linux-stable/fs/xfs/scrub
Darrick J. Wong 5d1116d4c6 xfs: periodically yield scrub threads to the scheduler
Christoph Hellwig complained about the following soft lockup warning
when running scrub after generic/175 when preemption is disabled and
slub debugging is enabled:

watchdog: BUG: soft lockup - CPU#3 stuck for 22s! [xfs_scrub:161]
Modules linked in:
irq event stamp: 41692326
hardirqs last  enabled at (41692325): [<ffffffff8232c3b7>] _raw_0
hardirqs last disabled at (41692326): [<ffffffff81001c5a>] trace0
softirqs last  enabled at (41684994): [<ffffffff8260031f>] __do_e
softirqs last disabled at (41684987): [<ffffffff81127d8c>] irq_e0
CPU: 3 PID: 16189 Comm: xfs_scrub Not tainted 5.4.0-rc3+ #30
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.124
RIP: 0010:_raw_spin_unlock_irqrestore+0x39/0x40
Code: 89 f3 be 01 00 00 00 e8 d5 3a e5 fe 48 89 ef e8 ed 87 e5 f2
RSP: 0018:ffffc9000233f970 EFLAGS: 00000286 ORIG_RAX: ffffffffff3
RAX: ffff88813b398040 RBX: 0000000000000286 RCX: 0000000000000006
RDX: 0000000000000006 RSI: ffff88813b3988c0 RDI: ffff88813b398040
RBP: ffff888137958640 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffea00042b0c00
R13: 0000000000000001 R14: ffff88810ac32308 R15: ffff8881376fc040
FS:  00007f6113dea700(0000) GS:ffff88813bb80000(0000) knlGS:00000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f6113de8ff8 CR3: 000000012f290000 CR4: 00000000000006e0
Call Trace:
 free_debug_processing+0x1dd/0x240
 __slab_free+0x231/0x410
 kmem_cache_free+0x30e/0x360
 xchk_ag_btcur_free+0x76/0xb0
 xchk_ag_free+0x10/0x80
 xchk_bmap_iextent_xref.isra.14+0xd9/0x120
 xchk_bmap_iextent+0x187/0x210
 xchk_bmap+0x2e0/0x3b0
 xfs_scrub_metadata+0x2e7/0x500
 xfs_ioc_scrub_metadata+0x4a/0xa0
 xfs_file_ioctl+0x58a/0xcd0
 do_vfs_ioctl+0xa0/0x6f0
 ksys_ioctl+0x5b/0x90
 __x64_sys_ioctl+0x11/0x20
 do_syscall_64+0x4b/0x1a0
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

If preemption is disabled, all metadata buffers needed to perform the
scrub are already in memory, and there are a lot of records to check,
it's possible that the scrub thread will run for an extended period of
time without sleeping for IO or any other reason.  Then the watchdog
timer or the RCU stall timeout can trigger, producing the backtrace
above.

To fix this problem, call cond_resched() from the scrub thread so that
we back out to the scheduler whenever necessary.

Reported-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
2019-11-07 13:00:53 -08:00
..
agheader.c xfs: remove all *_ITER_ABORT values 2019-08-29 21:22:41 -07:00
agheader_repair.c xfs: remove unused header files 2019-06-28 19:30:43 -07:00
alloc.c xfs: removed unneeded variable 2019-09-23 13:00:56 -07:00
attr.c xfs: make attr lookup returns consistent 2019-08-30 22:43:57 -07:00
attr.h xfs: only allocate memory for scrubbing attributes when we need it 2019-07-05 10:29:56 -07:00
bitmap.c xfs: refactor xfs_iread_extents to use xfs_btree_visit_blocks 2019-10-29 09:50:12 -07:00
bitmap.h
bmap.c xfs: remove all *_ITER_ABORT values 2019-08-29 21:22:41 -07:00
btree.c xfs: remove unused header files 2019-06-28 19:30:43 -07:00
btree.h
common.c xfs: remove unused header files 2019-06-28 19:30:43 -07:00
common.h xfs: periodically yield scrub threads to the scheduler 2019-11-07 13:00:53 -08:00
dabtree.c xfs: Fix possible null-pointer dereferences in xchk_da_btree_block_check_sibling() 2019-07-30 11:28:20 -07:00
dabtree.h
dir.c xfs: add missing early termination checks to record scrubbing functions 2019-11-06 08:07:41 -08:00
fscounters.c xfs: add missing early termination checks to record scrubbing functions 2019-11-06 08:07:41 -08:00
health.c xfs: remove unused header files 2019-06-28 19:30:43 -07:00
health.h xfs: scrub should only cross-reference with healthy btrees 2019-04-16 10:01:57 -07:00
ialloc.c xfs: remove unused header files 2019-06-28 19:30:43 -07:00
inode.c xfs: remove unused header files 2019-06-28 19:30:43 -07:00
parent.c xfs: remove unused header files 2019-06-28 19:30:43 -07:00
quota.c xfs: add missing early termination checks to record scrubbing functions 2019-11-06 08:07:41 -08:00
refcount.c xfs: removed unused error variable from xchk_refcountbt_rec 2019-10-06 15:39:05 -07:00
repair.c xfs: remove all *_ITER_ABORT values 2019-08-29 21:22:41 -07:00
repair.h xfs: hoist the already_fixed variable to the scrub context 2019-04-16 10:01:57 -07:00
rmap.c xfs: remove unused header files 2019-06-28 19:30:43 -07:00
rtbitmap.c xfs: remove unused header files 2019-06-28 19:30:43 -07:00
scrub.c xfs: remove unused header files 2019-06-28 19:30:43 -07:00
scrub.h xfs: add online scrub for superblock counters 2019-04-30 08:19:13 -07:00
symlink.c fs: xfs: Remove KM_NOSLEEP and KM_SLEEP. 2019-08-26 12:06:22 -07:00
trace.c xfs: remove unused header files 2019-06-28 19:30:43 -07:00
trace.h xfs: add online scrub for superblock counters 2019-04-30 08:19:13 -07:00
xfs_scrub.h