Il 01/11/2012 23:50, Jan Kara ha scritto:
On Thu 01-11-12 15:23:25, Nikola Ciprich wrote:
Nov 1 14:23:25 vmnci22 [ 1075.178123] SysRq : Show Blocked State
Nov 1 14:23:25 vmnci22 [ 1075.180555] task PC stack pid father
Nov 1 14:23:25 vmnci22 [ 1075.180592] fsfreeze D 0000000000000000 0 4215 4195 0x00000000
Nov 1 14:23:25 vmnci22 [ 1075.180599] ffff8800090b9b28 0000000000000046 0000000000000000 ffffffff00000000
Nov 1 14:23:25 vmnci22 [ 1075.180606] 0000000000013780 ffff8800090b9fd8 ffff88000f716170 ffff88000f715e80
Nov 1 14:23:25 vmnci22 [ 1075.180612] ffff88000f715dc0 ffffffff81566080 ffff88000f716170 000000010002f405
Nov 1 14:23:25 vmnci22 [ 1075.180619] Call Trace:
Nov 1 14:23:25 vmnci22 [ 1075.180693] [<ffffffff810e2dbb>] __generic_file_aio_write+0xbb/0x420
Nov 1 14:23:25 vmnci22 [ 1075.180729] [<ffffffff81079290>] ? autoremove_wake_function+0x0/0x40
Nov 1 14:23:25 vmnci22 [ 1075.180736] [<ffffffff810e317f>] generic_file_aio_write+0x5f/0xc0
Thanks. So the system isn't really deadlocked. It's just that fsfreeze
command hangs, isn't it? OK, I understand that it's kind of incovenient
situation because every command will hang like this when the filesystem is
frozen.
Now I only have to come up with a way to improve this... It isn't quite
simple - to properly protect against freezing be have to communicate down
into generic_file_aio_write() that we want to bail out if filesystem is
frozen instead of waiting.
Honza
I saw this behavior (task-hang) when I tested the fsfreeze code. I was
writing a little patch to replace fsfreeze's wait queue with a killable
queue, in this way the user can do at least "kill -9", but since the
behavior was the same before your patch I didn't send it. I don't know
if we can break any previous behavior. The funny thing here is that it's
like if fsfreeze freezes itself :)
Marco
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