From: Al Viro <viro@ZenIV.linux.org.uk>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Miklos Szeredi <mszeredi@suse.cz>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: fs/dcache.c - BUG: soft lockup - CPU#5 stuck for 22s! [systemd-udevd:1667]
Date: Wed, 28 May 2014 21:14:40 +0100 [thread overview]
Message-ID: <20140528201440.GB18016@ZenIV.linux.org.uk> (raw)
In-Reply-To: <CA+55aFwmoevoA3h5AZhqtHC0kEJegb0crT_jYvXWWD3UWZt9Aw@mail.gmail.com>
On Wed, May 28, 2014 at 12:43:24PM -0700, Linus Torvalds wrote:
> It does require that the dentry shrinking code always hold the RCU
> lock for reading, because others may actually be doing the final
> dput() while the thing is on the shrinking list (and holding the RCU
> lock is what protects the entry from actually being free'd).
>
> NOTE! I don't claim that this fixes anything, but I do think that it
> makes that whole cross-thread complexity of that DCACHE_MAY_FREE go
> away. I think it's easier to understand, and it removes code in the
> process. Comments?
Unless I'm badly misreading your patch, you are calling dentry_kill()
with rcu_read_lock() held. And that can trigger all sorts of interesting
things, starting with iput() and tons of disk IO...
What am I missing here?
next prev parent reply other threads:[~2014-05-28 20:14 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-05-26 9:37 fs/dcache.c - BUG: soft lockup - CPU#5 stuck for 22s! [systemd-udevd:1667] Mika Westerberg
2014-05-26 13:57 ` Al Viro
2014-05-26 14:29 ` Mika Westerberg
2014-05-26 14:29 ` Mika Westerberg
2014-05-26 15:27 ` Al Viro
2014-05-26 16:42 ` Al Viro
2014-05-26 18:17 ` Linus Torvalds
2014-05-26 18:26 ` Al Viro
2014-05-26 20:24 ` Linus Torvalds
2014-05-27 1:40 ` Al Viro
2014-05-27 3:14 ` Al Viro
2014-05-27 4:00 ` Al Viro
2014-05-27 7:04 ` Mika Westerberg
2014-05-27 7:04 ` Mika Westerberg
2014-05-28 3:19 ` Al Viro
2014-05-28 7:37 ` Mika Westerberg
2014-05-28 11:57 ` Al Viro
2014-05-28 13:11 ` Mika Westerberg
2014-05-28 14:19 ` Al Viro
2014-05-28 18:39 ` Al Viro
2014-05-28 19:43 ` Linus Torvalds
2014-05-28 20:02 ` Linus Torvalds
2014-05-28 20:25 ` Al Viro
2014-05-29 10:42 ` Mika Westerberg
2014-05-28 20:14 ` Al Viro [this message]
2014-05-28 21:11 ` Linus Torvalds
2014-05-28 21:28 ` Al Viro
2014-05-29 3:11 ` Al Viro
2014-05-29 3:52 ` Al Viro
2014-05-29 5:34 ` Al Viro
2014-05-29 10:51 ` Mika Westerberg
2014-05-29 10:51 ` Mika Westerberg
2014-05-29 11:04 ` Mika Westerberg
2014-05-29 13:30 ` Al Viro
2014-05-29 14:56 ` Mika Westerberg
2014-05-29 15:10 ` Linus Torvalds
2014-05-29 15:44 ` Al Viro
2014-05-29 16:23 ` Al Viro
2014-05-29 16:29 ` Linus Torvalds
2014-05-29 16:53 ` Al Viro
2014-05-29 18:52 ` Al Viro
2014-05-29 19:14 ` Linus Torvalds
2014-05-30 4:50 ` Al Viro
2014-05-30 5:00 ` Linus Torvalds
2014-05-30 6:49 ` Al Viro
2014-05-30 8:12 ` Mika Westerberg
2014-05-30 15:21 ` Al Viro
2014-05-30 15:31 ` Linus Torvalds
2014-05-30 16:48 ` [git pull] " Al Viro
2014-05-30 17:14 ` Al Viro
2014-05-31 14:18 ` Josh Boyer
2014-05-31 14:48 ` Linus Torvalds
2014-05-31 14:58 ` Josh Boyer
2014-05-31 16:12 ` Josh Boyer
2014-05-30 17:15 ` Sedat Dilek
2014-05-29 4:21 ` Linus Torvalds
2014-05-29 5:16 ` Al Viro
2014-05-29 5:26 ` Al Viro
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