Bug 63218

Summary:	systemd-udevd hangs with umount loop ISO
Product:	systemd	Reporter:	Alex Xu (Hello71) <alex_y_xu>
Component:	general	Assignee:	systemd-bugs
Status:	RESOLVED INVALID	QA Contact:	systemd-bugs
Severity:	normal
Priority:	medium
Version:	unspecified
Hardware:	x86-64 (AMD64)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:

Description Alex Xu (Hello71) 2013-04-06 23:34:32 UTC

# cd /tmp
# mkdir ubuntu
# modprobe loop
# mount -o ro,loop,uid=dnsmasq,gid=dnsmasq ~/Downloads/ubuntu-12.10-desktop-amd64.iso ubuntu
<access some files>
# umount ubuntu
^C^C^C^Z^Z^\^\^\<alt-tab>
# echo w > /proc/sysrq-trigger
# journalctl
...
systemd-udevd[68]: worker [1399] /devices/virtual/block/loop0 timeout; kill it
systemd-udevd[68]: seq 1114 '/devices/virtual/block/loop0' killed
kernel: SysRq : Show Blocked State
kernel:   task                        PC stack   pid father        
kernel: umount          D ffff88022fd11140     0  1398   1397 0x00000004    
kernel:  ffff8801edaf9e00 0000000000000086 ffff8801e8979200 0000000000013ea0
kernel:  ffff8801add2ffd8 ffff8801add2ffd8 ffff8801add2ffd8 ffff8801edaf9e00
kernel:  ffff8801bb8cc018 ffff8801bb8cc018 ffff8801bb8cc01c ffff8801edaf9e00
kernel: Call Trace:
kernel:  [<ffffffff813bc449>] ? __mutex_lock_slowpath+0xc9/0x140
kernel:  [<ffffffff813bbfd3>] ? mutex_lock+0x23/0x40
kernel:  [<ffffffffa057327b>] ? loop_clr_fd+0x27b/0x470 [loop]
kernel:  [<ffffffffa05734e0>] ? lo_release+0x70/0x80 [loop]
kernel:  [<ffffffff8110380c>] ? __blkdev_put+0x17c/0x1d0
kernel:  [<ffffffff813bbfc6>] ? mutex_lock+0x16/0x40
kernel:  [<ffffffff810d4f25>] ? deactivate_locked_super+0x55/0x80
kernel:  [<ffffffff810ef843>] ? sys_umount+0xa3/0x3d0
kernel:  [<ffffffff813bf192>] ? system_call_fastpath+0x16/0x1b
kernel: systemd-udevd   D ffff88022fc11140     0  1399     68 0x00000004    
kernel:  ffff8801bb785400 0000000000000086 ffff8801bb781800 00000030706f6f6c
kernel:  ffff8801add83fd8 ffff8801add83fd8 ffff8801add83fd8 ffff8801bb785400
kernel:  ffff8801bb8cc018 ffff8801bb8cc018 ffff8801bb8cc01c ffff8801bb785400
kernel: Call Trace:
kernel:  [<ffffffff813bc449>] ? __mutex_lock_slowpath+0xc9/0x140
kernel:  [<ffffffff813bbfd3>] ? mutex_lock+0x23/0x40
kernel:  [<ffffffff811039f3>] ? __blkdev_get+0x43/0x420
kernel:  [<ffffffff811040a0>] ? blkdev_get+0x2d0/0x2d0
kernel:  [<ffffffff81103f66>] ? blkdev_get+0x196/0x2d0
kernel:  [<ffffffff811040a0>] ? blkdev_get+0x2d0/0x2d0
kernel:  [<ffffffff810d110e>] ? do_dentry_open.isra.18+0x1ee/0x280
kernel:  [<ffffffff810d11b5>] ? finish_open+0x15/0x20
kernel:  [<ffffffff810e014a>] ? do_last.isra.67+0x2fa/0xbf0
kernel:  [<ffffffff810dd508>] ? link_path_walk+0x68/0x830
kernel:  [<ffffffff810e0afb>] ? path_openat.isra.68+0xbb/0x450
kernel:  [<ffffffff810b6432>] ? handle_mm_fault+0x342/0x360
kernel:  [<ffffffff810e10c4>] ? do_filp_open+0x44/0xb0
kernel:  [<ffffffff810ecce2>] ? __alloc_fd+0x42/0x110
kernel:  [<ffffffff810d23d3>] ? do_sys_open+0xf3/0x1e0
kernel:  [<ffffffff813bf192>] ? system_call_fastpath+0x16/0x1b

Don't know if this is a util-linux bug (almost certainly not), loop bug (probably not), isofs bug (maybe) or systemd bug (seems like it), but something's definitely not right here.

Comment 1 Kay Sievers 2013-04-09 14:48:53 UTC

Maybe this?

http://git.kernel.org/cgit/linux/kernel/git/axboe/linux-block.git/commit/?h=for-linus&id=c2fccc1c9f7c81700cbac2120a4ad5441dd37004

If you run a recent kernel with the broken change, please close this bug.

Thanks!

Comment 2 Alex Xu (Hello71) 2013-04-09 22:21:25 UTC

Was running from torvalds master which appears to have included 8761a3dc1f07b163414e2215a2cadbb4cfe2a107; 	c2fccc1c9f7c81700cbac2120a4ad5441dd37004 is now in. I'll close this on the basis that that was most likely the cause.

Thanks!

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