On Fri, 23 Mar 2012 12:45:03 +0200 Sasha Levin <levinsasha928@xxxxxxxxx> wrote: > Hi guys, > > During fuzzing using trinity inside a KVM tools guest with latest > linux-next, I seem to be getting it hung once in a while, with the > following spew: > > [ 1441.420617] INFO: task trinity:2706 blocked for more than 120 seconds. > [ 1441.421894] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" > disables this message. > [ 1441.424493] trinity D 0000000000000000 3472 2706 16846 0x00000004 > [ 1441.426749] ffff880029dbbb38 0000000000000086 ffff880029dbbae8 > ffff880029dbbfd8 > [ 1441.428582] 00000000001d45c0 ffff880029dba000 00000000001d45c0 > 00000000001d45c0 > [ 1441.430156] 00000000001d45c0 00000000001d45c0 ffff880029dbbfd8 > 00000000001d45c0 > [ 1441.432371] Call Trace: > [ 1441.433042] [<ffffffff81176dd0>] ? file_read_actor+0x1d0/0x1d0 > [ 1441.434251] [<ffffffff827148d4>] schedule+0x24/0x70 > [ 1441.435314] [<ffffffff82714e67>] io_schedule+0x87/0xd0 > [ 1441.436357] [<ffffffff81176dd9>] sleep_on_page+0x9/0x10 > [ 1441.437442] [<ffffffff82712cb7>] __wait_on_bit+0x57/0x80 > [ 1441.438584] [<ffffffff81177bff>] ? __lock_page_or_retry+0x8f/0xd0 > [ 1441.439948] [<ffffffff811775de>] wait_on_page_bit+0x6e/0x80 > [ 1441.440859] [<ffffffff810d6d20>] ? autoremove_wake_function+0x40/0x40 > [ 1441.441700] [<ffffffff810dbfbe>] ? up_read+0x1e/0x40 > [ 1441.442428] [<ffffffff81177c36>] __lock_page_or_retry+0xc6/0xd0 > [ 1441.443270] [<ffffffff81178490>] filemap_fault+0x440/0x4e0 > [ 1441.444072] [<ffffffff811991cf>] __do_fault+0x7f/0x5f0 > [ 1441.444829] [<ffffffff81112c00>] ? > add_lock_to_list.clone.18.clone.27+0xd0/0xe0 > [ 1441.445886] [<ffffffff8119cd27>] handle_pte_fault+0xf7/0x1e0 > [ 1441.446740] [<ffffffff8119e1ce>] handle_mm_fault+0x1ce/0x330 > [ 1441.447537] [<ffffffff8119e53c>] __get_user_pages+0x14c/0x640 > [ 1441.448399] [<ffffffff811129ae>] ? put_lock_stats.clone.19+0xe/0x40 > [ 1441.449288] [<ffffffff81117b1d>] ? __lock_acquired+0x19d/0x270 > [ 1441.450164] [<ffffffff811a0087>] __mlock_vma_pages_range+0x87/0xa0 > [ 1441.451127] [<ffffffff811a0129>] do_mlock_pages+0x89/0x160 > [ 1441.451932] [<ffffffff811a0b71>] sys_mlockall+0x111/0x1a0 > [ 1441.452761] [<ffffffff827176bd>] system_call_fastpath+0x1a/0x1f > [ 1441.453659] no locks held by trinity/2706. > [ 1441.454267] Kernel panic - not syncing: hung_task: blocked tasks > > According to the logs, it's not the direct result of anything specific > happening, so I can't give an exact scenario to reproduce it. It does > happen rather often. The task is waiting for IO to complete against a page, and it isn't happening. There are quite a lot of things which could cause this, alas. VM, readahead, scheduler, core wait/wakeup code, IO system, interrupt system (if it happens outside KVM, I guess). So.... ugh. Hopefully someone will hit this in a situation where it can be narrowed down or bisected. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>