Looks like the same problem with spinlock unfairness we've seen elsewhere: it seems to be looping here? Or is everyone stuck just waiting for writeout?
lock_timer_base(): for (;;) { tvec_base_t *prelock_base = timer->base; base = tbase_get_base(prelock_base); if (likely(base != NULL)) { spin_lock_irqsave(&base->lock, *flags); if (likely(prelock_base == timer->base)) return base; /* The timer has migrated to another CPU */ spin_unlock_irqrestore(&base->lock, *flags); } cpu_relax(); } The problem goes away completely if filesystem are mounted *without* noatime. Has happened in 2.6.20 through 2.6.22... https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=249563 Part of sysrq-t listing: mysqld D 000017c0 2196 23162 1562 e383fcb8 00000082 61650954 000017c0 e383fc9c 00000000 c0407208 e383f000 a12b0434 00004d1d c6ed2c00 c6ed2d9c c200fa80 00000000 c0724640 f6c60540 c4ff3c70 00000508 00000286 c042ffcb e383fcc8 00014926 00000000 00000286 Call Trace: [<c0407208>] do_IRQ+0xbd/0xd1 [<c042ffcb>] lock_timer_base+0x19/0x35 [<c04300df>] __mod_timer+0x9a/0xa4 [<c060bb55>] schedule_timeout+0x70/0x8f [<c042fd37>] process_timeout+0x0/0x5 [<c060bb50>] schedule_timeout+0x6b/0x8f [<c060b67c>] io_schedule_timeout+0x39/0x5d [<c0465eea>] congestion_wait+0x50/0x64 [<c0438539>] autoremove_wake_function+0x0/0x35 [<c04620e2>] balance_dirty_pages_ratelimited_nr+0x148/0x193 [<c045e7fd>] generic_file_buffered_write+0x4c7/0x5d3 named D 000017c0 2024 1454 1 f722acb0 00000082 6165ed96 000017c0 c1523e80 c16f0c00 c16f20e0 f722a000 a12be87d 00004d1d f768ac00 f768ad9c c200fa80 00000000 00000000 f75bda80 c0407208 00000508 00000286 c042ffcb f722acc0 00020207 00000000 00000286 Call Trace: [<c0407208>] do_IRQ+0xbd/0xd1 [<c042ffcb>] lock_timer_base+0x19/0x35 [<c04300df>] __mod_timer+0x9a/0xa4 [<c060bb55>] schedule_timeout+0x70/0x8f [<c042fd37>] process_timeout+0x0/0x5 [<c060bb50>] schedule_timeout+0x6b/0x8f [<c060b67c>] io_schedule_timeout+0x39/0x5d [<c0465eea>] congestion_wait+0x50/0x64 [<c0438539>] autoremove_wake_function+0x0/0x35 [<c04620e2>] balance_dirty_pages_ratelimited_nr+0x148/0x193 [<c045e7fd>] generic_file_buffered_write+0x4c7/0x5d3 mysqld D 000017c0 2196 23456 1562 e9293cb8 00000082 616692ed 000017c0 e9293c9c 00000000 e9293cc8 e9293000 a12c8dd0 00004d1d c3d5ac00 c3d5ad9c c200fa80 00000000 c0724640 f6c60540 e9293d10 c07e1f00 00000286 c042ffcb e9293cc8 0002b57f 00000000 00000286 Call Trace: [<c042ffcb>] lock_timer_base+0x19/0x35 [<c04300df>] __mod_timer+0x9a/0xa4 [<c060bb55>] schedule_timeout+0x70/0x8f [<c042fd37>] process_timeout+0x0/0x5 [<c060bb50>] schedule_timeout+0x6b/0x8f [<c060b67c>] io_schedule_timeout+0x39/0x5d [<c0465eea>] congestion_wait+0x50/0x64 [<c0438539>] autoremove_wake_function+0x0/0x35 [<c04620e2>] balance_dirty_pages_ratelimited_nr+0x148/0x193 [<c045e7fd>] generic_file_buffered_write+0x4c7/0x5d3 - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/