* btrfs: hanging processes - race condition?
@ 2010-06-10 17:41 Jerome Ibanes
2010-06-11 1:12 ` Shaohua Li
0 siblings, 1 reply; 12+ messages in thread
From: Jerome Ibanes @ 2010-06-10 17:41 UTC (permalink / raw)
To: linux-btrfs
List,
I ran into a hang issue (race condition: cpu is high when the server is
idle, meaning that btrfs is hanging, and IOwait is high as well) running
2.6.34 on debian/lenny on a x86_64 server (dual Opteron 275 w/ 16GB ram).
The btrfs filesystem live on 18x300GB scsi spindles, configured as Raid-0,
as shown below:
Label: none uuid: bc6442c6-2fe2-4236-a5aa-6b7841234c52
Total devices 18 FS bytes used 2.94TB
devid 5 size 279.39GB used 208.33GB path /dev/cciss/c1d0
devid 17 size 279.39GB used 208.34GB path /dev/cciss/c1d8
devid 16 size 279.39GB used 209.33GB path /dev/cciss/c1d7
devid 4 size 279.39GB used 208.33GB path /dev/cciss/c0d4
devid 1 size 279.39GB used 233.72GB path /dev/cciss/c0d1
devid 13 size 279.39GB used 208.33GB path /dev/cciss/c1d4
devid 8 size 279.39GB used 208.33GB path /dev/cciss/c1d11
devid 12 size 279.39GB used 208.33GB path /dev/cciss/c1d3
devid 3 size 279.39GB used 208.33GB path /dev/cciss/c0d3
devid 9 size 279.39GB used 208.33GB path /dev/cciss/c1d12
devid 6 size 279.39GB used 208.33GB path /dev/cciss/c1d1
devid 11 size 279.39GB used 208.33GB path /dev/cciss/c1d2
devid 14 size 279.39GB used 208.33GB path /dev/cciss/c1d5
devid 2 size 279.39GB used 233.70GB path /dev/cciss/c0d2
devid 15 size 279.39GB used 209.33GB path /dev/cciss/c1d6
devid 10 size 279.39GB used 208.33GB path /dev/cciss/c1d13
devid 7 size 279.39GB used 208.33GB path /dev/cciss/c1d10
devid 18 size 279.39GB used 208.34GB path /dev/cciss/c1d9
Btrfs v0.19-16-g075587c-dirty
The filesystem, mounted in /mnt/btrfs is hanging, no existing or new
process can access it, however 'df' still displays the disk usage (3TB out
of 5). The disks appear to be physically healthy. Please note that a
significant number of files were placed on this filesystem, between 20 and
30 million files.
The relevant kernel messages are displayed below:
INFO: task btrfs-submit-0:4220 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
btrfs-submit- D 000000010042e12f 0 4220 2 0x00000000
ffff8803e584ac70 0000000000000046 0000000000004000 0000000000011680
ffff8803f7349fd8 ffff8803f7349fd8 ffff8803e584ac70 0000000000011680
0000000000000001 ffff8803ff99d250 ffffffff8149f020 0000000081150ab0
Call Trace:
[<ffffffff813089f3>] ? io_schedule+0x71/0xb1
[<ffffffff811470be>] ? get_request_wait+0xab/0x140
[<ffffffff810406f4>] ? autoremove_wake_function+0x0/0x2e
[<ffffffff81143a4d>] ? elv_rq_merge_ok+0x89/0x97
[<ffffffff8114a245>] ? blk_recount_segments+0x17/0x27
[<ffffffff81147429>] ? __make_request+0x2d6/0x3fc
[<ffffffff81145b16>] ? generic_make_request+0x207/0x268
[<ffffffff81145c12>] ? submit_bio+0x9b/0xa2
[<ffffffffa01aa081>] ? btrfs_requeue_work+0xd7/0xe1 [btrfs]
[<ffffffffa01a5365>] ? run_scheduled_bios+0x297/0x48f [btrfs]
[<ffffffffa01aa687>] ? worker_loop+0x17c/0x452 [btrfs]
[<ffffffffa01aa50b>] ? worker_loop+0x0/0x452 [btrfs]
[<ffffffff81040331>] ? kthread+0x79/0x81
[<ffffffff81003674>] ? kernel_thread_helper+0x4/0x10
[<ffffffff810402b8>] ? kthread+0x0/0x81
[<ffffffff81003670>] ? kernel_thread_helper+0x0/0x10
INFO: task btrfs-transacti:4230 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
btrfs-transac D 000000010042e1cc 0 4230 2 0x00000000
ffff8803e544d300 0000000000000046 0000000000004000 0000000000011680
ffff8803f3531fd8 ffff8803f3531fd8 ffff8803e544d300 0000000000011680
ffff8803fe488240 00000000000004c1 ffff8803ff8d7340 0000000381147502
Call Trace:
[<ffffffff810b4153>] ? sync_buffer+0x0/0x3f
[<ffffffff813089f3>] ? io_schedule+0x71/0xb1
[<ffffffff810b418e>] ? sync_buffer+0x3b/0x3f
[<ffffffff81308fba>] ? __wait_on_bit+0x41/0x70
[<ffffffff810b4153>] ? sync_buffer+0x0/0x3f
[<ffffffff81309054>] ? out_of_line_wait_on_bit+0x6b/0x77
[<ffffffff81040722>] ? wake_bit_function+0x0/0x23
[<ffffffffa0186635>] ? write_dev_supers+0xf3/0x225 [btrfs]
[<ffffffffa018693b>] ? write_all_supers+0x1d4/0x22c [btrfs]
[<ffffffffa01898a1>] ? btrfs_commit_transaction+0x4fe/0x5e1 [btrfs]
[<ffffffff810406f4>] ? autoremove_wake_function+0x0/0x2e
[<ffffffffa0185628>] ? transaction_kthread+0x16b/0x1fd [btrfs]
[<ffffffffa01854bd>] ? transaction_kthread+0x0/0x1fd [btrfs]
[<ffffffff81040331>] ? kthread+0x79/0x81
[<ffffffff81003674>] ? kernel_thread_helper+0x4/0x10
[<ffffffff810402b8>] ? kthread+0x0/0x81
[<ffffffff81003670>] ? kernel_thread_helper+0x0/0x10
INFO: task tar:31615 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
tar D 000000010042dee1 0 31615 4269 0x00000000
ffff8803ffa74d70 0000000000000082 0000000000004000 0000000000011680
ffff88010046dfd8 ffff88010046dfd8 ffff8803ffa74d70 0000000000011680
ffff880361cdd480 0000000161cdd480 ffff8803ff8becf0 0000000200005fff
Call Trace:
[<ffffffff8106d2af>] ? sync_page+0x0/0x45
[<ffffffff813089f3>] ? io_schedule+0x71/0xb1
[<ffffffff8106d2f0>] ? sync_page+0x41/0x45
[<ffffffff81308fba>] ? __wait_on_bit+0x41/0x70
[<ffffffff8106d483>] ? wait_on_page_bit+0x6b/0x71
[<ffffffff81040722>] ? wake_bit_function+0x0/0x23
[<ffffffffa0192917>] ? prepare_pages+0xe0/0x244 [btrfs]
[<ffffffffa017e85a>] ? btrfs_check_data_free_space+0x69/0x206 [btrfs]
[<ffffffffa0192f6a>] ? btrfs_file_write+0x405/0x711 [btrfs]
[<ffffffff811ab83d>] ? tty_write+0x213/0x22e
[<ffffffff810951b8>] ? vfs_write+0xad/0x149
[<ffffffff81095310>] ? sys_write+0x45/0x6e
[<ffffffff810028eb>] ? system_call_fastpath+0x16/0x1b
INFO: task btrfs-submit-0:4220 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
btrfs-submit- D 000000010042e12f 0 4220 2 0x00000000
ffff8803e584ac70 0000000000000046 0000000000004000 0000000000011680
ffff8803f7349fd8 ffff8803f7349fd8 ffff8803e584ac70 0000000000011680
0000000000000001 ffff8803ff99d250 ffffffff8149f020 0000000081150ab0
Call Trace:
[<ffffffff813089f3>] ? io_schedule+0x71/0xb1
[<ffffffff811470be>] ? get_request_wait+0xab/0x140
[<ffffffff810406f4>] ? autoremove_wake_function+0x0/0x2e
[<ffffffff81143a4d>] ? elv_rq_merge_ok+0x89/0x97
[<ffffffff8114a245>] ? blk_recount_segments+0x17/0x27
[<ffffffff81147429>] ? __make_request+0x2d6/0x3fc
[<ffffffff81145b16>] ? generic_make_request+0x207/0x268
[<ffffffff81145c12>] ? submit_bio+0x9b/0xa2
[<ffffffffa01aa081>] ? btrfs_requeue_work+0xd7/0xe1 [btrfs]
[<ffffffffa01a5365>] ? run_scheduled_bios+0x297/0x48f [btrfs]
[<ffffffffa01aa687>] ? worker_loop+0x17c/0x452 [btrfs]
[<ffffffffa01aa50b>] ? worker_loop+0x0/0x452 [btrfs]
[<ffffffff81040331>] ? kthread+0x79/0x81
[<ffffffff81003674>] ? kernel_thread_helper+0x4/0x10
[<ffffffff810402b8>] ? kthread+0x0/0x81
[<ffffffff81003670>] ? kernel_thread_helper+0x0/0x10
INFO: task btrfs-transacti:4230 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
btrfs-transac D 000000010042e1cc 0 4230 2 0x00000000
ffff8803e544d300 0000000000000046 0000000000004000 0000000000011680
ffff8803f3531fd8 ffff8803f3531fd8 ffff8803e544d300 0000000000011680
ffff8803fe488240 00000000000004c1 ffff8803ff8d7340 0000000381147502
Call Trace:
[<ffffffff810b4153>] ? sync_buffer+0x0/0x3f
[<ffffffff813089f3>] ? io_schedule+0x71/0xb1
[<ffffffff810b418e>] ? sync_buffer+0x3b/0x3f
[<ffffffff81308fba>] ? __wait_on_bit+0x41/0x70
[<ffffffff810b4153>] ? sync_buffer+0x0/0x3f
[<ffffffff81309054>] ? out_of_line_wait_on_bit+0x6b/0x77
[<ffffffff81040722>] ? wake_bit_function+0x0/0x23
[<ffffffffa0186635>] ? write_dev_supers+0xf3/0x225 [btrfs]
[<ffffffffa018693b>] ? write_all_supers+0x1d4/0x22c [btrfs]
[<ffffffffa01898a1>] ? btrfs_commit_transaction+0x4fe/0x5e1 [btrfs]
[<ffffffff810406f4>] ? autoremove_wake_function+0x0/0x2e
[<ffffffffa0185628>] ? transaction_kthread+0x16b/0x1fd [btrfs]
[<ffffffffa01854bd>] ? transaction_kthread+0x0/0x1fd [btrfs]
[<ffffffff81040331>] ? kthread+0x79/0x81
[<ffffffff81003674>] ? kernel_thread_helper+0x4/0x10
[<ffffffff810402b8>] ? kthread+0x0/0x81
[<ffffffff81003670>] ? kernel_thread_helper+0x0/0x10
INFO: task tar:31615 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
tar D 000000010042dee1 0 31615 4269 0x00000000
ffff8803ffa74d70 0000000000000082 0000000000004000 0000000000011680
ffff88010046dfd8 ffff88010046dfd8 ffff8803ffa74d70 0000000000011680
ffff880361cdd480 0000000161cdd480 ffff8803ff8becf0 0000000200005fff
Call Trace:
[<ffffffff8106d2af>] ? sync_page+0x0/0x45
[<ffffffff813089f3>] ? io_schedule+0x71/0xb1
[<ffffffff8106d2f0>] ? sync_page+0x41/0x45
[<ffffffff81308fba>] ? __wait_on_bit+0x41/0x70
[<ffffffff8106d483>] ? wait_on_page_bit+0x6b/0x71
[<ffffffff81040722>] ? wake_bit_function+0x0/0x23
[<ffffffffa0192917>] ? prepare_pages+0xe0/0x244 [btrfs]
[<ffffffffa017e85a>] ? btrfs_check_data_free_space+0x69/0x206 [btrfs]
[<ffffffffa0192f6a>] ? btrfs_file_write+0x405/0x711 [btrfs]
[<ffffffff811ab83d>] ? tty_write+0x213/0x22e
[<ffffffff810951b8>] ? vfs_write+0xad/0x149
[<ffffffff81095310>] ? sys_write+0x45/0x6e
[<ffffffff810028eb>] ? system_call_fastpath+0x16/0x1b
INFO: task btrfs-submit-0:4220 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
btrfs-submit- D 000000010042e12f 0 4220 2 0x00000000
ffff8803e584ac70 0000000000000046 0000000000004000 0000000000011680
ffff8803f7349fd8 ffff8803f7349fd8 ffff8803e584ac70 0000000000011680
0000000000000001 ffff8803ff99d250 ffffffff8149f020 0000000081150ab0
Call Trace:
[<ffffffff813089f3>] ? io_schedule+0x71/0xb1
[<ffffffff811470be>] ? get_request_wait+0xab/0x140
[<ffffffff810406f4>] ? autoremove_wake_function+0x0/0x2e
[<ffffffff81143a4d>] ? elv_rq_merge_ok+0x89/0x97
[<ffffffff8114a245>] ? blk_recount_segments+0x17/0x27
[<ffffffff81147429>] ? __make_request+0x2d6/0x3fc
[<ffffffff81145b16>] ? generic_make_request+0x207/0x268
[<ffffffff81145c12>] ? submit_bio+0x9b/0xa2
[<ffffffffa01aa081>] ? btrfs_requeue_work+0xd7/0xe1 [btrfs]
[<ffffffffa01a5365>] ? run_scheduled_bios+0x297/0x48f [btrfs]
[<ffffffffa01aa687>] ? worker_loop+0x17c/0x452 [btrfs]
[<ffffffffa01aa50b>] ? worker_loop+0x0/0x452 [btrfs]
[<ffffffff81040331>] ? kthread+0x79/0x81
[<ffffffff81003674>] ? kernel_thread_helper+0x4/0x10
[<ffffffff810402b8>] ? kthread+0x0/0x81
[<ffffffff81003670>] ? kernel_thread_helper+0x0/0x10
INFO: task btrfs-transacti:4230 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
btrfs-transac D 000000010042e1cc 0 4230 2 0x00000000
ffff8803e544d300 0000000000000046 0000000000004000 0000000000011680
ffff8803f3531fd8 ffff8803f3531fd8 ffff8803e544d300 0000000000011680
ffff8803fe488240 00000000000004c1 ffff8803ff8d7340 0000000381147502
Call Trace:
[<ffffffff810b4153>] ? sync_buffer+0x0/0x3f
[<ffffffff813089f3>] ? io_schedule+0x71/0xb1
[<ffffffff810b418e>] ? sync_buffer+0x3b/0x3f
[<ffffffff81308fba>] ? __wait_on_bit+0x41/0x70
[<ffffffff810b4153>] ? sync_buffer+0x0/0x3f
[<ffffffff81309054>] ? out_of_line_wait_on_bit+0x6b/0x77
[<ffffffff81040722>] ? wake_bit_function+0x0/0x23
[<ffffffffa0186635>] ? write_dev_supers+0xf3/0x225 [btrfs]
[<ffffffffa018693b>] ? write_all_supers+0x1d4/0x22c [btrfs]
[<ffffffffa01898a1>] ? btrfs_commit_transaction+0x4fe/0x5e1 [btrfs]
[<ffffffff810406f4>] ? autoremove_wake_function+0x0/0x2e
[<ffffffffa0185628>] ? transaction_kthread+0x16b/0x1fd [btrfs]
[<ffffffffa01854bd>] ? transaction_kthread+0x0/0x1fd [btrfs]
[<ffffffff81040331>] ? kthread+0x79/0x81
[<ffffffff81003674>] ? kernel_thread_helper+0x4/0x10
[<ffffffff810402b8>] ? kthread+0x0/0x81
[<ffffffff81003670>] ? kernel_thread_helper+0x0/0x10
INFO: task tar:31615 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
tar D 000000010042dee1 0 31615 4269 0x00000000
ffff8803ffa74d70 0000000000000082 0000000000004000 0000000000011680
ffff88010046dfd8 ffff88010046dfd8 ffff8803ffa74d70 0000000000011680
ffff880361cdd480 0000000161cdd480 ffff8803ff8becf0 0000000200005fff
Call Trace:
[<ffffffff8106d2af>] ? sync_page+0x0/0x45
[<ffffffff813089f3>] ? io_schedule+0x71/0xb1
[<ffffffff8106d2f0>] ? sync_page+0x41/0x45
[<ffffffff81308fba>] ? __wait_on_bit+0x41/0x70
[<ffffffff8106d483>] ? wait_on_page_bit+0x6b/0x71
[<ffffffff81040722>] ? wake_bit_function+0x0/0x23
[<ffffffffa0192917>] ? prepare_pages+0xe0/0x244 [btrfs]
[<ffffffffa017e85a>] ? btrfs_check_data_free_space+0x69/0x206 [btrfs]
[<ffffffffa0192f6a>] ? btrfs_file_write+0x405/0x711 [btrfs]
[<ffffffff811ab83d>] ? tty_write+0x213/0x22e
[<ffffffff810951b8>] ? vfs_write+0xad/0x149
[<ffffffff81095310>] ? sys_write+0x45/0x6e
[<ffffffff810028eb>] ? system_call_fastpath+0x16/0x1b
INFO: task btrfs-submit-0:4220 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
btrfs-submit- D 000000010042e12f 0 4220 2 0x00000000
ffff8803e584ac70 0000000000000046 0000000000004000 0000000000011680
ffff8803f7349fd8 ffff8803f7349fd8 ffff8803e584ac70 0000000000011680
0000000000000001 ffff8803ff99d250 ffffffff8149f020 0000000081150ab0
Call Trace:
[<ffffffff813089f3>] ? io_schedule+0x71/0xb1
[<ffffffff811470be>] ? get_request_wait+0xab/0x140
[<ffffffff810406f4>] ? autoremove_wake_function+0x0/0x2e
[<ffffffff81143a4d>] ? elv_rq_merge_ok+0x89/0x97
[<ffffffff8114a245>] ? blk_recount_segments+0x17/0x27
[<ffffffff81147429>] ? __make_request+0x2d6/0x3fc
[<ffffffff81145b16>] ? generic_make_request+0x207/0x268
[<ffffffff81145c12>] ? submit_bio+0x9b/0xa2
[<ffffffffa01aa081>] ? btrfs_requeue_work+0xd7/0xe1 [btrfs]
[<ffffffffa01a5365>] ? run_scheduled_bios+0x297/0x48f [btrfs]
[<ffffffffa01aa687>] ? worker_loop+0x17c/0x452 [btrfs]
[<ffffffffa01aa50b>] ? worker_loop+0x0/0x452 [btrfs]
[<ffffffff81040331>] ? kthread+0x79/0x81
[<ffffffff81003674>] ? kernel_thread_helper+0x4/0x10
[<ffffffff810402b8>] ? kthread+0x0/0x81
[<ffffffff81003670>] ? kernel_thread_helper+0x0/0x10
Jerome J. Ibanes
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: btrfs: hanging processes - race condition?
2010-06-10 17:41 btrfs: hanging processes - race condition? Jerome Ibanes
@ 2010-06-11 1:12 ` Shaohua Li
2010-06-11 2:32 ` Yan, Zheng
0 siblings, 1 reply; 12+ messages in thread
From: Shaohua Li @ 2010-06-11 1:12 UTC (permalink / raw)
To: Jerome Ibanes; +Cc: linux-btrfs, yanmin.zhang, tim.c.chen
On Fri, Jun 11, 2010 at 01:41:41AM +0800, Jerome Ibanes wrote:
> List,
>
> I ran into a hang issue (race condition: cpu is high when the server is
> idle, meaning that btrfs is hanging, and IOwait is high as well) running
> 2.6.34 on debian/lenny on a x86_64 server (dual Opteron 275 w/ 16GB ram).
> The btrfs filesystem live on 18x300GB scsi spindles, configured as Raid-0,
> as shown below:
>
> Label: none uuid: bc6442c6-2fe2-4236-a5aa-6b7841234c52
> Total devices 18 FS bytes used 2.94TB
> devid 5 size 279.39GB used 208.33GB path /dev/cciss/c1d0
> devid 17 size 279.39GB used 208.34GB path /dev/cciss/c1d8
> devid 16 size 279.39GB used 209.33GB path /dev/cciss/c1d7
> devid 4 size 279.39GB used 208.33GB path /dev/cciss/c0d4
> devid 1 size 279.39GB used 233.72GB path /dev/cciss/c0d1
> devid 13 size 279.39GB used 208.33GB path /dev/cciss/c1d4
> devid 8 size 279.39GB used 208.33GB path /dev/cciss/c1d11
> devid 12 size 279.39GB used 208.33GB path /dev/cciss/c1d3
> devid 3 size 279.39GB used 208.33GB path /dev/cciss/c0d3
> devid 9 size 279.39GB used 208.33GB path /dev/cciss/c1d12
> devid 6 size 279.39GB used 208.33GB path /dev/cciss/c1d1
> devid 11 size 279.39GB used 208.33GB path /dev/cciss/c1d2
> devid 14 size 279.39GB used 208.33GB path /dev/cciss/c1d5
> devid 2 size 279.39GB used 233.70GB path /dev/cciss/c0d2
> devid 15 size 279.39GB used 209.33GB path /dev/cciss/c1d6
> devid 10 size 279.39GB used 208.33GB path /dev/cciss/c1d13
> devid 7 size 279.39GB used 208.33GB path /dev/cciss/c1d10
> devid 18 size 279.39GB used 208.34GB path /dev/cciss/c1d9
> Btrfs v0.19-16-g075587c-dirty
>
> The filesystem, mounted in /mnt/btrfs is hanging, no existing or new
> process can access it, however 'df' still displays the disk usage (3TB out
> of 5). The disks appear to be physically healthy. Please note that a
> significant number of files were placed on this filesystem, between 20 and
> 30 million files.
>
> The relevant kernel messages are displayed below:
>
> INFO: task btrfs-submit-0:4220 blocked for more than 120 seconds.
> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> btrfs-submit- D 000000010042e12f 0 4220 2 0x00000000
> ffff8803e584ac70 0000000000000046 0000000000004000 0000000000011680
> ffff8803f7349fd8 ffff8803f7349fd8 ffff8803e584ac70 0000000000011680
> 0000000000000001 ffff8803ff99d250 ffffffff8149f020 0000000081150ab0
> Call Trace:
> [<ffffffff813089f3>] ? io_schedule+0x71/0xb1
> [<ffffffff811470be>] ? get_request_wait+0xab/0x140
> [<ffffffff810406f4>] ? autoremove_wake_function+0x0/0x2e
> [<ffffffff81143a4d>] ? elv_rq_merge_ok+0x89/0x97
> [<ffffffff8114a245>] ? blk_recount_segments+0x17/0x27
> [<ffffffff81147429>] ? __make_request+0x2d6/0x3fc
> [<ffffffff81145b16>] ? generic_make_request+0x207/0x268
> [<ffffffff81145c12>] ? submit_bio+0x9b/0xa2
> [<ffffffffa01aa081>] ? btrfs_requeue_work+0xd7/0xe1 [btrfs]
> [<ffffffffa01a5365>] ? run_scheduled_bios+0x297/0x48f [btrfs]
> [<ffffffffa01aa687>] ? worker_loop+0x17c/0x452 [btrfs]
> [<ffffffffa01aa50b>] ? worker_loop+0x0/0x452 [btrfs]
> [<ffffffff81040331>] ? kthread+0x79/0x81
> [<ffffffff81003674>] ? kernel_thread_helper+0x4/0x10
> [<ffffffff810402b8>] ? kthread+0x0/0x81
> [<ffffffff81003670>] ? kernel_thread_helper+0x0/0x10
This looks like the issue we saw too, http://lkml.org/lkml/2010/6/8/375.
This is reproduceable in our setup.
Thanks,
Shaohua
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: btrfs: hanging processes - race condition?
2010-06-11 1:12 ` Shaohua Li
@ 2010-06-11 2:32 ` Yan, Zheng
2010-06-13 6:50 ` Shaohua Li
2010-06-14 13:26 ` Chris Mason
0 siblings, 2 replies; 12+ messages in thread
From: Yan, Zheng @ 2010-06-11 2:32 UTC (permalink / raw)
To: Shaohua Li; +Cc: Jerome Ibanes, linux-btrfs, yanmin.zhang, tim.c.chen
On Fri, Jun 11, 2010 at 9:12 AM, Shaohua Li <shaohua.li@intel.com> wrot=
e:
> On Fri, Jun 11, 2010 at 01:41:41AM +0800, Jerome Ibanes wrote:
>> List,
>>
>> I ran into a hang issue (race condition: cpu is high when the server=
is
>> idle, meaning that btrfs is hanging, and IOwait is high as well) run=
ning
>> 2.6.34 on debian/lenny on a x86_64 server (dual Opteron 275 w/ 16GB =
ram).
>> The btrfs filesystem live on 18x300GB scsi spindles, configured as R=
aid-0,
>> as shown below:
>>
>> Label: none =A0uuid: bc6442c6-2fe2-4236-a5aa-6b7841234c52
>> =A0 =A0 =A0 =A0 =A0Total devices 18 FS bytes used 2.94TB
>> =A0 =A0 =A0 =A0 =A0devid =A0 =A05 size 279.39GB used 208.33GB path /=
dev/cciss/c1d0
>> =A0 =A0 =A0 =A0 =A0devid =A0 17 size 279.39GB used 208.34GB path /de=
v/cciss/c1d8
>> =A0 =A0 =A0 =A0 =A0devid =A0 16 size 279.39GB used 209.33GB path /de=
v/cciss/c1d7
>> =A0 =A0 =A0 =A0 =A0devid =A0 =A04 size 279.39GB used 208.33GB path /=
dev/cciss/c0d4
>> =A0 =A0 =A0 =A0 =A0devid =A0 =A01 size 279.39GB used 233.72GB path /=
dev/cciss/c0d1
>> =A0 =A0 =A0 =A0 =A0devid =A0 13 size 279.39GB used 208.33GB path /de=
v/cciss/c1d4
>> =A0 =A0 =A0 =A0 =A0devid =A0 =A08 size 279.39GB used 208.33GB path /=
dev/cciss/c1d11
>> =A0 =A0 =A0 =A0 =A0devid =A0 12 size 279.39GB used 208.33GB path /de=
v/cciss/c1d3
>> =A0 =A0 =A0 =A0 =A0devid =A0 =A03 size 279.39GB used 208.33GB path /=
dev/cciss/c0d3
>> =A0 =A0 =A0 =A0 =A0devid =A0 =A09 size 279.39GB used 208.33GB path /=
dev/cciss/c1d12
>> =A0 =A0 =A0 =A0 =A0devid =A0 =A06 size 279.39GB used 208.33GB path /=
dev/cciss/c1d1
>> =A0 =A0 =A0 =A0 =A0devid =A0 11 size 279.39GB used 208.33GB path /de=
v/cciss/c1d2
>> =A0 =A0 =A0 =A0 =A0devid =A0 14 size 279.39GB used 208.33GB path /de=
v/cciss/c1d5
>> =A0 =A0 =A0 =A0 =A0devid =A0 =A02 size 279.39GB used 233.70GB path /=
dev/cciss/c0d2
>> =A0 =A0 =A0 =A0 =A0devid =A0 15 size 279.39GB used 209.33GB path /de=
v/cciss/c1d6
>> =A0 =A0 =A0 =A0 =A0devid =A0 10 size 279.39GB used 208.33GB path /de=
v/cciss/c1d13
>> =A0 =A0 =A0 =A0 =A0devid =A0 =A07 size 279.39GB used 208.33GB path /=
dev/cciss/c1d10
>> =A0 =A0 =A0 =A0 =A0devid =A0 18 size 279.39GB used 208.34GB path /de=
v/cciss/c1d9
>> Btrfs v0.19-16-g075587c-dirty
>>
>> The filesystem, mounted in /mnt/btrfs is hanging, no existing or new
>> process can access it, however 'df' still displays the disk usage (3=
TB out
>> of 5). The disks appear to be physically healthy. Please note that a
>> significant number of files were placed on this filesystem, between =
20 and
>> 30 million files.
>>
>> The relevant kernel messages are displayed below:
>>
>> INFO: task btrfs-submit-0:4220 blocked for more than 120 seconds.
>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this mes=
sage.
>> btrfs-submit- D 000000010042e12f =A0 =A0 0 =A04220 =A0 =A0 =A02 0x00=
000000
>> =A0 ffff8803e584ac70 0000000000000046 0000000000004000 0000000000011=
680
>> =A0 ffff8803f7349fd8 ffff8803f7349fd8 ffff8803e584ac70 0000000000011=
680
>> =A0 0000000000000001 ffff8803ff99d250 ffffffff8149f020 0000000081150=
ab0
>> Call Trace:
>> =A0 [<ffffffff813089f3>] ? io_schedule+0x71/0xb1
>> =A0 [<ffffffff811470be>] ? get_request_wait+0xab/0x140
>> =A0 [<ffffffff810406f4>] ? autoremove_wake_function+0x0/0x2e
>> =A0 [<ffffffff81143a4d>] ? elv_rq_merge_ok+0x89/0x97
>> =A0 [<ffffffff8114a245>] ? blk_recount_segments+0x17/0x27
>> =A0 [<ffffffff81147429>] ? __make_request+0x2d6/0x3fc
>> =A0 [<ffffffff81145b16>] ? generic_make_request+0x207/0x268
>> =A0 [<ffffffff81145c12>] ? submit_bio+0x9b/0xa2
>> =A0 [<ffffffffa01aa081>] ? btrfs_requeue_work+0xd7/0xe1 [btrfs]
>> =A0 [<ffffffffa01a5365>] ? run_scheduled_bios+0x297/0x48f [btrfs]
>> =A0 [<ffffffffa01aa687>] ? worker_loop+0x17c/0x452 [btrfs]
>> =A0 [<ffffffffa01aa50b>] ? worker_loop+0x0/0x452 [btrfs]
>> =A0 [<ffffffff81040331>] ? kthread+0x79/0x81
>> =A0 [<ffffffff81003674>] ? kernel_thread_helper+0x4/0x10
>> =A0 [<ffffffff810402b8>] ? kthread+0x0/0x81
>> =A0 [<ffffffff81003670>] ? kernel_thread_helper+0x0/0x10
> This looks like the issue we saw too, http://lkml.org/lkml/2010/6/8/3=
75.
> This is reproduceable in our setup.
I think I know the cause of http://lkml.org/lkml/2010/6/8/375.
The code in the first do-while loop in btrfs_commit_transaction
set current process to TASK_UNINTERRUPTIBLE state, then calls
btrfs_start_delalloc_inodes, btrfs_wait_ordered_extents and
btrfs_run_ordered_operations(). All of these function may call
cond_resched().
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* Re: btrfs: hanging processes - race condition?
2010-06-11 2:32 ` Yan, Zheng
@ 2010-06-13 6:50 ` Shaohua Li
2010-06-14 13:28 ` Chris Mason
2010-06-14 13:26 ` Chris Mason
1 sibling, 1 reply; 12+ messages in thread
From: Shaohua Li @ 2010-06-13 6:50 UTC (permalink / raw)
To: Yan, Zheng , chris.mason
Cc: Jerome Ibanes, linux-btrfs, Zhang, Yanmin, Chen, Tim C
On Fri, Jun 11, 2010 at 10:32:07AM +0800, Yan, Zheng wrote:
> On Fri, Jun 11, 2010 at 9:12 AM, Shaohua Li <shaohua.li@intel.com> wr=
ote:
> > On Fri, Jun 11, 2010 at 01:41:41AM +0800, Jerome Ibanes wrote:
> >> List,
> >>
> >> I ran into a hang issue (race condition: cpu is high when the serv=
er is
> >> idle, meaning that btrfs is hanging, and IOwait is high as well) r=
unning
> >> 2.6.34 on debian/lenny on a x86_64 server (dual Opteron 275 w/ 16G=
B ram).
> >> The btrfs filesystem live on 18x300GB scsi spindles, configured as=
Raid-0,
> >> as shown below:
> >>
> >> Label: none =A0uuid: bc6442c6-2fe2-4236-a5aa-6b7841234c52
> >> =A0 =A0 =A0 =A0 =A0Total devices 18 FS bytes used 2.94TB
> >> =A0 =A0 =A0 =A0 =A0devid =A0 =A05 size 279.39GB used 208.33GB path=
/dev/cciss/c1d0
> >> =A0 =A0 =A0 =A0 =A0devid =A0 17 size 279.39GB used 208.34GB path /=
dev/cciss/c1d8
> >> =A0 =A0 =A0 =A0 =A0devid =A0 16 size 279.39GB used 209.33GB path /=
dev/cciss/c1d7
> >> =A0 =A0 =A0 =A0 =A0devid =A0 =A04 size 279.39GB used 208.33GB path=
/dev/cciss/c0d4
> >> =A0 =A0 =A0 =A0 =A0devid =A0 =A01 size 279.39GB used 233.72GB path=
/dev/cciss/c0d1
> >> =A0 =A0 =A0 =A0 =A0devid =A0 13 size 279.39GB used 208.33GB path /=
dev/cciss/c1d4
> >> =A0 =A0 =A0 =A0 =A0devid =A0 =A08 size 279.39GB used 208.33GB path=
/dev/cciss/c1d11
> >> =A0 =A0 =A0 =A0 =A0devid =A0 12 size 279.39GB used 208.33GB path /=
dev/cciss/c1d3
> >> =A0 =A0 =A0 =A0 =A0devid =A0 =A03 size 279.39GB used 208.33GB path=
/dev/cciss/c0d3
> >> =A0 =A0 =A0 =A0 =A0devid =A0 =A09 size 279.39GB used 208.33GB path=
/dev/cciss/c1d12
> >> =A0 =A0 =A0 =A0 =A0devid =A0 =A06 size 279.39GB used 208.33GB path=
/dev/cciss/c1d1
> >> =A0 =A0 =A0 =A0 =A0devid =A0 11 size 279.39GB used 208.33GB path /=
dev/cciss/c1d2
> >> =A0 =A0 =A0 =A0 =A0devid =A0 14 size 279.39GB used 208.33GB path /=
dev/cciss/c1d5
> >> =A0 =A0 =A0 =A0 =A0devid =A0 =A02 size 279.39GB used 233.70GB path=
/dev/cciss/c0d2
> >> =A0 =A0 =A0 =A0 =A0devid =A0 15 size 279.39GB used 209.33GB path /=
dev/cciss/c1d6
> >> =A0 =A0 =A0 =A0 =A0devid =A0 10 size 279.39GB used 208.33GB path /=
dev/cciss/c1d13
> >> =A0 =A0 =A0 =A0 =A0devid =A0 =A07 size 279.39GB used 208.33GB path=
/dev/cciss/c1d10
> >> =A0 =A0 =A0 =A0 =A0devid =A0 18 size 279.39GB used 208.34GB path /=
dev/cciss/c1d9
> >> Btrfs v0.19-16-g075587c-dirty
> >>
> >> The filesystem, mounted in /mnt/btrfs is hanging, no existing or n=
ew
> >> process can access it, however 'df' still displays the disk usage =
(3TB out
> >> of 5). The disks appear to be physically healthy. Please note that=
a
> >> significant number of files were placed on this filesystem, betwee=
n 20 and
> >> 30 million files.
> >>
> >> The relevant kernel messages are displayed below:
> >>
> >> INFO: task btrfs-submit-0:4220 blocked for more than 120 seconds.
> >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this m=
essage.
> >> btrfs-submit- D 000000010042e12f =A0 =A0 0 =A04220 =A0 =A0 =A02 0x=
00000000
> >> =A0 ffff8803e584ac70 0000000000000046 0000000000004000 00000000000=
11680
> >> =A0 ffff8803f7349fd8 ffff8803f7349fd8 ffff8803e584ac70 00000000000=
11680
> >> =A0 0000000000000001 ffff8803ff99d250 ffffffff8149f020 00000000811=
50ab0
> >> Call Trace:
> >> =A0 [<ffffffff813089f3>] ? io_schedule+0x71/0xb1
> >> =A0 [<ffffffff811470be>] ? get_request_wait+0xab/0x140
> >> =A0 [<ffffffff810406f4>] ? autoremove_wake_function+0x0/0x2e
> >> =A0 [<ffffffff81143a4d>] ? elv_rq_merge_ok+0x89/0x97
> >> =A0 [<ffffffff8114a245>] ? blk_recount_segments+0x17/0x27
> >> =A0 [<ffffffff81147429>] ? __make_request+0x2d6/0x3fc
> >> =A0 [<ffffffff81145b16>] ? generic_make_request+0x207/0x268
> >> =A0 [<ffffffff81145c12>] ? submit_bio+0x9b/0xa2
> >> =A0 [<ffffffffa01aa081>] ? btrfs_requeue_work+0xd7/0xe1 [btrfs]
> >> =A0 [<ffffffffa01a5365>] ? run_scheduled_bios+0x297/0x48f [btrfs]
> >> =A0 [<ffffffffa01aa687>] ? worker_loop+0x17c/0x452 [btrfs]
> >> =A0 [<ffffffffa01aa50b>] ? worker_loop+0x0/0x452 [btrfs]
> >> =A0 [<ffffffff81040331>] ? kthread+0x79/0x81
> >> =A0 [<ffffffff81003674>] ? kernel_thread_helper+0x4/0x10
> >> =A0 [<ffffffff810402b8>] ? kthread+0x0/0x81
> >> =A0 [<ffffffff81003670>] ? kernel_thread_helper+0x0/0x10
> > This looks like the issue we saw too, http://lkml.org/lkml/2010/6/8=
/375.
> > This is reproduceable in our setup.
>=20
> I think I know the cause of http://lkml.org/lkml/2010/6/8/375.
> The code in the first do-while loop in btrfs_commit_transaction
> set current process to TASK_UNINTERRUPTIBLE state, then calls
> btrfs_start_delalloc_inodes, btrfs_wait_ordered_extents and
> btrfs_run_ordered_operations(). All of these function may call
> cond_resched().
Hi,
When I test random write, I saw a lot of threads jump into btree_writep=
ages()
and do noting and io throughput is zero for some time. Looks like there=
is a
live lock. See the code of btree_writepages():
if (wbc->sync_mode =3D=3D WB_SYNC_NONE) {
struct btrfs_root *root =3D BTRFS_I(mapping->host)->root;
u64 num_dirty;
unsigned long thresh =3D 32 * 1024 * 1024;
if (wbc->for_kupdate)
return 0;
/* this is a bit racy, but that's ok */
num_dirty =3D root->fs_info->dirty_metadata_bytes;
>>>>>> if (num_dirty < thresh)
return 0;
}
The marked line is quite intrusive. In my test, the live lock is caused=
by the thresh
check. The dirty_metadata_bytes < 32M. Without it, I can't see the live=
lock. Not
sure if this is related to the hang.
Thanks,
Shaohua
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* Re: btrfs: hanging processes - race condition?
2010-06-11 2:32 ` Yan, Zheng
2010-06-13 6:50 ` Shaohua Li
@ 2010-06-14 13:26 ` Chris Mason
1 sibling, 0 replies; 12+ messages in thread
From: Chris Mason @ 2010-06-14 13:26 UTC (permalink / raw)
To: Yan, Zheng
Cc: Shaohua Li, Jerome Ibanes, linux-btrfs, yanmin.zhang, tim.c.chen
On Fri, Jun 11, 2010 at 10:32:07AM +0800, Yan, Zheng wrote:
> On Fri, Jun 11, 2010 at 9:12 AM, Shaohua Li <shaohua.li@intel.com> wr=
ote:
> > On Fri, Jun 11, 2010 at 01:41:41AM +0800, Jerome Ibanes wrote:
> >> List,
> >>
> >> I ran into a hang issue (race condition: cpu is high when the serv=
er is
> >> idle, meaning that btrfs is hanging, and IOwait is high as well) r=
unning
> >> 2.6.34 on debian/lenny on a x86_64 server (dual Opteron 275 w/ 16G=
B ram).
> >> The btrfs filesystem live on 18x300GB scsi spindles, configured as=
Raid-0,
> >> as shown below:
> >>
> >> Label: none =A0uuid: bc6442c6-2fe2-4236-a5aa-6b7841234c52
> >> =A0 =A0 =A0 =A0 =A0Total devices 18 FS bytes used 2.94TB
> >> =A0 =A0 =A0 =A0 =A0devid =A0 =A05 size 279.39GB used 208.33GB path=
/dev/cciss/c1d0
> >> =A0 =A0 =A0 =A0 =A0devid =A0 17 size 279.39GB used 208.34GB path /=
dev/cciss/c1d8
> >> =A0 =A0 =A0 =A0 =A0devid =A0 16 size 279.39GB used 209.33GB path /=
dev/cciss/c1d7
> >> =A0 =A0 =A0 =A0 =A0devid =A0 =A04 size 279.39GB used 208.33GB path=
/dev/cciss/c0d4
> >> =A0 =A0 =A0 =A0 =A0devid =A0 =A01 size 279.39GB used 233.72GB path=
/dev/cciss/c0d1
> >> =A0 =A0 =A0 =A0 =A0devid =A0 13 size 279.39GB used 208.33GB path /=
dev/cciss/c1d4
> >> =A0 =A0 =A0 =A0 =A0devid =A0 =A08 size 279.39GB used 208.33GB path=
/dev/cciss/c1d11
> >> =A0 =A0 =A0 =A0 =A0devid =A0 12 size 279.39GB used 208.33GB path /=
dev/cciss/c1d3
> >> =A0 =A0 =A0 =A0 =A0devid =A0 =A03 size 279.39GB used 208.33GB path=
/dev/cciss/c0d3
> >> =A0 =A0 =A0 =A0 =A0devid =A0 =A09 size 279.39GB used 208.33GB path=
/dev/cciss/c1d12
> >> =A0 =A0 =A0 =A0 =A0devid =A0 =A06 size 279.39GB used 208.33GB path=
/dev/cciss/c1d1
> >> =A0 =A0 =A0 =A0 =A0devid =A0 11 size 279.39GB used 208.33GB path /=
dev/cciss/c1d2
> >> =A0 =A0 =A0 =A0 =A0devid =A0 14 size 279.39GB used 208.33GB path /=
dev/cciss/c1d5
> >> =A0 =A0 =A0 =A0 =A0devid =A0 =A02 size 279.39GB used 233.70GB path=
/dev/cciss/c0d2
> >> =A0 =A0 =A0 =A0 =A0devid =A0 15 size 279.39GB used 209.33GB path /=
dev/cciss/c1d6
> >> =A0 =A0 =A0 =A0 =A0devid =A0 10 size 279.39GB used 208.33GB path /=
dev/cciss/c1d13
> >> =A0 =A0 =A0 =A0 =A0devid =A0 =A07 size 279.39GB used 208.33GB path=
/dev/cciss/c1d10
> >> =A0 =A0 =A0 =A0 =A0devid =A0 18 size 279.39GB used 208.34GB path /=
dev/cciss/c1d9
> >> Btrfs v0.19-16-g075587c-dirty
> >>
> >> The filesystem, mounted in /mnt/btrfs is hanging, no existing or n=
ew
> >> process can access it, however 'df' still displays the disk usage =
(3TB out
> >> of 5). The disks appear to be physically healthy. Please note that=
a
> >> significant number of files were placed on this filesystem, betwee=
n 20 and
> >> 30 million files.
> >>
> >> The relevant kernel messages are displayed below:
> >>
> >> INFO: task btrfs-submit-0:4220 blocked for more than 120 seconds.
> >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this m=
essage.
> >> btrfs-submit- D 000000010042e12f =A0 =A0 0 =A04220 =A0 =A0 =A02 0x=
00000000
> >> =A0 ffff8803e584ac70 0000000000000046 0000000000004000 00000000000=
11680
> >> =A0 ffff8803f7349fd8 ffff8803f7349fd8 ffff8803e584ac70 00000000000=
11680
> >> =A0 0000000000000001 ffff8803ff99d250 ffffffff8149f020 00000000811=
50ab0
> >> Call Trace:
> >> =A0 [<ffffffff813089f3>] ? io_schedule+0x71/0xb1
> >> =A0 [<ffffffff811470be>] ? get_request_wait+0xab/0x140
> >> =A0 [<ffffffff810406f4>] ? autoremove_wake_function+0x0/0x2e
> >> =A0 [<ffffffff81143a4d>] ? elv_rq_merge_ok+0x89/0x97
> >> =A0 [<ffffffff8114a245>] ? blk_recount_segments+0x17/0x27
> >> =A0 [<ffffffff81147429>] ? __make_request+0x2d6/0x3fc
> >> =A0 [<ffffffff81145b16>] ? generic_make_request+0x207/0x268
> >> =A0 [<ffffffff81145c12>] ? submit_bio+0x9b/0xa2
> >> =A0 [<ffffffffa01aa081>] ? btrfs_requeue_work+0xd7/0xe1 [btrfs]
> >> =A0 [<ffffffffa01a5365>] ? run_scheduled_bios+0x297/0x48f [btrfs]
> >> =A0 [<ffffffffa01aa687>] ? worker_loop+0x17c/0x452 [btrfs]
> >> =A0 [<ffffffffa01aa50b>] ? worker_loop+0x0/0x452 [btrfs]
> >> =A0 [<ffffffff81040331>] ? kthread+0x79/0x81
> >> =A0 [<ffffffff81003674>] ? kernel_thread_helper+0x4/0x10
> >> =A0 [<ffffffff810402b8>] ? kthread+0x0/0x81
> >> =A0 [<ffffffff81003670>] ? kernel_thread_helper+0x0/0x10
> > This looks like the issue we saw too, http://lkml.org/lkml/2010/6/8=
/375.
> > This is reproduceable in our setup.
>=20
> I think I know the cause of http://lkml.org/lkml/2010/6/8/375.
> The code in the first do-while loop in btrfs_commit_transaction
> set current process to TASK_UNINTERRUPTIBLE state, then calls
> btrfs_start_delalloc_inodes, btrfs_wait_ordered_extents and
> btrfs_run_ordered_operations(). All of these function may call
> cond_resched().
The TASK_UNINTERRUPTIBLE problem was fixed with 2.6.35-rc1. You can
find the changes in the master branch of the btrfs-unstable repo.
-chris
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* Re: btrfs: hanging processes - race condition?
2010-06-13 6:50 ` Shaohua Li
@ 2010-06-14 13:28 ` Chris Mason
2010-06-14 18:12 ` Jerome Ibanes
2010-06-17 1:41 ` Shaohua Li
0 siblings, 2 replies; 12+ messages in thread
From: Chris Mason @ 2010-06-14 13:28 UTC (permalink / raw)
To: Shaohua Li
Cc: Yan, Zheng , Jerome Ibanes, linux-btrfs, Zhang, Yanmin, Chen, Tim C
On Sun, Jun 13, 2010 at 02:50:06PM +0800, Shaohua Li wrote:
> On Fri, Jun 11, 2010 at 10:32:07AM +0800, Yan, Zheng wrote:
> > On Fri, Jun 11, 2010 at 9:12 AM, Shaohua Li <shaohua.li@intel.com> =
wrote:
> > > On Fri, Jun 11, 2010 at 01:41:41AM +0800, Jerome Ibanes wrote:
> > >> List,
> > >>
> > >> I ran into a hang issue (race condition: cpu is high when the se=
rver is
> > >> idle, meaning that btrfs is hanging, and IOwait is high as well)=
running
> > >> 2.6.34 on debian/lenny on a x86_64 server (dual Opteron 275 w/ 1=
6GB ram).
> > >> The btrfs filesystem live on 18x300GB scsi spindles, configured =
as Raid-0,
> > >> as shown below:
> > >>
> > >> Label: none =A0uuid: bc6442c6-2fe2-4236-a5aa-6b7841234c52
> > >> =A0 =A0 =A0 =A0 =A0Total devices 18 FS bytes used 2.94TB
> > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A05 size 279.39GB used 208.33GB pa=
th /dev/cciss/c1d0
> > >> =A0 =A0 =A0 =A0 =A0devid =A0 17 size 279.39GB used 208.34GB path=
/dev/cciss/c1d8
> > >> =A0 =A0 =A0 =A0 =A0devid =A0 16 size 279.39GB used 209.33GB path=
/dev/cciss/c1d7
> > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A04 size 279.39GB used 208.33GB pa=
th /dev/cciss/c0d4
> > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A01 size 279.39GB used 233.72GB pa=
th /dev/cciss/c0d1
> > >> =A0 =A0 =A0 =A0 =A0devid =A0 13 size 279.39GB used 208.33GB path=
/dev/cciss/c1d4
> > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A08 size 279.39GB used 208.33GB pa=
th /dev/cciss/c1d11
> > >> =A0 =A0 =A0 =A0 =A0devid =A0 12 size 279.39GB used 208.33GB path=
/dev/cciss/c1d3
> > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A03 size 279.39GB used 208.33GB pa=
th /dev/cciss/c0d3
> > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A09 size 279.39GB used 208.33GB pa=
th /dev/cciss/c1d12
> > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A06 size 279.39GB used 208.33GB pa=
th /dev/cciss/c1d1
> > >> =A0 =A0 =A0 =A0 =A0devid =A0 11 size 279.39GB used 208.33GB path=
/dev/cciss/c1d2
> > >> =A0 =A0 =A0 =A0 =A0devid =A0 14 size 279.39GB used 208.33GB path=
/dev/cciss/c1d5
> > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A02 size 279.39GB used 233.70GB pa=
th /dev/cciss/c0d2
> > >> =A0 =A0 =A0 =A0 =A0devid =A0 15 size 279.39GB used 209.33GB path=
/dev/cciss/c1d6
> > >> =A0 =A0 =A0 =A0 =A0devid =A0 10 size 279.39GB used 208.33GB path=
/dev/cciss/c1d13
> > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A07 size 279.39GB used 208.33GB pa=
th /dev/cciss/c1d10
> > >> =A0 =A0 =A0 =A0 =A0devid =A0 18 size 279.39GB used 208.34GB path=
/dev/cciss/c1d9
> > >> Btrfs v0.19-16-g075587c-dirty
> > >>
> > >> The filesystem, mounted in /mnt/btrfs is hanging, no existing or=
new
> > >> process can access it, however 'df' still displays the disk usag=
e (3TB out
> > >> of 5). The disks appear to be physically healthy. Please note th=
at a
> > >> significant number of files were placed on this filesystem, betw=
een 20 and
> > >> 30 million files.
> > >>
> > >> The relevant kernel messages are displayed below:
> > >>
> > >> INFO: task btrfs-submit-0:4220 blocked for more than 120 seconds=
=2E
> > >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this=
message.
> > >> btrfs-submit- D 000000010042e12f =A0 =A0 0 =A04220 =A0 =A0 =A02 =
0x00000000
> > >> =A0 ffff8803e584ac70 0000000000000046 0000000000004000 000000000=
0011680
> > >> =A0 ffff8803f7349fd8 ffff8803f7349fd8 ffff8803e584ac70 000000000=
0011680
> > >> =A0 0000000000000001 ffff8803ff99d250 ffffffff8149f020 000000008=
1150ab0
> > >> Call Trace:
> > >> =A0 [<ffffffff813089f3>] ? io_schedule+0x71/0xb1
> > >> =A0 [<ffffffff811470be>] ? get_request_wait+0xab/0x140
> > >> =A0 [<ffffffff810406f4>] ? autoremove_wake_function+0x0/0x2e
> > >> =A0 [<ffffffff81143a4d>] ? elv_rq_merge_ok+0x89/0x97
> > >> =A0 [<ffffffff8114a245>] ? blk_recount_segments+0x17/0x27
> > >> =A0 [<ffffffff81147429>] ? __make_request+0x2d6/0x3fc
> > >> =A0 [<ffffffff81145b16>] ? generic_make_request+0x207/0x268
> > >> =A0 [<ffffffff81145c12>] ? submit_bio+0x9b/0xa2
> > >> =A0 [<ffffffffa01aa081>] ? btrfs_requeue_work+0xd7/0xe1 [btrfs]
> > >> =A0 [<ffffffffa01a5365>] ? run_scheduled_bios+0x297/0x48f [btrfs=
]
> > >> =A0 [<ffffffffa01aa687>] ? worker_loop+0x17c/0x452 [btrfs]
> > >> =A0 [<ffffffffa01aa50b>] ? worker_loop+0x0/0x452 [btrfs]
> > >> =A0 [<ffffffff81040331>] ? kthread+0x79/0x81
> > >> =A0 [<ffffffff81003674>] ? kernel_thread_helper+0x4/0x10
> > >> =A0 [<ffffffff810402b8>] ? kthread+0x0/0x81
> > >> =A0 [<ffffffff81003670>] ? kernel_thread_helper+0x0/0x10
> > > This looks like the issue we saw too, http://lkml.org/lkml/2010/6=
/8/375.
> > > This is reproduceable in our setup.
> >=20
> > I think I know the cause of http://lkml.org/lkml/2010/6/8/375.
> > The code in the first do-while loop in btrfs_commit_transaction
> > set current process to TASK_UNINTERRUPTIBLE state, then calls
> > btrfs_start_delalloc_inodes, btrfs_wait_ordered_extents and
> > btrfs_run_ordered_operations(). All of these function may call
> > cond_resched().
> Hi,
> When I test random write, I saw a lot of threads jump into btree_writ=
epages()
> and do noting and io throughput is zero for some time. Looks like the=
re is a
> live lock. See the code of btree_writepages():
> if (wbc->sync_mode =3D=3D WB_SYNC_NONE) {
> struct btrfs_root *root =3D BTRFS_I(mapping->host)->root;
> u64 num_dirty;
> unsigned long thresh =3D 32 * 1024 * 1024;
>=20
> if (wbc->for_kupdate)
> return 0;
>=20
> /* this is a bit racy, but that's ok */
> num_dirty =3D root->fs_info->dirty_metadata_bytes;
> >>>>>> if (num_dirty < thresh)
> return 0;
> }
> The marked line is quite intrusive. In my test, the live lock is caus=
ed by the thresh
> check. The dirty_metadata_bytes < 32M. Without it, I can't see the li=
ve lock. Not
> sure if this is related to the hang.
How much ram do you have? The goal of the check is to avoid writing
metadata blocks because once we write them we have to do more IO to cow
them again if they are changed later.
It shouldn't be looping hard in btrfs there, what was the workload?
-chris
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^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: btrfs: hanging processes - race condition?
2010-06-14 13:28 ` Chris Mason
@ 2010-06-14 18:12 ` Jerome Ibanes
2010-06-14 19:08 ` Chris Mason
2010-06-17 1:41 ` Shaohua Li
1 sibling, 1 reply; 12+ messages in thread
From: Jerome Ibanes @ 2010-06-14 18:12 UTC (permalink / raw)
To: Chris Mason
Cc: Shaohua Li, Yan, Zheng ,
Jerome Ibanes, linux-btrfs, Zhang, Yanmin, Chen, Tim C
[-- Attachment #1: Type: TEXT/PLAIN, Size: 6012 bytes --]
On Mon, 14 Jun 2010, Chris Mason wrote:
> On Sun, Jun 13, 2010 at 02:50:06PM +0800, Shaohua Li wrote:
>> On Fri, Jun 11, 2010 at 10:32:07AM +0800, Yan, Zheng wrote:
>>> On Fri, Jun 11, 2010 at 9:12 AM, Shaohua Li <shaohua.li@intel.com> wrote:
>>>> On Fri, Jun 11, 2010 at 01:41:41AM +0800, Jerome Ibanes wrote:
>>>>> List,
>>>>>
>>>>> I ran into a hang issue (race condition: cpu is high when the server is
>>>>> idle, meaning that btrfs is hanging, and IOwait is high as well) running
>>>>> 2.6.34 on debian/lenny on a x86_64 server (dual Opteron 275 w/ 16GB ram).
>>>>> The btrfs filesystem live on 18x300GB scsi spindles, configured as Raid-0,
>>>>> as shown below:
>>>>>
>>>>> Label: none uuid: bc6442c6-2fe2-4236-a5aa-6b7841234c52
>>>>> Total devices 18 FS bytes used 2.94TB
>>>>> devid 5 size 279.39GB used 208.33GB path /dev/cciss/c1d0
>>>>> devid 17 size 279.39GB used 208.34GB path /dev/cciss/c1d8
>>>>> devid 16 size 279.39GB used 209.33GB path /dev/cciss/c1d7
>>>>> devid 4 size 279.39GB used 208.33GB path /dev/cciss/c0d4
>>>>> devid 1 size 279.39GB used 233.72GB path /dev/cciss/c0d1
>>>>> devid 13 size 279.39GB used 208.33GB path /dev/cciss/c1d4
>>>>> devid 8 size 279.39GB used 208.33GB path /dev/cciss/c1d11
>>>>> devid 12 size 279.39GB used 208.33GB path /dev/cciss/c1d3
>>>>> devid 3 size 279.39GB used 208.33GB path /dev/cciss/c0d3
>>>>> devid 9 size 279.39GB used 208.33GB path /dev/cciss/c1d12
>>>>> devid 6 size 279.39GB used 208.33GB path /dev/cciss/c1d1
>>>>> devid 11 size 279.39GB used 208.33GB path /dev/cciss/c1d2
>>>>> devid 14 size 279.39GB used 208.33GB path /dev/cciss/c1d5
>>>>> devid 2 size 279.39GB used 233.70GB path /dev/cciss/c0d2
>>>>> devid 15 size 279.39GB used 209.33GB path /dev/cciss/c1d6
>>>>> devid 10 size 279.39GB used 208.33GB path /dev/cciss/c1d13
>>>>> devid 7 size 279.39GB used 208.33GB path /dev/cciss/c1d10
>>>>> devid 18 size 279.39GB used 208.34GB path /dev/cciss/c1d9
>>>>> Btrfs v0.19-16-g075587c-dirty
>>>>>
>>>>> The filesystem, mounted in /mnt/btrfs is hanging, no existing or new
>>>>> process can access it, however 'df' still displays the disk usage (3TB out
>>>>> of 5). The disks appear to be physically healthy. Please note that a
>>>>> significant number of files were placed on this filesystem, between 20 and
>>>>> 30 million files.
>>>>>
>>>>> The relevant kernel messages are displayed below:
>>>>>
>>>>> INFO: task btrfs-submit-0:4220 blocked for more than 120 seconds.
>>>>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>>>>> btrfs-submit- D 000000010042e12f 0 4220 2 0x00000000
>>>>> ffff8803e584ac70 0000000000000046 0000000000004000 0000000000011680
>>>>> ffff8803f7349fd8 ffff8803f7349fd8 ffff8803e584ac70 0000000000011680
>>>>> 0000000000000001 ffff8803ff99d250 ffffffff8149f020 0000000081150ab0
>>>>> Call Trace:
>>>>> [<ffffffff813089f3>] ? io_schedule+0x71/0xb1
>>>>> [<ffffffff811470be>] ? get_request_wait+0xab/0x140
>>>>> [<ffffffff810406f4>] ? autoremove_wake_function+0x0/0x2e
>>>>> [<ffffffff81143a4d>] ? elv_rq_merge_ok+0x89/0x97
>>>>> [<ffffffff8114a245>] ? blk_recount_segments+0x17/0x27
>>>>> [<ffffffff81147429>] ? __make_request+0x2d6/0x3fc
>>>>> [<ffffffff81145b16>] ? generic_make_request+0x207/0x268
>>>>> [<ffffffff81145c12>] ? submit_bio+0x9b/0xa2
>>>>> [<ffffffffa01aa081>] ? btrfs_requeue_work+0xd7/0xe1 [btrfs]
>>>>> [<ffffffffa01a5365>] ? run_scheduled_bios+0x297/0x48f [btrfs]
>>>>> [<ffffffffa01aa687>] ? worker_loop+0x17c/0x452 [btrfs]
>>>>> [<ffffffffa01aa50b>] ? worker_loop+0x0/0x452 [btrfs]
>>>>> [<ffffffff81040331>] ? kthread+0x79/0x81
>>>>> [<ffffffff81003674>] ? kernel_thread_helper+0x4/0x10
>>>>> [<ffffffff810402b8>] ? kthread+0x0/0x81
>>>>> [<ffffffff81003670>] ? kernel_thread_helper+0x0/0x10
>>>> This looks like the issue we saw too, http://lkml.org/lkml/2010/6/8/375.
>>>> This is reproduceable in our setup.
>>>
>>> I think I know the cause of http://lkml.org/lkml/2010/6/8/375.
>>> The code in the first do-while loop in btrfs_commit_transaction
>>> set current process to TASK_UNINTERRUPTIBLE state, then calls
>>> btrfs_start_delalloc_inodes, btrfs_wait_ordered_extents and
>>> btrfs_run_ordered_operations(). All of these function may call
>>> cond_resched().
>> Hi,
>> When I test random write, I saw a lot of threads jump into btree_writepages()
>> and do noting and io throughput is zero for some time. Looks like there is a
>> live lock. See the code of btree_writepages():
>> if (wbc->sync_mode == WB_SYNC_NONE) {
>> struct btrfs_root *root = BTRFS_I(mapping->host)->root;
>> u64 num_dirty;
>> unsigned long thresh = 32 * 1024 * 1024;
>>
>> if (wbc->for_kupdate)
>> return 0;
>>
>> /* this is a bit racy, but that's ok */
>> num_dirty = root->fs_info->dirty_metadata_bytes;
>>>>>>>> if (num_dirty < thresh)
>> return 0;
>> }
>> The marked line is quite intrusive. In my test, the live lock is caused by the thresh
>> check. The dirty_metadata_bytes < 32M. Without it, I can't see the live lock. Not
>> sure if this is related to the hang.
>
> How much ram do you have? The goal of the check is to avoid writing
> metadata blocks because once we write them we have to do more IO to cow
> them again if they are changed later.
This server has 16GB of ram on a x86_64 (dual opteron 275, ecc memory).
> It shouldn't be looping hard in btrfs there, what was the workload?
The workload was the extraction of large tarballs (one at the time, about
300+ files extracted by second from a single tarball, which is pretty
good), as you might expect, the disks were tested (read and write) for
physical errors before I report this bug.
Jerome J. Ibanes
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: btrfs: hanging processes - race condition?
2010-06-14 18:12 ` Jerome Ibanes
@ 2010-06-14 19:08 ` Chris Mason
2010-06-14 19:13 ` Jerome Ibanes
0 siblings, 1 reply; 12+ messages in thread
From: Chris Mason @ 2010-06-14 19:08 UTC (permalink / raw)
To: Jerome Ibanes
Cc: Shaohua Li, Yan, Zheng , linux-btrfs, Zhang, Yanmin, Chen, Tim C
On Mon, Jun 14, 2010 at 11:12:53AM -0700, Jerome Ibanes wrote:
> On Mon, 14 Jun 2010, Chris Mason wrote:
>=20
> >On Sun, Jun 13, 2010 at 02:50:06PM +0800, Shaohua Li wrote:
> >>On Fri, Jun 11, 2010 at 10:32:07AM +0800, Yan, Zheng wrote:
> >>>On Fri, Jun 11, 2010 at 9:12 AM, Shaohua Li <shaohua.li@intel.com>=
wrote:
> >>>>On Fri, Jun 11, 2010 at 01:41:41AM +0800, Jerome Ibanes wrote:
> >>>>>List,
> >>>>>
> >>>>>I ran into a hang issue (race condition: cpu is high when the se=
rver is
> >>>>>idle, meaning that btrfs is hanging, and IOwait is high as well)=
running
> >>>>>2.6.34 on debian/lenny on a x86_64 server (dual Opteron 275 w/ 1=
6GB ram).
> >>>>>The btrfs filesystem live on 18x300GB scsi spindles, configured =
as Raid-0,
> >>>>>as shown below:
> >>>>>
> >>>>>Label: none =A0uuid: bc6442c6-2fe2-4236-a5aa-6b7841234c52
> >>>>>=A0 =A0 =A0 =A0 =A0Total devices 18 FS bytes used 2.94TB
> >>>>>=A0 =A0 =A0 =A0 =A0devid =A0 =A05 size 279.39GB used 208.33GB pa=
th /dev/cciss/c1d0
> >>>>>=A0 =A0 =A0 =A0 =A0devid =A0 17 size 279.39GB used 208.34GB path=
/dev/cciss/c1d8
> >>>>>=A0 =A0 =A0 =A0 =A0devid =A0 16 size 279.39GB used 209.33GB path=
/dev/cciss/c1d7
> >>>>>=A0 =A0 =A0 =A0 =A0devid =A0 =A04 size 279.39GB used 208.33GB pa=
th /dev/cciss/c0d4
> >>>>>=A0 =A0 =A0 =A0 =A0devid =A0 =A01 size 279.39GB used 233.72GB pa=
th /dev/cciss/c0d1
> >>>>>=A0 =A0 =A0 =A0 =A0devid =A0 13 size 279.39GB used 208.33GB path=
/dev/cciss/c1d4
> >>>>>=A0 =A0 =A0 =A0 =A0devid =A0 =A08 size 279.39GB used 208.33GB pa=
th /dev/cciss/c1d11
> >>>>>=A0 =A0 =A0 =A0 =A0devid =A0 12 size 279.39GB used 208.33GB path=
/dev/cciss/c1d3
> >>>>>=A0 =A0 =A0 =A0 =A0devid =A0 =A03 size 279.39GB used 208.33GB pa=
th /dev/cciss/c0d3
> >>>>>=A0 =A0 =A0 =A0 =A0devid =A0 =A09 size 279.39GB used 208.33GB pa=
th /dev/cciss/c1d12
> >>>>>=A0 =A0 =A0 =A0 =A0devid =A0 =A06 size 279.39GB used 208.33GB pa=
th /dev/cciss/c1d1
> >>>>>=A0 =A0 =A0 =A0 =A0devid =A0 11 size 279.39GB used 208.33GB path=
/dev/cciss/c1d2
> >>>>>=A0 =A0 =A0 =A0 =A0devid =A0 14 size 279.39GB used 208.33GB path=
/dev/cciss/c1d5
> >>>>>=A0 =A0 =A0 =A0 =A0devid =A0 =A02 size 279.39GB used 233.70GB pa=
th /dev/cciss/c0d2
> >>>>>=A0 =A0 =A0 =A0 =A0devid =A0 15 size 279.39GB used 209.33GB path=
/dev/cciss/c1d6
> >>>>>=A0 =A0 =A0 =A0 =A0devid =A0 10 size 279.39GB used 208.33GB path=
/dev/cciss/c1d13
> >>>>>=A0 =A0 =A0 =A0 =A0devid =A0 =A07 size 279.39GB used 208.33GB pa=
th /dev/cciss/c1d10
> >>>>>=A0 =A0 =A0 =A0 =A0devid =A0 18 size 279.39GB used 208.34GB path=
/dev/cciss/c1d9
> >>>>>Btrfs v0.19-16-g075587c-dirty
> >>>>>
> >>>>>The filesystem, mounted in /mnt/btrfs is hanging, no existing or=
new
> >>>>>process can access it, however 'df' still displays the disk usag=
e (3TB out
> >>>>>of 5). The disks appear to be physically healthy. Please note th=
at a
> >>>>>significant number of files were placed on this filesystem, betw=
een 20 and
> >>>>>30 million files.
> >>>>>
> >>>>>The relevant kernel messages are displayed below:
> >>>>>
> >>>>>INFO: task btrfs-submit-0:4220 blocked for more than 120 seconds=
=2E
> >>>>>"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this=
message.
> >>>>>btrfs-submit- D 000000010042e12f =A0 =A0 0 =A04220 =A0 =A0 =A02 =
0x00000000
> >>>>>=A0 ffff8803e584ac70 0000000000000046 0000000000004000 000000000=
0011680
> >>>>>=A0 ffff8803f7349fd8 ffff8803f7349fd8 ffff8803e584ac70 000000000=
0011680
> >>>>>=A0 0000000000000001 ffff8803ff99d250 ffffffff8149f020 000000008=
1150ab0
> >>>>>Call Trace:
> >>>>>=A0 [<ffffffff813089f3>] ? io_schedule+0x71/0xb1
> >>>>>=A0 [<ffffffff811470be>] ? get_request_wait+0xab/0x140
> >>>>>=A0 [<ffffffff810406f4>] ? autoremove_wake_function+0x0/0x2e
> >>>>>=A0 [<ffffffff81143a4d>] ? elv_rq_merge_ok+0x89/0x97
> >>>>>=A0 [<ffffffff8114a245>] ? blk_recount_segments+0x17/0x27
> >>>>>=A0 [<ffffffff81147429>] ? __make_request+0x2d6/0x3fc
> >>>>>=A0 [<ffffffff81145b16>] ? generic_make_request+0x207/0x268
> >>>>>=A0 [<ffffffff81145c12>] ? submit_bio+0x9b/0xa2
> >>>>>=A0 [<ffffffffa01aa081>] ? btrfs_requeue_work+0xd7/0xe1 [btrfs]
> >>>>>=A0 [<ffffffffa01a5365>] ? run_scheduled_bios+0x297/0x48f [btrfs=
]
> >>>>>=A0 [<ffffffffa01aa687>] ? worker_loop+0x17c/0x452 [btrfs]
> >>>>>=A0 [<ffffffffa01aa50b>] ? worker_loop+0x0/0x452 [btrfs]
> >>>>>=A0 [<ffffffff81040331>] ? kthread+0x79/0x81
> >>>>>=A0 [<ffffffff81003674>] ? kernel_thread_helper+0x4/0x10
> >>>>>=A0 [<ffffffff810402b8>] ? kthread+0x0/0x81
> >>>>>=A0 [<ffffffff81003670>] ? kernel_thread_helper+0x0/0x10
> >>>>This looks like the issue we saw too, http://lkml.org/lkml/2010/6=
/8/375.
> >>>>This is reproduceable in our setup.
> >>>
> >>>I think I know the cause of http://lkml.org/lkml/2010/6/8/375.
> >>>The code in the first do-while loop in btrfs_commit_transaction
> >>>set current process to TASK_UNINTERRUPTIBLE state, then calls
> >>>btrfs_start_delalloc_inodes, btrfs_wait_ordered_extents and
> >>>btrfs_run_ordered_operations(). All of these function may call
> >>>cond_resched().
> >>Hi,
> >>When I test random write, I saw a lot of threads jump into btree_wr=
itepages()
> >>and do noting and io throughput is zero for some time. Looks like t=
here is a
> >>live lock. See the code of btree_writepages():
> >> if (wbc->sync_mode =3D=3D WB_SYNC_NONE) {
> >> struct btrfs_root *root =3D BTRFS_I(mapping->host)->root;
> >> u64 num_dirty;
> >> unsigned long thresh =3D 32 * 1024 * 1024;
> >>
> >> if (wbc->for_kupdate)
> >> return 0;
> >>
> >> /* this is a bit racy, but that's ok */
> >> num_dirty =3D root->fs_info->dirty_metadata_bytes;
> >>>>>>>> if (num_dirty < thresh)
> >> return 0;
> >> }
> >>The marked line is quite intrusive. In my test, the live lock is ca=
used by the thresh
> >>check. The dirty_metadata_bytes < 32M. Without it, I can't see the =
live lock. Not
> >>sure if this is related to the hang.
> >
> >How much ram do you have? The goal of the check is to avoid writing
> >metadata blocks because once we write them we have to do more IO to =
cow
> >them again if they are changed later.
>=20
> This server has 16GB of ram on a x86_64 (dual opteron 275, ecc memory=
).
>=20
> >It shouldn't be looping hard in btrfs there, what was the workload?
>=20
> The workload was the extraction of large tarballs (one at the time,
> about 300+ files extracted by second from a single tarball, which is
> pretty good), as you might expect, the disks were tested (read and
> write) for physical errors before I report this bug.
I think Zheng is right and this one will get fixed by the latest code.
The spinning writepage part should be a different problem.
-chris
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^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: btrfs: hanging processes - race condition?
2010-06-14 19:08 ` Chris Mason
@ 2010-06-14 19:13 ` Jerome Ibanes
2010-06-16 18:12 ` Jerome Ibanes
0 siblings, 1 reply; 12+ messages in thread
From: Jerome Ibanes @ 2010-06-14 19:13 UTC (permalink / raw)
To: Chris Mason
Cc: Shaohua Li, Yan, Zheng , linux-btrfs, Zhang, Yanmin, Chen, Tim C
[-- Attachment #1: Type: TEXT/PLAIN, Size: 6510 bytes --]
> On Mon, Jun 14, 2010 at 11:12:53AM -0700, Jerome Ibanes wrote:
>> On Mon, 14 Jun 2010, Chris Mason wrote:
>>
>>> On Sun, Jun 13, 2010 at 02:50:06PM +0800, Shaohua Li wrote:
>>>> On Fri, Jun 11, 2010 at 10:32:07AM +0800, Yan, Zheng wrote:
>>>>> On Fri, Jun 11, 2010 at 9:12 AM, Shaohua Li <shaohua.li@intel.com> wrote:
>>>>>> On Fri, Jun 11, 2010 at 01:41:41AM +0800, Jerome Ibanes wrote:
>>>>>>> List,
>>>>>>>
>>>>>>> I ran into a hang issue (race condition: cpu is high when the server is
>>>>>>> idle, meaning that btrfs is hanging, and IOwait is high as well) running
>>>>>>> 2.6.34 on debian/lenny on a x86_64 server (dual Opteron 275 w/ 16GB ram).
>>>>>>> The btrfs filesystem live on 18x300GB scsi spindles, configured as Raid-0,
>>>>>>> as shown below:
>>>>>>>
>>>>>>> Label: none uuid: bc6442c6-2fe2-4236-a5aa-6b7841234c52
>>>>>>> Total devices 18 FS bytes used 2.94TB
>>>>>>> devid 5 size 279.39GB used 208.33GB path /dev/cciss/c1d0
>>>>>>> devid 17 size 279.39GB used 208.34GB path /dev/cciss/c1d8
>>>>>>> devid 16 size 279.39GB used 209.33GB path /dev/cciss/c1d7
>>>>>>> devid 4 size 279.39GB used 208.33GB path /dev/cciss/c0d4
>>>>>>> devid 1 size 279.39GB used 233.72GB path /dev/cciss/c0d1
>>>>>>> devid 13 size 279.39GB used 208.33GB path /dev/cciss/c1d4
>>>>>>> devid 8 size 279.39GB used 208.33GB path /dev/cciss/c1d11
>>>>>>> devid 12 size 279.39GB used 208.33GB path /dev/cciss/c1d3
>>>>>>> devid 3 size 279.39GB used 208.33GB path /dev/cciss/c0d3
>>>>>>> devid 9 size 279.39GB used 208.33GB path /dev/cciss/c1d12
>>>>>>> devid 6 size 279.39GB used 208.33GB path /dev/cciss/c1d1
>>>>>>> devid 11 size 279.39GB used 208.33GB path /dev/cciss/c1d2
>>>>>>> devid 14 size 279.39GB used 208.33GB path /dev/cciss/c1d5
>>>>>>> devid 2 size 279.39GB used 233.70GB path /dev/cciss/c0d2
>>>>>>> devid 15 size 279.39GB used 209.33GB path /dev/cciss/c1d6
>>>>>>> devid 10 size 279.39GB used 208.33GB path /dev/cciss/c1d13
>>>>>>> devid 7 size 279.39GB used 208.33GB path /dev/cciss/c1d10
>>>>>>> devid 18 size 279.39GB used 208.34GB path /dev/cciss/c1d9
>>>>>>> Btrfs v0.19-16-g075587c-dirty
>>>>>>>
>>>>>>> The filesystem, mounted in /mnt/btrfs is hanging, no existing or new
>>>>>>> process can access it, however 'df' still displays the disk usage (3TB out
>>>>>>> of 5). The disks appear to be physically healthy. Please note that a
>>>>>>> significant number of files were placed on this filesystem, between 20 and
>>>>>>> 30 million files.
>>>>>>>
>>>>>>> The relevant kernel messages are displayed below:
>>>>>>>
>>>>>>> INFO: task btrfs-submit-0:4220 blocked for more than 120 seconds.
>>>>>>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>>>>>>> btrfs-submit- D 000000010042e12f 0 4220 2 0x00000000
>>>>>>> ffff8803e584ac70 0000000000000046 0000000000004000 0000000000011680
>>>>>>> ffff8803f7349fd8 ffff8803f7349fd8 ffff8803e584ac70 0000000000011680
>>>>>>> 0000000000000001 ffff8803ff99d250 ffffffff8149f020 0000000081150ab0
>>>>>>> Call Trace:
>>>>>>> [<ffffffff813089f3>] ? io_schedule+0x71/0xb1
>>>>>>> [<ffffffff811470be>] ? get_request_wait+0xab/0x140
>>>>>>> [<ffffffff810406f4>] ? autoremove_wake_function+0x0/0x2e
>>>>>>> [<ffffffff81143a4d>] ? elv_rq_merge_ok+0x89/0x97
>>>>>>> [<ffffffff8114a245>] ? blk_recount_segments+0x17/0x27
>>>>>>> [<ffffffff81147429>] ? __make_request+0x2d6/0x3fc
>>>>>>> [<ffffffff81145b16>] ? generic_make_request+0x207/0x268
>>>>>>> [<ffffffff81145c12>] ? submit_bio+0x9b/0xa2
>>>>>>> [<ffffffffa01aa081>] ? btrfs_requeue_work+0xd7/0xe1 [btrfs]
>>>>>>> [<ffffffffa01a5365>] ? run_scheduled_bios+0x297/0x48f [btrfs]
>>>>>>> [<ffffffffa01aa687>] ? worker_loop+0x17c/0x452 [btrfs]
>>>>>>> [<ffffffffa01aa50b>] ? worker_loop+0x0/0x452 [btrfs]
>>>>>>> [<ffffffff81040331>] ? kthread+0x79/0x81
>>>>>>> [<ffffffff81003674>] ? kernel_thread_helper+0x4/0x10
>>>>>>> [<ffffffff810402b8>] ? kthread+0x0/0x81
>>>>>>> [<ffffffff81003670>] ? kernel_thread_helper+0x0/0x10
>>>>>> This looks like the issue we saw too, http://lkml.org/lkml/2010/6/8/375.
>>>>>> This is reproduceable in our setup.
>>>>>
>>>>> I think I know the cause of http://lkml.org/lkml/2010/6/8/375.
>>>>> The code in the first do-while loop in btrfs_commit_transaction
>>>>> set current process to TASK_UNINTERRUPTIBLE state, then calls
>>>>> btrfs_start_delalloc_inodes, btrfs_wait_ordered_extents and
>>>>> btrfs_run_ordered_operations(). All of these function may call
>>>>> cond_resched().
>>>> Hi,
>>>> When I test random write, I saw a lot of threads jump into btree_writepages()
>>>> and do noting and io throughput is zero for some time. Looks like there is a
>>>> live lock. See the code of btree_writepages():
>>>> if (wbc->sync_mode == WB_SYNC_NONE) {
>>>> struct btrfs_root *root = BTRFS_I(mapping->host)->root;
>>>> u64 num_dirty;
>>>> unsigned long thresh = 32 * 1024 * 1024;
>>>>
>>>> if (wbc->for_kupdate)
>>>> return 0;
>>>>
>>>> /* this is a bit racy, but that's ok */
>>>> num_dirty = root->fs_info->dirty_metadata_bytes;
>>>>>>>>>> if (num_dirty < thresh)
>>>> return 0;
>>>> }
>>>> The marked line is quite intrusive. In my test, the live lock is caused by the thresh
>>>> check. The dirty_metadata_bytes < 32M. Without it, I can't see the live lock. Not
>>>> sure if this is related to the hang.
>>>
>>> How much ram do you have? The goal of the check is to avoid writing
>>> metadata blocks because once we write them we have to do more IO to cow
>>> them again if they are changed later.
>>
>> This server has 16GB of ram on a x86_64 (dual opteron 275, ecc memory).
>>
>>> It shouldn't be looping hard in btrfs there, what was the workload?
>>
>> The workload was the extraction of large tarballs (one at the time,
>> about 300+ files extracted by second from a single tarball, which is
>> pretty good), as you might expect, the disks were tested (read and
>> write) for physical errors before I report this bug.
>
> I think Zheng is right and this one will get fixed by the latest code.
> The spinning writepage part should be a different problem.
I'm trying to repro with 2.6.35-rc3, expect results within 24 hours.
Jerome J. Ibanes
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: btrfs: hanging processes - race condition?
2010-06-14 19:13 ` Jerome Ibanes
@ 2010-06-16 18:12 ` Jerome Ibanes
0 siblings, 0 replies; 12+ messages in thread
From: Jerome Ibanes @ 2010-06-16 18:12 UTC (permalink / raw)
To: chris.mason, shaohua.li, yanzheng, linux-btrfs, yanmin.zhang, tim.c.chen
Cc: Nicolas Michal
[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: TEXT/PLAIN; charset=X-UNKNOWN; format=flowed, Size: 8536 bytes --]
On Mon, 14 Jun 2010, Jerome Ibanes wrote:
>> On Mon, Jun 14, 2010 at 11:12:53AM -0700, Jerome Ibanes wrote:
>> > On Mon, 14 Jun 2010, Chris Mason wrote:
>> >
>> > > On Sun, Jun 13, 2010 at 02:50:06PM +0800, Shaohua Li wrote:
>> > > > On Fri, Jun 11, 2010 at 10:32:07AM +0800, Yan, Zheng wrote:
>> > > > > On Fri, Jun 11, 2010 at 9:12 AM, Shaohua Li <shaohua.li@intel.com>
>> > > > > wrote:
>> > > > > > On Fri, Jun 11, 2010 at 01:41:41AM +0800, Jerome Ibanes wrote:
>> > > > > > > List,
>> > > > > > >
>> > > > > > > I ran into a hang issue (race condition: cpu is high when the
>> > > > > > > server is
>> > > > > > > idle, meaning that btrfs is hanging, and IOwait is high as
>> > > > > > > well) running
>> > > > > > > 2.6.34 on debian/lenny on a x86_64 server (dual Opteron 275 w/
>> > > > > > > 16GB ram).
>> > > > > > > The btrfs filesystem live on 18x300GB scsi spindles,
>> > > > > > > configured as Raid-0,
>> > > > > > > as shown below:
>> > > > > > >
>> > > > > > > Label: none uuid: bc6442c6-2fe2-4236-a5aa-6b7841234c52
>> > > > > > > Total devices 18 FS bytes used 2.94TB
>> > > > > > > devid 5 size 279.39GB used 208.33GB path
>> > > > > > > /dev/cciss/c1d0
>> > > > > > > devid 17 size 279.39GB used 208.34GB path
>> > > > > > > /dev/cciss/c1d8
>> > > > > > > devid 16 size 279.39GB used 209.33GB path
>> > > > > > > /dev/cciss/c1d7
>> > > > > > > devid 4 size 279.39GB used 208.33GB path
>> > > > > > > /dev/cciss/c0d4
>> > > > > > > devid 1 size 279.39GB used 233.72GB path
>> > > > > > > /dev/cciss/c0d1
>> > > > > > > devid 13 size 279.39GB used 208.33GB path
>> > > > > > > /dev/cciss/c1d4
>> > > > > > > devid 8 size 279.39GB used 208.33GB path
>> > > > > > > /dev/cciss/c1d11
>> > > > > > > devid 12 size 279.39GB used 208.33GB path
>> > > > > > > /dev/cciss/c1d3
>> > > > > > > devid 3 size 279.39GB used 208.33GB path
>> > > > > > > /dev/cciss/c0d3
>> > > > > > > devid 9 size 279.39GB used 208.33GB path
>> > > > > > > /dev/cciss/c1d12
>> > > > > > > devid 6 size 279.39GB used 208.33GB path
>> > > > > > > /dev/cciss/c1d1
>> > > > > > > devid 11 size 279.39GB used 208.33GB path
>> > > > > > > /dev/cciss/c1d2
>> > > > > > > devid 14 size 279.39GB used 208.33GB path
>> > > > > > > /dev/cciss/c1d5
>> > > > > > > devid 2 size 279.39GB used 233.70GB path
>> > > > > > > /dev/cciss/c0d2
>> > > > > > > devid 15 size 279.39GB used 209.33GB path
>> > > > > > > /dev/cciss/c1d6
>> > > > > > > devid 10 size 279.39GB used 208.33GB path
>> > > > > > > /dev/cciss/c1d13
>> > > > > > > devid 7 size 279.39GB used 208.33GB path
>> > > > > > > /dev/cciss/c1d10
>> > > > > > > devid 18 size 279.39GB used 208.34GB path
>> > > > > > > /dev/cciss/c1d9
>> > > > > > > Btrfs v0.19-16-g075587c-dirty
>> > > > > > >
>> > > > > > > The filesystem, mounted in /mnt/btrfs is hanging, no existing
>> > > > > > > or new
>> > > > > > > process can access it, however 'df' still displays the disk
>> > > > > > > usage (3TB out
>> > > > > > > of 5). The disks appear to be physically healthy. Please note
>> > > > > > > that a
>> > > > > > > significant number of files were placed on this filesystem,
>> > > > > > > between 20 and
>> > > > > > > 30 million files.
>> > > > > > >
>> > > > > > > The relevant kernel messages are displayed below:
>> > > > > > >
>> > > > > > > INFO: task btrfs-submit-0:4220 blocked for more than 120
>> > > > > > > seconds.
>> > > > > > > "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables
>> > > > > > > this message.
>> > > > > > > btrfs-submit- D 000000010042e12f 0 4220 2 0x00000000
>> > > > > > > ffff8803e584ac70 0000000000000046 0000000000004000
>> > > > > > > 0000000000011680
>> > > > > > > ffff8803f7349fd8 ffff8803f7349fd8 ffff8803e584ac70
>> > > > > > > 0000000000011680
>> > > > > > > 0000000000000001 ffff8803ff99d250 ffffffff8149f020
>> > > > > > > 0000000081150ab0
>> > > > > > > Call Trace:
>> > > > > > > [<ffffffff813089f3>] ? io_schedule+0x71/0xb1
>> > > > > > > [<ffffffff811470be>] ? get_request_wait+0xab/0x140
>> > > > > > > [<ffffffff810406f4>] ? autoremove_wake_function+0x0/0x2e
>> > > > > > > [<ffffffff81143a4d>] ? elv_rq_merge_ok+0x89/0x97
>> > > > > > > [<ffffffff8114a245>] ? blk_recount_segments+0x17/0x27
>> > > > > > > [<ffffffff81147429>] ? __make_request+0x2d6/0x3fc
>> > > > > > > [<ffffffff81145b16>] ? generic_make_request+0x207/0x268
>> > > > > > > [<ffffffff81145c12>] ? submit_bio+0x9b/0xa2
>> > > > > > > [<ffffffffa01aa081>] ? btrfs_requeue_work+0xd7/0xe1
>> > > > > > > [btrfs]
>> > > > > > > [<ffffffffa01a5365>] ? run_scheduled_bios+0x297/0x48f
>> > > > > > > [btrfs]
>> > > > > > > [<ffffffffa01aa687>] ? worker_loop+0x17c/0x452 [btrfs]
>> > > > > > > [<ffffffffa01aa50b>] ? worker_loop+0x0/0x452 [btrfs]
>> > > > > > > [<ffffffff81040331>] ? kthread+0x79/0x81
>> > > > > > > [<ffffffff81003674>] ? kernel_thread_helper+0x4/0x10
>> > > > > > > [<ffffffff810402b8>] ? kthread+0x0/0x81
>> > > > > > > [<ffffffff81003670>] ? kernel_thread_helper+0x0/0x10
>> > > > > > This looks like the issue we saw too,
>> > > > > > http://lkml.org/lkml/2010/6/8/375.
>> > > > > > This is reproduceable in our setup.
>> > > > >
>> > > > > I think I know the cause of http://lkml.org/lkml/2010/6/8/375.
>> > > > > The code in the first do-while loop in btrfs_commit_transaction
>> > > > > set current process to TASK_UNINTERRUPTIBLE state, then calls
>> > > > > btrfs_start_delalloc_inodes, btrfs_wait_ordered_extents and
>> > > > > btrfs_run_ordered_operations(). All of these function may call
>> > > > > cond_resched().
>> > > > Hi,
>> > > > When I test random write, I saw a lot of threads jump into
>> > > > btree_writepages()
>> > > > and do noting and io throughput is zero for some time. Looks like
>> > > > there is a
>> > > > live lock. See the code of btree_writepages():
>> > > > if (wbc->sync_mode == WB_SYNC_NONE) {
>> > > > struct btrfs_root *root = BTRFS_I(mapping->host)->root;
>> > > > u64 num_dirty;
>> > > > unsigned long thresh = 32 * 1024 * 1024;
>> > > >
>> > > > if (wbc->for_kupdate)
>> > > > return 0;
>> > > >
>> > > > /* this is a bit racy, but that's ok */
>> > > > num_dirty = root->fs_info->dirty_metadata_bytes;
>> > > > > > > > > > if (num_dirty < thresh)
>> > > > return 0;
>> > > > }
>> > > > The marked line is quite intrusive. In my test, the live lock is
>> > > > caused by the thresh
>> > > > check. The dirty_metadata_bytes < 32M. Without it, I can't see the
>> > > > live lock. Not
>> > > > sure if this is related to the hang.
>> > >
>> > > How much ram do you have? The goal of the check is to avoid writing
>> > > metadata blocks because once we write them we have to do more IO to
>> > > cow
>> > > them again if they are changed later.
>> >
>> > This server has 16GB of ram on a x86_64 (dual opteron 275, ecc memory).
>> >
>> > > It shouldn't be looping hard in btrfs there, what was the workload?
>> >
>> > The workload was the extraction of large tarballs (one at the time,
>> > about 300+ files extracted by second from a single tarball, which is
>> > pretty good), as you might expect, the disks were tested (read and
>> > write) for physical errors before I report this bug.
>>
>> I think Zheng is right and this one will get fixed by the latest code.
>> The spinning writepage part should be a different problem.
>
> I'm trying to repro with 2.6.35-rc3, expect results within 24 hours.
I can no longer repro this issue (after 48 hours of filesystem stress)
under 2.6.35-rc3 on a filesystem with over 50 million files. I will reopen
this thread should this reoccur.
Jerome J. Ibanes
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: btrfs: hanging processes - race condition?
2010-06-14 13:28 ` Chris Mason
2010-06-14 18:12 ` Jerome Ibanes
@ 2010-06-17 1:41 ` Shaohua Li
2010-06-18 0:57 ` Shaohua Li
1 sibling, 1 reply; 12+ messages in thread
From: Shaohua Li @ 2010-06-17 1:41 UTC (permalink / raw)
To: Chris Mason, Yan, Zheng , Jerome Ibanes, linux-btrfs,
On Mon, Jun 14, 2010 at 09:28:29PM +0800, Chris Mason wrote:
> On Sun, Jun 13, 2010 at 02:50:06PM +0800, Shaohua Li wrote:
> > On Fri, Jun 11, 2010 at 10:32:07AM +0800, Yan, Zheng wrote:
> > > On Fri, Jun 11, 2010 at 9:12 AM, Shaohua Li <shaohua.li@intel.com=
> wrote:
> > > > On Fri, Jun 11, 2010 at 01:41:41AM +0800, Jerome Ibanes wrote:
> > > >> List,
> > > >>
> > > >> I ran into a hang issue (race condition: cpu is high when the =
server is
> > > >> idle, meaning that btrfs is hanging, and IOwait is high as wel=
l) running
> > > >> 2.6.34 on debian/lenny on a x86_64 server (dual Opteron 275 w/=
16GB ram).
> > > >> The btrfs filesystem live on 18x300GB scsi spindles, configure=
d as Raid-0,
> > > >> as shown below:
> > > >>
> > > >> Label: none =A0uuid: bc6442c6-2fe2-4236-a5aa-6b7841234c52
> > > >> =A0 =A0 =A0 =A0 =A0Total devices 18 FS bytes used 2.94TB
> > > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A05 size 279.39GB used 208.33GB =
path /dev/cciss/c1d0
> > > >> =A0 =A0 =A0 =A0 =A0devid =A0 17 size 279.39GB used 208.34GB pa=
th /dev/cciss/c1d8
> > > >> =A0 =A0 =A0 =A0 =A0devid =A0 16 size 279.39GB used 209.33GB pa=
th /dev/cciss/c1d7
> > > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A04 size 279.39GB used 208.33GB =
path /dev/cciss/c0d4
> > > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A01 size 279.39GB used 233.72GB =
path /dev/cciss/c0d1
> > > >> =A0 =A0 =A0 =A0 =A0devid =A0 13 size 279.39GB used 208.33GB pa=
th /dev/cciss/c1d4
> > > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A08 size 279.39GB used 208.33GB =
path /dev/cciss/c1d11
> > > >> =A0 =A0 =A0 =A0 =A0devid =A0 12 size 279.39GB used 208.33GB pa=
th /dev/cciss/c1d3
> > > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A03 size 279.39GB used 208.33GB =
path /dev/cciss/c0d3
> > > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A09 size 279.39GB used 208.33GB =
path /dev/cciss/c1d12
> > > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A06 size 279.39GB used 208.33GB =
path /dev/cciss/c1d1
> > > >> =A0 =A0 =A0 =A0 =A0devid =A0 11 size 279.39GB used 208.33GB pa=
th /dev/cciss/c1d2
> > > >> =A0 =A0 =A0 =A0 =A0devid =A0 14 size 279.39GB used 208.33GB pa=
th /dev/cciss/c1d5
> > > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A02 size 279.39GB used 233.70GB =
path /dev/cciss/c0d2
> > > >> =A0 =A0 =A0 =A0 =A0devid =A0 15 size 279.39GB used 209.33GB pa=
th /dev/cciss/c1d6
> > > >> =A0 =A0 =A0 =A0 =A0devid =A0 10 size 279.39GB used 208.33GB pa=
th /dev/cciss/c1d13
> > > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A07 size 279.39GB used 208.33GB =
path /dev/cciss/c1d10
> > > >> =A0 =A0 =A0 =A0 =A0devid =A0 18 size 279.39GB used 208.34GB pa=
th /dev/cciss/c1d9
> > > >> Btrfs v0.19-16-g075587c-dirty
> > > >>
> > > >> The filesystem, mounted in /mnt/btrfs is hanging, no existing =
or new
> > > >> process can access it, however 'df' still displays the disk us=
age (3TB out
> > > >> of 5). The disks appear to be physically healthy. Please note =
that a
> > > >> significant number of files were placed on this filesystem, be=
tween 20 and
> > > >> 30 million files.
> > > >>
> > > >> The relevant kernel messages are displayed below:
> > > >>
> > > >> INFO: task btrfs-submit-0:4220 blocked for more than 120 secon=
ds.
> > > >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables th=
is message.
> > > >> btrfs-submit- D 000000010042e12f =A0 =A0 0 =A04220 =A0 =A0 =A0=
2 0x00000000
> > > >> =A0 ffff8803e584ac70 0000000000000046 0000000000004000 0000000=
000011680
> > > >> =A0 ffff8803f7349fd8 ffff8803f7349fd8 ffff8803e584ac70 0000000=
000011680
> > > >> =A0 0000000000000001 ffff8803ff99d250 ffffffff8149f020 0000000=
081150ab0
> > > >> Call Trace:
> > > >> =A0 [<ffffffff813089f3>] ? io_schedule+0x71/0xb1
> > > >> =A0 [<ffffffff811470be>] ? get_request_wait+0xab/0x140
> > > >> =A0 [<ffffffff810406f4>] ? autoremove_wake_function+0x0/0x2e
> > > >> =A0 [<ffffffff81143a4d>] ? elv_rq_merge_ok+0x89/0x97
> > > >> =A0 [<ffffffff8114a245>] ? blk_recount_segments+0x17/0x27
> > > >> =A0 [<ffffffff81147429>] ? __make_request+0x2d6/0x3fc
> > > >> =A0 [<ffffffff81145b16>] ? generic_make_request+0x207/0x268
> > > >> =A0 [<ffffffff81145c12>] ? submit_bio+0x9b/0xa2
> > > >> =A0 [<ffffffffa01aa081>] ? btrfs_requeue_work+0xd7/0xe1 [btrfs=
]
> > > >> =A0 [<ffffffffa01a5365>] ? run_scheduled_bios+0x297/0x48f [btr=
fs]
> > > >> =A0 [<ffffffffa01aa687>] ? worker_loop+0x17c/0x452 [btrfs]
> > > >> =A0 [<ffffffffa01aa50b>] ? worker_loop+0x0/0x452 [btrfs]
> > > >> =A0 [<ffffffff81040331>] ? kthread+0x79/0x81
> > > >> =A0 [<ffffffff81003674>] ? kernel_thread_helper+0x4/0x10
> > > >> =A0 [<ffffffff810402b8>] ? kthread+0x0/0x81
> > > >> =A0 [<ffffffff81003670>] ? kernel_thread_helper+0x0/0x10
> > > > This looks like the issue we saw too, http://lkml.org/lkml/2010=
/6/8/375.
> > > > This is reproduceable in our setup.
> > >=20
> > > I think I know the cause of http://lkml.org/lkml/2010/6/8/375.
> > > The code in the first do-while loop in btrfs_commit_transaction
> > > set current process to TASK_UNINTERRUPTIBLE state, then calls
> > > btrfs_start_delalloc_inodes, btrfs_wait_ordered_extents and
> > > btrfs_run_ordered_operations(). All of these function may call
> > > cond_resched().
> > Hi,
> > When I test random write, I saw a lot of threads jump into btree_wr=
itepages()
> > and do noting and io throughput is zero for some time. Looks like t=
here is a
> > live lock. See the code of btree_writepages():
> > if (wbc->sync_mode =3D=3D WB_SYNC_NONE) {
> > struct btrfs_root *root =3D BTRFS_I(mapping->host)->root;
> > u64 num_dirty;
> > unsigned long thresh =3D 32 * 1024 * 1024;
> >=20
> > if (wbc->for_kupdate)
> > return 0;
> >=20
> > /* this is a bit racy, but that's ok */
> > num_dirty =3D root->fs_info->dirty_metadata_bytes;
> > >>>>>> if (num_dirty < thresh)
> > return 0;
> > }
> > The marked line is quite intrusive. In my test, the live lock is ca=
used by the thresh
> > check. The dirty_metadata_bytes < 32M. Without it, I can't see the =
live lock. Not
> > sure if this is related to the hang.
>=20
> How much ram do you have? The goal of the check is to avoid writing
> metadata blocks because once we write them we have to do more IO to c=
ow
> them again if they are changed later.
>=20
> It shouldn't be looping hard in btrfs there, what was the workload?
This is a fio randomwrite. Yep, I limited memory to a small size (~500M=
), because it makes
me easily to produce a 'xxx blocked for more than 120 seconds' issue. I=
can understand small
memory could be an issue, but this still looks intrusive, right?
The issue Yanmin reported is under 2.6.35-rc1, so might not be the
'TASK_UNINTERRUPTIBLE' issue, but we will try -rc3 too.
Thanks,
Shaohua
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^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: btrfs: hanging processes - race condition?
2010-06-17 1:41 ` Shaohua Li
@ 2010-06-18 0:57 ` Shaohua Li
0 siblings, 0 replies; 12+ messages in thread
From: Shaohua Li @ 2010-06-18 0:57 UTC (permalink / raw)
To: Chris Mason, Yan, Zheng , Jerome Ibanes, linux-btrfs,
On Thu, Jun 17, 2010 at 09:41:18AM +0800, Shaohua Li wrote:
> On Mon, Jun 14, 2010 at 09:28:29PM +0800, Chris Mason wrote:
> > On Sun, Jun 13, 2010 at 02:50:06PM +0800, Shaohua Li wrote:
> > > On Fri, Jun 11, 2010 at 10:32:07AM +0800, Yan, Zheng wrote:
> > > > On Fri, Jun 11, 2010 at 9:12 AM, Shaohua Li <shaohua.li@intel.c=
om> wrote:
> > > > > On Fri, Jun 11, 2010 at 01:41:41AM +0800, Jerome Ibanes wrote=
:
> > > > >> List,
> > > > >>
> > > > >> I ran into a hang issue (race condition: cpu is high when th=
e server is
> > > > >> idle, meaning that btrfs is hanging, and IOwait is high as w=
ell) running
> > > > >> 2.6.34 on debian/lenny on a x86_64 server (dual Opteron 275 =
w/ 16GB ram).
> > > > >> The btrfs filesystem live on 18x300GB scsi spindles, configu=
red as Raid-0,
> > > > >> as shown below:
> > > > >>
> > > > >> Label: none =A0uuid: bc6442c6-2fe2-4236-a5aa-6b7841234c52
> > > > >> =A0 =A0 =A0 =A0 =A0Total devices 18 FS bytes used 2.94TB
> > > > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A05 size 279.39GB used 208.33G=
B path /dev/cciss/c1d0
> > > > >> =A0 =A0 =A0 =A0 =A0devid =A0 17 size 279.39GB used 208.34GB =
path /dev/cciss/c1d8
> > > > >> =A0 =A0 =A0 =A0 =A0devid =A0 16 size 279.39GB used 209.33GB =
path /dev/cciss/c1d7
> > > > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A04 size 279.39GB used 208.33G=
B path /dev/cciss/c0d4
> > > > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A01 size 279.39GB used 233.72G=
B path /dev/cciss/c0d1
> > > > >> =A0 =A0 =A0 =A0 =A0devid =A0 13 size 279.39GB used 208.33GB =
path /dev/cciss/c1d4
> > > > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A08 size 279.39GB used 208.33G=
B path /dev/cciss/c1d11
> > > > >> =A0 =A0 =A0 =A0 =A0devid =A0 12 size 279.39GB used 208.33GB =
path /dev/cciss/c1d3
> > > > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A03 size 279.39GB used 208.33G=
B path /dev/cciss/c0d3
> > > > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A09 size 279.39GB used 208.33G=
B path /dev/cciss/c1d12
> > > > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A06 size 279.39GB used 208.33G=
B path /dev/cciss/c1d1
> > > > >> =A0 =A0 =A0 =A0 =A0devid =A0 11 size 279.39GB used 208.33GB =
path /dev/cciss/c1d2
> > > > >> =A0 =A0 =A0 =A0 =A0devid =A0 14 size 279.39GB used 208.33GB =
path /dev/cciss/c1d5
> > > > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A02 size 279.39GB used 233.70G=
B path /dev/cciss/c0d2
> > > > >> =A0 =A0 =A0 =A0 =A0devid =A0 15 size 279.39GB used 209.33GB =
path /dev/cciss/c1d6
> > > > >> =A0 =A0 =A0 =A0 =A0devid =A0 10 size 279.39GB used 208.33GB =
path /dev/cciss/c1d13
> > > > >> =A0 =A0 =A0 =A0 =A0devid =A0 =A07 size 279.39GB used 208.33G=
B path /dev/cciss/c1d10
> > > > >> =A0 =A0 =A0 =A0 =A0devid =A0 18 size 279.39GB used 208.34GB =
path /dev/cciss/c1d9
> > > > >> Btrfs v0.19-16-g075587c-dirty
> > > > >>
> > > > >> The filesystem, mounted in /mnt/btrfs is hanging, no existin=
g or new
> > > > >> process can access it, however 'df' still displays the disk =
usage (3TB out
> > > > >> of 5). The disks appear to be physically healthy. Please not=
e that a
> > > > >> significant number of files were placed on this filesystem, =
between 20 and
> > > > >> 30 million files.
> > > > >>
> > > > >> The relevant kernel messages are displayed below:
> > > > >>
> > > > >> INFO: task btrfs-submit-0:4220 blocked for more than 120 sec=
onds.
> > > > >> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables =
this message.
> > > > >> btrfs-submit- D 000000010042e12f =A0 =A0 0 =A04220 =A0 =A0 =A0=
2 0x00000000
> > > > >> =A0 ffff8803e584ac70 0000000000000046 0000000000004000 00000=
00000011680
> > > > >> =A0 ffff8803f7349fd8 ffff8803f7349fd8 ffff8803e584ac70 00000=
00000011680
> > > > >> =A0 0000000000000001 ffff8803ff99d250 ffffffff8149f020 00000=
00081150ab0
> > > > >> Call Trace:
> > > > >> =A0 [<ffffffff813089f3>] ? io_schedule+0x71/0xb1
> > > > >> =A0 [<ffffffff811470be>] ? get_request_wait+0xab/0x140
> > > > >> =A0 [<ffffffff810406f4>] ? autoremove_wake_function+0x0/0x2e
> > > > >> =A0 [<ffffffff81143a4d>] ? elv_rq_merge_ok+0x89/0x97
> > > > >> =A0 [<ffffffff8114a245>] ? blk_recount_segments+0x17/0x27
> > > > >> =A0 [<ffffffff81147429>] ? __make_request+0x2d6/0x3fc
> > > > >> =A0 [<ffffffff81145b16>] ? generic_make_request+0x207/0x268
> > > > >> =A0 [<ffffffff81145c12>] ? submit_bio+0x9b/0xa2
> > > > >> =A0 [<ffffffffa01aa081>] ? btrfs_requeue_work+0xd7/0xe1 [btr=
fs]
> > > > >> =A0 [<ffffffffa01a5365>] ? run_scheduled_bios+0x297/0x48f [b=
trfs]
> > > > >> =A0 [<ffffffffa01aa687>] ? worker_loop+0x17c/0x452 [btrfs]
> > > > >> =A0 [<ffffffffa01aa50b>] ? worker_loop+0x0/0x452 [btrfs]
> > > > >> =A0 [<ffffffff81040331>] ? kthread+0x79/0x81
> > > > >> =A0 [<ffffffff81003674>] ? kernel_thread_helper+0x4/0x10
> > > > >> =A0 [<ffffffff810402b8>] ? kthread+0x0/0x81
> > > > >> =A0 [<ffffffff81003670>] ? kernel_thread_helper+0x0/0x10
> > > > > This looks like the issue we saw too, http://lkml.org/lkml/20=
10/6/8/375.
> > > > > This is reproduceable in our setup.
> > > >=20
> > > > I think I know the cause of http://lkml.org/lkml/2010/6/8/375.
> > > > The code in the first do-while loop in btrfs_commit_transaction
> > > > set current process to TASK_UNINTERRUPTIBLE state, then calls
> > > > btrfs_start_delalloc_inodes, btrfs_wait_ordered_extents and
> > > > btrfs_run_ordered_operations(). All of these function may call
> > > > cond_resched().
> > > Hi,
> > > When I test random write, I saw a lot of threads jump into btree_=
writepages()
> > > and do noting and io throughput is zero for some time. Looks like=
there is a
> > > live lock. See the code of btree_writepages():
> > > if (wbc->sync_mode =3D=3D WB_SYNC_NONE) {
> > > struct btrfs_root *root =3D BTRFS_I(mapping->host)->root;
> > > u64 num_dirty;
> > > unsigned long thresh =3D 32 * 1024 * 1024;
> > >=20
> > > if (wbc->for_kupdate)
> > > return 0;
> > >=20
> > > /* this is a bit racy, but that's ok */
> > > num_dirty =3D root->fs_info->dirty_metadata_bytes;
> > > >>>>>> if (num_dirty < thresh)
> > > return 0;
> > > }
> > > The marked line is quite intrusive. In my test, the live lock is =
caused by the thresh
> > > check. The dirty_metadata_bytes < 32M. Without it, I can't see th=
e live lock. Not
> > > sure if this is related to the hang.
> >=20
> > How much ram do you have? The goal of the check is to avoid writin=
g
> > metadata blocks because once we write them we have to do more IO to=
cow
> > them again if they are changed later.
> >=20
> > It shouldn't be looping hard in btrfs there, what was the workload?
> This is a fio randomwrite. Yep, I limited memory to a small size (~50=
0M), because it makes
> me easily to produce a 'xxx blocked for more than 120 seconds' issue.=
I can understand small
> memory could be an issue, but this still looks intrusive, right?
>=20
> The issue Yanmin reported is under 2.6.35-rc1, so might not be the
> 'TASK_UNINTERRUPTIBLE' issue, but we will try -rc3 too.
I still get below message with 2.6.35-rc3. The system is still running,=
because
my fio test finished even with the message.
INFO: task flush-btrfs-134:14144 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this messag=
e.
flush-btrfs-1 D 0000000100346d5c 4480 14144 2 0x00000000
ffff88016fd51530 0000000000000046 0000000000000001 ffff880100000000
ffff88023ef0f100 0000000000013ac0 0000000000013ac0 0000000000004000
0000000000013ac0 ffff88018be2dfd8 ffff88016fd51530 ffff88018be2dfd8
Call Trace:
[<ffffffff8124be61>] ? wait_block_group_cache_progress+0xc0/0xe4
[<ffffffff81052977>] ? autoremove_wake_function+0x0/0x2a
[<ffffffff81052977>] ? autoremove_wake_function+0x0/0x2a
[<ffffffff8124f956>] ? find_free_extent+0x694/0x9c4
[<ffffffff8124fd53>] ? btrfs_reserve_extent+0xcd/0x189
[<ffffffff81262803>] ? cow_file_range+0x19e/0x2fc
[<ffffffff81262fe0>] ? run_delalloc_range+0xa7/0x393
[<ffffffff8127832e>] ? test_range_bit+0x2b/0x127
[<ffffffff8127b44e>] ? find_lock_delalloc_range+0x1af/0x1d1
[<ffffffff8127b655>] ? __extent_writepage+0x1e5/0x61f
[<ffffffff812c1fac>] ? prio_tree_next+0x1c0/0x221
[<ffffffff812bf3c8>] ? cpumask_any_but+0x28/0x37
[<ffffffff810b4af7>] ? page_mkclean+0x120/0x148
[<ffffffff8127bed2>] ? extent_write_cache_pages.clone.0+0x15e/0x26c
[<ffffffff8127c0db>] ? extent_writepages+0x41/0x5a
[<ffffffff81264319>] ? btrfs_get_extent+0x0/0x798
[<ffffffff810e6fcb>] ? writeback_single_inode+0xd1/0x2e8
[<ffffffff810e7d02>] ? writeback_inodes_wb+0x40d/0x51f
[<ffffffff810e7f47>] ? wb_writeback+0x133/0x1b2
[<ffffffff810e81ae>] ? wb_do_writeback+0x148/0x15e
[<ffffffff810e81fe>] ? bdi_writeback_task+0x3a/0x113
[<ffffffff81052897>] ? bit_waitqueue+0x14/0xa4
[<ffffffff810a9b19>] ? bdi_start_fn+0x0/0xc2
[<ffffffff810a9b7c>] ? bdi_start_fn+0x63/0xc2
[<ffffffff810a9b19>] ? bdi_start_fn+0x0/0xc2
[<ffffffff81052525>] ? kthread+0x75/0x7d
[<ffffffff81003654>] ? kernel_thread_helper+0x4/0x10
[<ffffffff810524b0>] ? kthread+0x0/0x7d
[<ffffffff81003650>] ? kernel_thread_helper+0x0/0x10
=20
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^ permalink raw reply [flat|nested] 12+ messages in thread
end of thread, other threads:[~2010-06-18 0:57 UTC | newest]
Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2010-06-10 17:41 btrfs: hanging processes - race condition? Jerome Ibanes
2010-06-11 1:12 ` Shaohua Li
2010-06-11 2:32 ` Yan, Zheng
2010-06-13 6:50 ` Shaohua Li
2010-06-14 13:28 ` Chris Mason
2010-06-14 18:12 ` Jerome Ibanes
2010-06-14 19:08 ` Chris Mason
2010-06-14 19:13 ` Jerome Ibanes
2010-06-16 18:12 ` Jerome Ibanes
2010-06-17 1:41 ` Shaohua Li
2010-06-18 0:57 ` Shaohua Li
2010-06-14 13:26 ` Chris Mason
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