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ecb2ba8cb8
linux/drivers/md/bcache
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Coly Li ecb2ba8cb8 bcache: add wait_for_kthread_stop() in bch_allocator_thread() 
When CACHE_SET_IO_DISABLE is set on cache set flags, bcache allocator
thread routine bch_allocator_thread() may stop the while-loops and
exit. Then it is possible to observe the following kernel oops message,

[  631.068366] bcache: bch_btree_insert() error -5
[  631.069115] bcache: cached_dev_detach_finish() Caching disabled for sdf
[  631.070220] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
[  631.070250] PGD 0 P4D 0
[  631.070261] Oops: 0002 [#1] SMP PTI
[snipped]
[  631.070578] Workqueue: events cache_set_flush [bcache]
[  631.070597] RIP: 0010:exit_creds+0x1b/0x50
[  631.070610] RSP: 0018:ffffc9000705fe08 EFLAGS: 00010246
[  631.070626] RAX: 0000000000000001 RBX: ffff880a622ad300 RCX: 000000000000000b
[  631.070645] RDX: 0000000000000601 RSI: 000000000000000c RDI: 0000000000000000
[  631.070663] RBP: ffff880a622ad300 R08: ffffea00190c66e0 R09: 0000000000000200
[  631.070682] R10: ffff880a48123000 R11: ffff880000000000 R12: 0000000000000000
[  631.070700] R13: ffff880a4b160e40 R14: ffff880a4b160000 R15: 0ffff880667e2530
[  631.070719] FS:  0000000000000000(0000) GS:ffff880667e00000(0000) knlGS:0000000000000000
[  631.070740] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  631.070755] CR2: 0000000000000000 CR3: 000000000200a001 CR4: 00000000003606e0
[  631.070774] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  631.070793] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  631.070811] Call Trace:
[  631.070828]  __put_task_struct+0x55/0x160
[  631.070845]  kthread_stop+0xee/0x100
[  631.070863]  cache_set_flush+0x11d/0x1a0 [bcache]
[  631.070879]  process_one_work+0x146/0x340
[  631.070892]  worker_thread+0x47/0x3e0
[  631.070906]  kthread+0xf5/0x130
[  631.070917]  ? max_active_store+0x60/0x60
[  631.070930]  ? kthread_bind+0x10/0x10
[  631.070945]  ret_from_fork+0x35/0x40
[snipped]
[  631.071017] RIP: exit_creds+0x1b/0x50 RSP: ffffc9000705fe08
[  631.071033] CR2: 0000000000000000
[  631.071045] ---[ end trace 011c63a24b22c927 ]---
[  631.071085] bcache: bcache_device_free() bcache0 stopped

The reason is when cache_set_flush() tries to call kthread_stop() to stop
allocator thread, but it exits already due to cache device I/O errors.

This patch adds wait_for_kthread_stop() at tail of bch_allocator_thread(),
to prevent the thread routine exiting directly. Then the allocator thread
can be blocked at wait_for_kthread_stop() and wait for cache_set_flush()
to stop it by calling kthread_stop().

changelog:
v3: add Reviewed-by from Hannnes.
v2: not directly return from allocator_wait(), move 'return 0' to tail of
    bch_allocator_thread().
v1: initial version.

Fixes: 771f393e8f ("bcache: add CACHE_SET_IO_DISABLE to struct cache_set flags")
Signed-off-by: Coly Li <colyli@suse.de>
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-03 08:35:13 -06:00
..
alloc.c bcache: add wait_for_kthread_stop() in bch_allocator_thread() 2018-05-03 08:35:13 -06:00
bcache.h bcache: store disk name in struct cache and struct cached_dev 2018-05-03 08:35:08 -06:00
bset.c bcache: Suppress more warnings about set-but-not-used variables 2018-03-18 20:15:20 -06:00
bset.h bcache: Add __printf annotation to __bch_check_keys() 2018-03-18 20:15:20 -06:00
btree.c bcache: Fix kernel-doc warnings 2018-03-18 20:15:20 -06:00
btree.h Merge branch 'for-4.15/block' of git://git.kernel.dk/linux-block 2017-11-14 15:32:19 -08:00
closure.c bcache: Fix kernel-doc warnings 2018-03-18 20:15:20 -06:00
closure.h bcache: move closure debug file into debug directory 2018-03-18 20:15:20 -06:00
debug.c bcache: store disk name in struct cache and struct cached_dev 2018-05-03 08:35:08 -06:00
debug.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
extents.c bcache: Remove an unused variable 2018-03-18 20:15:20 -06:00
extents.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
io.c bcache: store disk name in struct cache and struct cached_dev 2018-05-03 08:35:08 -06:00
journal.c bcache: Reduce the number of sparse complaints about lock imbalances 2018-03-18 20:15:20 -06:00
journal.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig bcache: Kill dead cgroup code 2014-03-18 12:22:35 -07:00
Makefile License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
movinggc.c block: move bio_alloc_pages() to bcache 2018-01-06 09:18:00 -07:00
request.c bcache: store disk name in struct cache and struct cached_dev 2018-05-03 08:35:08 -06:00
request.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
stats.c md: Convert timers to use timer_setup() 2017-11-14 20:11:57 -07:00
stats.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
super.c bcache: set CACHE_SET_IO_DISABLE in bch_cached_dev_error() 2018-05-03 08:35:10 -06:00
sysfs.c bcache: add io_disable to struct cached_dev 2018-03-18 20:15:20 -06:00
sysfs.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
trace.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
util.c bcache: Fix kernel-doc warnings 2018-03-18 20:15:20 -06:00
util.h bcache: add CACHE_SET_IO_DISABLE to struct cache_set flags 2018-03-18 20:15:20 -06:00
writeback.c bcache: count backing device I/O error for writeback I/O 2018-05-03 08:35:12 -06:00
writeback.h bcache: Fix indentation 2018-03-18 20:15:20 -06:00