Messages in this thread | | | Date | Wed, 31 Oct 2007 16:22:10 +0100 | From | "Torsten Kaiser" <> | Subject | Re: 100% iowait on one of cpus in current -git |
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On 10/22/07, Fengguang Wu <wfg@mail.ustc.edu.cn> wrote: > On Mon, Oct 22, 2007 at 09:10:45PM +0800, Fengguang Wu wrote: > > Hmm, Maybe it's an reiserfs related issue. Do you have the full log file? > > Bingo! It can be reproduced in -mm on reiserfs: > > # mkfs.reiserfs /dev/sdb1 > # mount /dev/sdb1 /test > # cp bin /test > <wait for a while> > # dmesg > [...] > [ 418.346113] requeue_io 308: inode 6 size 302 at 08:11(sdb1) > [ 418.346119] requeue_io 308: inode 7 size 196 at 08:11(sdb1) > [ 418.346125] requeue_io 308: inode 8 size 85 at 08:11(sdb1)
Since 2.6.23-mm1 I also experience strange hangs during heavy writeouts. Each time I noticed this I was using emerge (package util from the gentoo distribution) to install/upgrade a package. The last step, where this hang occurred, is moving the prepared files from a tmpfs partion to the main xfs filesystem. The hangs where not fatal, after a few second everything resumed normal, so I was not able to capture a good image of what was happening.
Today it happend again, but a little more obvious. During the moving process the writeout stalled completly for several minutes until I hit SysRq+W.
/proc/meminfo: MemTotal: 4061808 kB MemFree: 881332 kB Buffers: 0 kB Cached: 2566628 kB SwapCached: 64 kB Active: 926612 kB Inactive: 1959136 kB SwapTotal: 9775416 kB SwapFree: 9775296 kB Dirty: 44948 kB Writeback: 0 kB AnonPages: 319068 kB Mapped: 52844 kB Slab: 235572 kB SReclaimable: 164408 kB SUnreclaim: 71164 kB PageTables: 9576 kB NFS_Unstable: 0 kB Bounce: 0 kB CommitLimit: 11806320 kB Committed_AS: 544520 kB VmallocTotal: 34359738367 kB VmallocUsed: 35004 kB VmallocChunk: 34359702447 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 2048 kB
The 'Dirty' count did not decrease during this time and 'Writeback' stayed at 0. I also have /proc/pagetypeinfo ,but I see nothing interessing in there. (But will send it, if needed)
The output from SysRq+W: SysRq : Show Blocked State task PC stack pid father pdflush D ffff81001fcc2a88 0 285 2 ffff810005d55580 0000000000000046 0000000000000800 0000007000000001 0000000000000400 ffffffff8022d61c ffffffff80817b00 ffffffff80817b00 ffffffff80813f40 ffffffff80817b00 ffff810100893b18 0000000000000000 Call Trace: [<ffffffff8022d61c>] task_rq_lock+0x4c/0x90 [<ffffffff8022c8ea>] __wake_up_common+0x5a/0x90 [<ffffffff805b14c7>] __down+0xa7/0x11e [<ffffffff8022da70>] default_wake_function+0x0/0x10 [<ffffffff805b1145>] __down_failed+0x35/0x3a [<ffffffff803750be>] xfs_buf_lock+0x3e/0x40 [<ffffffff803771fe>] _xfs_buf_find+0x13e/0x240 [<ffffffff8037736f>] xfs_buf_get_flags+0x6f/0x190 [<ffffffff803774a2>] xfs_buf_read_flags+0x12/0xa0 [<ffffffff80368614>] xfs_trans_read_buf+0x64/0x340 [<ffffffff80352151>] xfs_itobp+0x81/0x1e0 [<ffffffff803759de>] xfs_buf_rele+0x2e/0xd0 [<ffffffff80354afe>] xfs_iflush+0xfe/0x520 [<ffffffff803ae3b2>] __down_read_trylock+0x42/0x60 [<ffffffff80355a72>] xfs_inode_item_push+0x12/0x20 [<ffffffff80368037>] xfs_trans_push_ail+0x267/0x2b0 [<ffffffff8035a33b>] xlog_ticket_get+0xfb/0x140 [<ffffffff8035c5ae>] xfs_log_reserve+0xee/0x120 [<ffffffff803669e8>] xfs_trans_reserve+0xa8/0x210 [<ffffffff8035703a>] xfs_iomap_write_allocate+0xfa/0x410 [<ffffffff804ce67a>] __split_bio+0x38a/0x3c0 [<ffffffff80373657>] xfs_start_page_writeback+0x27/0x60 [<ffffffff8035660c>] xfs_iomap+0x26c/0x310 [<ffffffff803735d8>] xfs_map_blocks+0x38/0x90 [<ffffffff80374a88>] xfs_page_state_convert+0x2b8/0x630 [<ffffffff80374f5f>] xfs_vm_writepage+0x6f/0x120 [<ffffffff8026acda>] __writepage+0xa/0x30 [<ffffffff8026b2ce>] write_cache_pages+0x23e/0x330 [<ffffffff8026acd0>] __writepage+0x0/0x30 [<ffffffff80354db7>] xfs_iflush+0x3b7/0x520 [<ffffffff80375782>] _xfs_buf_ioapply+0x222/0x320 [<ffffffff803ae451>] __up_read+0x21/0xb0 [<ffffffff8034f22c>] xfs_iunlock+0x5c/0xc0 [<ffffffff8026b410>] do_writepages+0x20/0x40 [<ffffffff802b36a0>] __writeback_single_inode+0xb0/0x380 [<ffffffff804d052e>] dm_table_any_congested+0x2e/0x80 [<ffffffff802b3d8d>] generic_sync_sb_inodes+0x20d/0x330 [<ffffffff802b4322>] writeback_inodes+0xa2/0xe0 [<ffffffff8026bde6>] wb_kupdate+0xa6/0x120 [<ffffffff8026c2a0>] pdflush+0x0/0x1e0 [<ffffffff8026c3b0>] pdflush+0x110/0x1e0 [<ffffffff8026bd40>] wb_kupdate+0x0/0x120 [<ffffffff8024a32b>] kthread+0x4b/0x80 [<ffffffff8020c9d8>] child_rip+0xa/0x12 [<ffffffff8024a2e0>] kthread+0x0/0x80 [<ffffffff8020c9ce>] child_rip+0x0/0x12
emerge D ffff81001fcc2a88 0 3221 8163 ffff81008c0679f8 0000000000000086 ffff81008c067988 ffffffff8024a719 ffff8100060fb008 ffffffff8022c8ea ffffffff80817b00 ffffffff80817b00 ffffffff80813f40 ffffffff80817b00 ffff810100893b18 0000000000000000 Call Trace: [<ffffffff8024a719>] autoremove_wake_function+0x9/0x30 [<ffffffff8022c8ea>] __wake_up_common+0x5a/0x90 [<ffffffff8022c8ea>] __wake_up_common+0x5a/0x90 [<ffffffff805b14c7>] __down+0xa7/0x11e [<ffffffff8022da70>] default_wake_function+0x0/0x10 [<ffffffff805b1145>] __down_failed+0x35/0x3a [<ffffffff803750be>] xfs_buf_lock+0x3e/0x40 [<ffffffff803771fe>] _xfs_buf_find+0x13e/0x240 [<ffffffff8037736f>] xfs_buf_get_flags+0x6f/0x190 [<ffffffff803774a2>] xfs_buf_read_flags+0x12/0xa0 [<ffffffff80368614>] xfs_trans_read_buf+0x64/0x340 [<ffffffff80352151>] xfs_itobp+0x81/0x1e0 [<ffffffff803759de>] xfs_buf_rele+0x2e/0xd0 [<ffffffff80354afe>] xfs_iflush+0xfe/0x520 [<ffffffff803ae3b2>] __down_read_trylock+0x42/0x60 [<ffffffff80355a72>] xfs_inode_item_push+0x12/0x20 [<ffffffff80368037>] xfs_trans_push_ail+0x267/0x2b0 [<ffffffff8035c532>] xfs_log_reserve+0x72/0x120 [<ffffffff803669e8>] xfs_trans_reserve+0xa8/0x210 [<ffffffff80372fe2>] kmem_zone_zalloc+0x32/0x50 [<ffffffff8035242b>] xfs_itruncate_finish+0xfb/0x310 [<ffffffff8036d8db>] xfs_free_eofblocks+0x23b/0x280 [<ffffffff80371d83>] xfs_release+0x153/0x200 [<ffffffff80377e00>] xfs_file_release+0x10/0x20 [<ffffffff80294041>] __fput+0xb1/0x220 [<ffffffff80290e94>] filp_close+0x54/0x90 [<ffffffff802927af>] sys_close+0x9f/0x100 [<ffffffff8020bbbe>] system_call+0x7e/0x83
After this SysRq+W writeback resumed again. Possible that writing above into the syslog triggered that. The source tmpfs is mounted with any special parameters, but the target xfs filesystem resides on a dm-crypt device that is on top a 3 disk RAID5 md. During the hang all CPUs where idle. The system is x86_64 with CONFIG_NO_HZ=y, but was still receiving ~330 interrupts per second because of the bttv driver. (But I was not using that device at this time.)
I'm willing to test patches or more provide more information, but lack a good testcase to trigger this on demand.
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