On Tue 10-10-17 09:28:51, Dave Chinner wrote: > On Mon, Oct 09, 2017 at 08:31:29PM +0200, Luis R. Rodriguez wrote: > > On Mon, Oct 09, 2017 at 11:05:29AM +1100, Dave Chinner wrote: > > > On Sat, Oct 07, 2017 at 01:10:58PM +0500, Михаил Гаврилов wrote: > > > > But seems now got another issue: > > > > > > > > [ 1966.953781] INFO: task tracker-store:8578 blocked for more than 120 seconds. > > > > [ 1966.953797] Not tainted 4.13.4-301.fc27.x86_64+debug #1 > > > > [ 1966.953800] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" > > > > disables this message. > > > > [ 1966.953804] tracker-store D12840 8578 1655 0x00000000 > > > > [ 1966.953811] Call Trace: > > > > [ 1966.953823] __schedule+0x2dc/0xbb0 > > > > [ 1966.953830] ? wait_on_page_bit_common+0xfb/0x1a0 > > > > [ 1966.953838] schedule+0x3d/0x90 > > > > [ 1966.953843] io_schedule+0x16/0x40 > > > > [ 1966.953847] wait_on_page_bit_common+0x10a/0x1a0 > > > > [ 1966.953857] ? page_cache_tree_insert+0x170/0x170 > > > > [ 1966.953865] __filemap_fdatawait_range+0x101/0x1a0 > > > > [ 1966.953883] file_write_and_wait_range+0x63/0xc0 > > > > > > Ok, that's in wait_on_page_writeback(page) > > > ...... > > > > > > > And yet another > > > > > > > > [41288.797026] INFO: task tracker-store:4535 blocked for more than 120 seconds. > > > > [41288.797034] Not tainted 4.13.4-301.fc27.x86_64+debug #1 > > > > [41288.797037] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" > > > > disables this message. > > > > [41288.797041] tracker-store D10616 4535 1655 0x00000000 > > > > [41288.797049] Call Trace: > > > > [41288.797061] __schedule+0x2dc/0xbb0 > > > > [41288.797072] ? bit_wait+0x60/0x60 > > > > [41288.797076] schedule+0x3d/0x90 > > > > [41288.797082] io_schedule+0x16/0x40 > > > > [41288.797086] bit_wait_io+0x11/0x60 > > > > [41288.797091] __wait_on_bit+0x31/0x90 > > > > [41288.797099] out_of_line_wait_on_bit+0x94/0xb0 > > > > [41288.797106] ? bit_waitqueue+0x40/0x40 > > > > [41288.797113] __block_write_begin_int+0x265/0x550 > > > > [41288.797132] iomap_write_begin.constprop.14+0x7d/0x130 > > > > > > And that's in wait_on_buffer(). > > > > > > In both cases we are waiting on a bit lock for IO completion. In the > > > first case it is on page, the second it's on sub-page read IO > > > completion during a write. > > > > > > Triggeringa hung task timeouts like this doesn't usually indicate a > > > filesystem problem. > > > > <-- snip --> > > > > > None of these things usually filesystem problems, and the trainsmash > > > of blocked tasks on filesystem locks is typical for these types of > > > "blocked indefinitely with locks held" type of situations. It does > > > tend to indicate taht there is quite a bit of load on the > > > filesystem, though... > > > > As Jan Kara noted we've seen this also on customers SLE12-SP2 kernel (4.4 > > based). Although we also were never able to root cause, since that bug > > is now closed on our end I figured it would be worth mentioning two > > theories we discussed, one more recent than the other. > > Sure, but stuff going on with docker mounts and namespaces has > nothing to do with IO path locking and completions. There's > something in the filesystem or the storage stack below going > wrong here, not above it in the vfsmount layer.... Agreed. If anything, I suspect there's somewhere some race when we tear down process' mappings when handling SIGKILL. But I was never able to reproduce nor find any problem in the code... Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR -- 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/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
