggin@kernel.dk>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH] vfs: fix race in rcu lookup of pruned dentry
Date: Mon, 18 Jul 2011 20:47:03 +0100 [thread overview]
Message-ID: <20110718194703.GI11013@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CA+55aFycZL9zAE_Qvq9LM=HpugiDuKSjdRhKG1zi=H4LnNvhVQ@mail.gmail.com>
On Mon, Jul 18, 2011 at 12:33:28PM -0700, Linus Torvalds wrote:
> Which just makes me suspect that it's *another* case of bug in the
> dentry_kill() sequence. I think the dentry_rcuwalk_barrier() thing is
> crap: it doesn't *cover* the d_inode change with the write lock, it
> just puts that "barrier" there, which is bogus. You can get a
> successful read of the changed inode without ever failing the read
> lock sequence!
Huh? We do __d_drop() in there, and do that before we start messing
with ->d_inode. And barrier here will make sure that anything that
might have found this sucker prior to that __d_drop() will fail
->d_seq check - it bumps ->d_seq by 2...
As long as ->d_inode change happens under ->d_lock and ->d_seq is
bumped along with that change, we should be fine, no?
next prev parent reply other threads:[~2011-07-18 19:47 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-07-17 21:03 [PATCH] vfs: fix race in rcu lookup of pruned dentry Hugh Dickins
2011-07-17 22:00 ` Linus Torvalds
2011-07-17 22:59 ` Linus Torvalds
2011-07-17 23:26 ` Al Viro
2011-07-17 23:16 ` Al Viro
2011-07-17 23:38 ` Linus Torvalds
2011-07-17 23:47 ` Hugh Dickins
2011-07-18 0:25 ` Al Viro
2011-07-18 1:13 ` Hugh Dickins
2011-07-18 2:08 ` Al Viro
2011-07-18 6:31 ` Linus Torvalds
2011-07-18 14:41 ` Hugh Dickins
2011-07-18 18:11 ` Linus Torvalds
2011-07-18 18:20 ` Al Viro
2011-07-18 19:08 ` Linus Torvalds
2011-07-18 19:20 ` Al Viro
2011-07-18 19:23 ` Al Viro
2011-07-18 19:34 ` Linus Torvalds
2011-07-18 19:04 ` Hugh Dickins
2011-07-18 19:33 ` Linus Torvalds
2011-07-18 19:47 ` Al Viro [this message]
2011-07-18 20:24 ` Linus Torvalds
2011-07-18 21:19 ` Hugh Dickins
2011-07-18 21:42 ` Linus Torvalds
2011-07-18 22:43 ` Hugh Dickins
2011-07-18 23:17 ` Al Viro
2011-07-18 23:21 ` Al Viro
2011-07-18 23:27 ` Linus Torvalds
2011-07-18 23:40 ` Al Viro
2011-07-19 2:07 ` Hugh Dickins
2011-07-19 2:14 ` Linus Torvalds
2011-07-19 2:17 ` Linus Torvalds
2011-07-19 2:23 ` Al Viro
2011-07-19 2:37 ` Chris Ball
2011-07-19 4:41 ` Nicolas Pitre
2011-07-19 2:21 ` Al Viro
2011-07-19 23:45 ` Al Viro
2011-07-19 23:52 ` Al Viro
2011-07-19 23:55 ` Al Viro
2011-07-20 0:47 ` NeilBrown
2011-07-20 1:40 ` Al Viro
2011-07-20 4:52 ` Linus Torvalds
2011-07-19 23:56 ` Linus Torvalds
2011-07-20 0:04 ` Al Viro
2011-07-17 23:53 ` Al Viro
2011-07-17 23:31 ` Hugh Dickins
2011-07-17 23:52 ` Linus Torvalds
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