On Wed, Aug 03, 2016 at 10:33:54AM +1000, Dave Chinner wrote: > Hi folks, > > Just hit a reproducable hang in generic/361. Essentially this on > a 8GB pmem device: > > mkfs.xfs -f /dev/pmem1 > mount -o dax /dev/pmem1 /mnt/scratch > xfs_io -f -c "truncate 1g" test.img > losetup -f --show /mnt/scratch/test.img > mkfs.xfs -f /dev/loop0 > > And the mkfs.xfs command hangs with a discard that never completes: > > [ 243.413918] INFO: task mkfs.xfs:5708 blocked for more than 120 seconds. > [ 243.415678] Not tainted 4.7.0-dgc+ #862 > [ 243.416772] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > [ 243.418769] mkfs.xfs D ffff880835143c18 13848 5708 5441 0x00000000 > [ 243.420620] ffff880835143c18 ffff880835143c20 ffff88083a244780 ffff8808358ba3c0 > [ 243.422636] ffff88023aa20000 ffff880835144000 7fffffffffffffff 7fffffffffffffff > [ 243.424586] ffff8808358ba3c0 00000000024000c0 ffff880835143c30 ffffffff81e5e38c > [ 243.426466] Call Trace: > [ 243.427050] [<ffffffff81e5e38c>] schedule+0x3c/0x90 > [ 243.428224] [<ffffffff81e62be5>] schedule_timeout+0x265/0x330 > [ 243.429563] [<ffffffff8109f125>] ? kvm_clock_read+0x25/0x40 > [ 243.430896] [<ffffffff8109f149>] ? kvm_clock_get_cycles+0x9/0x10 > [ 243.432360] [<ffffffff81125edc>] ? ktime_get+0x3c/0xb0 > [ 243.433556] [<ffffffff81e5db54>] io_schedule_timeout+0xa4/0x110 > [ 243.434932] [<ffffffff81e5eed6>] wait_for_completion_io+0xd6/0x110 > [ 243.436297] [<ffffffff810decd0>] ? wake_up_q+0x70/0x70 > [ 243.437436] [<ffffffff817d6f06>] submit_bio_wait+0x56/0x70 > [ 243.438671] [<ffffffff817e851a>] blkdev_issue_discard+0x6a/0xb0 > [ 243.439980] [<ffffffff810dab69>] ? __might_sleep+0x49/0x80 > [ 243.441182] [<ffffffff817eea87>] blk_ioctl_discard+0x97/0xb0 > [ 243.442370] [<ffffffff817ef7bb>] blkdev_ioctl+0x7eb/0x9a0 > [ 243.443485] [<ffffffff81236a1d>] block_ioctl+0x3d/0x50 > [ 243.444552] [<ffffffff812100df>] do_vfs_ioctl+0x8f/0x670 > [ 243.445630] [<ffffffff81002434>] ? exit_to_usermode_loop+0x94/0xb0 > [ 243.446902] [<ffffffff81210739>] SyS_ioctl+0x79/0x90 > [ 243.447927] [<ffffffff81002bc5>] ? syscall_return_slowpath+0xf5/0x190 > [ 243.449236] [<ffffffff81e63d32>] entry_SYSCALL_64_fastpath+0x1a/0xa4 > > This only reproduces when the underlying filesystem is mounted with > -o dax, so there is a bad interaction with loop devices and DAX > occurring somewhere. generic/361 is a recent test (committed june 14) > so this probably hasn't actually been tested until now. > > I haven't got time to look at this right now, hence the report. Cool, thanks for the report. I've reproduced this with linux/master, and the test passes with v4.7. Running a bisect... -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
