From: Al Viro <viro@ZenIV.linux.org.uk>
To: Dave Jones <davej@redhat.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>
Cc: Tejun Heo <tj@kernel.org>
Subject: Re: sysfs_bin_mmap lockdep trace.
Date: Wed, 13 Nov 2013 20:10:43 +0000 [thread overview]
Message-ID: <20131113201043.GE13318@ZenIV.linux.org.uk> (raw)
In-Reply-To: <20131113184538.GA7269@redhat.com>
On Wed, Nov 13, 2013 at 01:45:38PM -0500, Dave Jones wrote:
> Al, is this one also known ? Also seen on v3.12-7033-g42a2d923cc34
Umm... I've seen something like that reported after sysfs merge went in
(right after 3.12), but I hadn't looked into details.
> -> #3 (&mm->mmap_sem){++++++}:
[sr_block_ioctl() grabs sr_mutex and does copy_from_user() under it]
> -> #2 (sr_mutex){+.+.+.}:
[sr_block_open() grabs sr_mutex under ->bd_mutex]
> -> #1 (&bdev->bd_mutex){+.+.+.}:
[sysfs_blk_trace_attr_show() grabs ->bd_mutex and is called under
sysfs_open_file ->mutex]
> -> #0 (&of->mutex){+.+.+.}:
[sysfs_open_file ->mutex is grabbed by ->mmap()]
Cute... AFAICS, it came from "sysfs: copy bin mmap support from fs/sysfs/bin.c
to fs/sysfs/file.c". The first impression is that sysfs_bin_mmap() is
checking for battr->mmap too late, but I'm not sure whether we need of->mutex
to stabilize it... Tejun, any comments?
next prev parent reply other threads:[~2013-11-13 20:10 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-13 18:45 sysfs_bin_mmap lockdep trace Dave Jones
2013-11-13 20:10 ` Al Viro [this message]
2013-11-14 5:41 ` Tejun Heo
2013-11-15 1:19 ` Dave Jones
2013-11-17 2:17 ` [PATCH] sysfs: use a separate locking class for open files depending on mmap Tejun Heo
2013-11-17 3:21 ` Dave Jones
2013-11-17 3:29 ` Tejun Heo
2013-11-18 4:45 ` Greg Kroah-Hartman
2013-11-20 6:30 ` Tejun Heo
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