From mboxrd@z Thu Jan 1 00:00:00 1970 From: Shaohua Li Subject: Re: btrfs: hanging processes - race condition? Date: Fri, 11 Jun 2010 09:12:42 +0800 Message-ID: <20100611011242.GA22585@sli10-desk.sh.intel.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "linux-btrfs@vger.kernel.org" , yanmin.zhang@intel.com, tim.c.chen@intel.com To: Jerome Ibanes Return-path: In-Reply-To: List-ID: 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: > [] ? io_schedule+0x71/0xb1 > [] ? get_request_wait+0xab/0x140 > [] ? autoremove_wake_function+0x0/0x2e > [] ? elv_rq_merge_ok+0x89/0x97 > [] ? blk_recount_segments+0x17/0x27 > [] ? __make_request+0x2d6/0x3fc > [] ? generic_make_request+0x207/0x268 > [] ? submit_bio+0x9b/0xa2 > [] ? btrfs_requeue_work+0xd7/0xe1 [btrfs] > [] ? run_scheduled_bios+0x297/0x48f [btrfs] > [] ? worker_loop+0x17c/0x452 [btrfs] > [] ? worker_loop+0x0/0x452 [btrfs] > [] ? kthread+0x79/0x81 > [] ? kernel_thread_helper+0x4/0x10 > [] ? kthread+0x0/0x81 > [] ? 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