Hi, I've got a report of xfs_aild blocking system suspend in 4.8.7 (in openSUSE Tumbleweed which is our rolling distro): Freezing of tasks failed after 20.003 seconds (1 tasks refusing to freeze, wq_busy=0): xfsaild/sdb3 D 0000000000019680 0 918 2 0x00000080 ffff9e685409fb88 0000000000000000 ffff9e67beaea080 ffff9e68504c6000 ffff9e6677226b80 ffff9e68540a0000 ffff9e676068c6d8 ffff9e68504c6000 ffff9e685e48dc00 ffff9e676068c600 ffff9e685409fba0 ffffffffb66cfbac Call Trace: [<ffffffffb66cfbac>] schedule+0x3c/0x90 [<ffffffffb66d2f1e>] schedule_timeout+0x22e/0x410 [<ffffffffb66d0f4a>] wait_for_completion+0x9a/0x100 [<ffffffffc0f0689e>] xfs_buf_submit_wait+0x7e/0x250 [xfs] [<ffffffffc0f06ba8>] xfs_buf_read_map+0x108/0x190 [xfs] [<ffffffffc0f340c0>] xfs_trans_read_buf_map+0x100/0x370 [xfs] [<ffffffffc0ef631e>] xfs_imap_to_bp+0x5e/0xd0 [xfs] [<ffffffffc0f1ac6a>] xfs_iflush+0xca/0x220 [xfs] [<ffffffffc0f2b21b>] xfs_inode_item_push+0xcb/0x120 [xfs] [<ffffffffc0f32e8e>] xfsaild+0x30e/0x770 [xfs] [<ffffffffb609c5ed>] kthread+0xbd/0xe0 [<ffffffffb66d459f>] ret_from_fork+0x1f/0x40 DWARF2 unwinder stuck at ret_from_fork+0x1f/0x40 Leftover inexact backtrace: [<ffffffffb609c530>] ? kthread_worker_fn+0x170/0x170 What I think has happened is that b_ioend_wq got already frozen during suspend and thus submitted read could not be completed (all buffer IO completions seem to be happening from workqueue now if I'm reading the code right) and thus xfs_aild never finished waiting for IO so that it could be frozen in try_to_freeze(). I'm not sure how to best fix this since I don't think we can easily have suspend dependencies between different execution contexts... We could possibly complete buffer IO already from softirq (which should also reduce IO latency somewhat) if it does not have ->iodone callback but maybe there's some problem with it I'm missing. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR -- To unsubscribe from this list: send the line "unsubscribe linux-xfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
