On 09/01/2016 09:12 AM, Mike Snitzer wrote:
On Thu, Sep 01 2016 at 11:50am -0400,
Mike Snitzer <snitzer@xxxxxxxxxx> wrote:
On Thu, Sep 01 2016 at 11:31am -0400,
Bart Van Assche <bart.vanassche@xxxxxxxxxxx> wrote:
On 09/01/2016 08:05 AM, Mike Snitzer wrote:
I've staged most of your changes (with slight tweaks), see:
https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/log/?h=dm-4.9
Only remaining issue is the queue dying race(s) in dm-multipath.
Thanks Mike! Two minor comments though:
* In dm_start_queue(), I think that the queue_flag_clear_unlocked()
call should be converted into queue_flag_clear() and that it should
be protected by the block layer queue lock. Every call of
queue_flag_clear_unlocked() after block device initialization has
finished is wrong if blk_cleanup_queue() can be called concurrently.
OK, I'll have a look.
Please see/test the dm-4.8 and dm-4.9 branches (dm-4.9 being rebased
ontop of dm-4.8):
https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/log/?h=dm-4.8
https://git.kernel.org/cgit/linux/kernel/git/device-mapper/linux-dm.git/log/?h=dm-4.9
Hello Mike,
The result of my tests of the dm-4.9 branch is as follows:
* With patch "dm mpath: check if path's request_queue is dying in
activate_path()" I still see every now and then that CPU usage of one of
the kworker threads jumps to 100%.
* A "if (!blk_queue_stopped(q))" test needs to be added in
dm_stop_queue() to avoid the following hang (that test was present in my
version of the patch that adds the blk_mq_{freeze,unfreeze}_queue() calls):
sysrq: SysRq : Show Blocked State
task PC stack pid father
multipathd D ffff8803c8d37b80 0 3242 1 0x00000000
Call Trace:
[<ffffffff81627087>] schedule+0x37/0x90
[<ffffffff813097e1>] blk_mq_freeze_queue_wait+0x51/0xb0
[<ffffffff8130be05>] blk_mq_freeze_queue+0x15/0x20
[<ffffffffa034d882>] dm_stop_queue+0x62/0xc0 [dm_mod]
[<ffffffffa0342a1b>] dm_swap_table+0x2fb/0x370 [dm_mod]
[<ffffffffa0347875>] dev_suspend+0x95/0x220 [dm_mod]
[<ffffffffa03480fc>] ctl_ioctl+0x1fc/0x550 [dm_mod]
[<ffffffffa034845e>] dm_ctl_ioctl+0xe/0x20 [dm_mod]
[<ffffffff811ee27f>] do_vfs_ioctl+0x8f/0x690
[<ffffffff811ee8bc>] SyS_ioctl+0x3c/0x70
[<ffffffff8162d125>] entry_SYSCALL_64_fastpath+0x18/0xa8
Thanks,
Bart.
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