Peter Zijlstra 18dd7b964c block/mq: Cure cpu hotplug lock inversion ... [ Upstream commit eabe06595d ] By poking at /debug/sched_features I triggered the following splat: [] ====================================================== [] WARNING: possible circular locking dependency detected [] 4.11.0-00873-g964c8b7-dirty #694 Not tainted [] ------------------------------------------------------ [] bash/2109 is trying to acquire lock: [] (cpu_hotplug_lock.rw_sem){++++++}, at: [<ffffffff8120cb8b>] static_key_slow_dec+0x1b/0x50 [] [] but task is already holding lock: [] (&sb->s_type->i_mutex_key#4){+++++.}, at: [<ffffffff81140216>] sched_feat_write+0x86/0x170 [] [] which lock already depends on the new lock. [] [] [] the existing dependency chain (in reverse order) is: [] [] -> #2 (&sb->s_type->i_mutex_key#4){+++++.}: [] lock_acquire+0x100/0x210 [] down_write+0x28/0x60 [] start_creating+0x5e/0xf0 [] debugfs_create_dir+0x13/0x110 [] blk_mq_debugfs_register+0x21/0x70 [] blk_mq_register_dev+0x64/0xd0 [] blk_register_queue+0x6a/0x170 [] device_add_disk+0x22d/0x440 [] loop_add+0x1f3/0x280 [] loop_init+0x104/0x142 [] do_one_initcall+0x43/0x180 [] kernel_init_freeable+0x1de/0x266 [] kernel_init+0xe/0x100 [] ret_from_fork+0x31/0x40 [] [] -> #1 (all_q_mutex){+.+.+.}: [] lock_acquire+0x100/0x210 [] __mutex_lock+0x6c/0x960 [] mutex_lock_nested+0x1b/0x20 [] blk_mq_init_allocated_queue+0x37c/0x4e0 [] blk_mq_init_queue+0x3a/0x60 [] loop_add+0xe5/0x280 [] loop_init+0x104/0x142 [] do_one_initcall+0x43/0x180 [] kernel_init_freeable+0x1de/0x266 [] kernel_init+0xe/0x100 [] ret_from_fork+0x31/0x40 [] *** DEADLOCK *** [] [] 3 locks held by bash/2109: [] #0: (sb_writers#11){.+.+.+}, at: [<ffffffff81292bcd>] vfs_write+0x17d/0x1a0 [] #1: (debugfs_srcu){......}, at: [<ffffffff8155a90d>] full_proxy_write+0x5d/0xd0 [] #2: (&sb->s_type->i_mutex_key#4){+++++.}, at: [<ffffffff81140216>] sched_feat_write+0x86/0x170 [] [] stack backtrace: [] CPU: 9 PID: 2109 Comm: bash Not tainted 4.11.0-00873-g964c8b7-dirty #694 [] Hardware name: Intel Corporation S2600GZ/S2600GZ, BIOS SE5C600.86B.02.02.0002.122320131210 12/23/2013 [] Call Trace: [] lock_acquire+0x100/0x210 [] get_online_cpus+0x2a/0x90 [] static_key_slow_dec+0x1b/0x50 [] static_key_disable+0x20/0x30 [] sched_feat_write+0x131/0x170 [] full_proxy_write+0x97/0xd0 [] __vfs_write+0x28/0x120 [] vfs_write+0xb5/0x1a0 [] SyS_write+0x49/0xa0 [] entry_SYSCALL_64_fastpath+0x23/0xc2 This is because of the cpu hotplug lock rework. Break the chain at #1 by reversing the lock acquisition order. This way i_mutex_key#4 no longer depends on cpu_hotplug_lock and things are good. Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2018-03-24 11:00:22 +01:00
..
partitions	partitions/efi: Fix integer overflow in GPT size calculation	2017-10-08 10:26:06 +02:00
badblocks.c	badblocks: fix wrong return value in badblocks_set if badblocks are disabled	2017-12-20 10:07:29 +01:00
bio-integrity.c	block: rename bio bi_rw to bi_opf	2016-08-07 14:41:02 -06:00
bio.c	bio_copy_user_iov(): don't ignore ->iov_offset	2017-10-18 09:35:41 +02:00
blk-cgroup.c	blkcg: fix double free of new_blkg in blkcg_init_queue	2018-03-22 09:17:35 +01:00
blk-core.c	block: wake up all tasks blocked in get_request()	2017-12-14 09:28:23 +01:00
blk-exec.c	block: Fix spelling in a source code comment	2016-07-20 21:28:22 -06:00
blk-flush.c	block: flush: fix IO hang in case of flood fua req	2016-10-26 07:49:27 -06:00
blk-integrity.c	block: fix blk_integrity_register to use template's interval_exp if not 0	2017-05-20 14:28:36 +02:00
blk-ioc.c	mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd	2015-11-06 17:50:42 -08:00
blk-lib.c	block: require write_same and discard requests align to logical block size	2016-10-11 15:06:30 -07:00
blk-map.c	blk_rq_map_user_iov: fix error override	2018-02-25 11:05:42 +01:00
blk-merge.c	block: make sure a big bio is split into at most 256 bvecs	2016-08-24 08:17:24 -06:00
blk-mq-cpumap.c	blk-mq: allow the driver to pass in a queue mapping	2016-09-15 08:42:03 -06:00
blk-mq-pci.c	blk-mq-pci: add a fallback when pci_irq_get_affinity returns NULL	2017-08-24 17:12:20 -07:00
blk-mq-sysfs.c	blk-mq: initialize mq kobjects in blk_mq_init_allocated_queue()	2017-12-14 09:28:21 +01:00
blk-mq-tag.c	blk-mq: Fix tagset reinit in the presence of cpu hot-unplug	2017-12-20 10:07:20 +01:00
blk-mq-tag.h	Merge branch 'for-4.9/block-irq' of git://git.kernel.dk/linux-block	2016-10-09 17:29:33 -07:00
blk-mq.c	block/mq: Cure cpu hotplug lock inversion	2018-03-24 11:00:22 +01:00
blk-mq.h	blk-mq: initialize mq kobjects in blk_mq_init_allocated_queue()	2017-12-14 09:28:21 +01:00
blk-settings.c	block: kill off q->flush_flags	2016-04-13 13:33:19 -06:00
blk-softirq.c	This adds a new gcc plugin named "latent_entropy". It is designed to	2016-10-15 10:03:15 -07:00
blk-sysfs.c	blk-mq: register device instead of disk	2016-09-21 07:56:16 -06:00
blk-tag.c	block: support different tag allocation policy	2015-01-23 14:15:46 -07:00
blk-throttle.c	blk-throttle: make sure expire time isn't too big	2018-03-22 09:17:44 +01:00
blk-timeout.c	block: Fix a race between blk_cleanup_queue() and timeout handling	2017-11-30 08:39:06 +00:00
blk.h	blk-mq: remove ->map_queue	2016-09-15 08:42:03 -06:00
bounce.c	Merge branch 'for-linus' of git://git.kernel.dk/linux-block	2015-09-19 18:57:09 -07:00
bsg-lib.c	Revert "bsg-lib: don't free job in bsg_prepare_job"	2017-10-21 17:21:33 +02:00
bsg.c	sg_write()/bsg_write() is not fit to be called under KERNEL_DS	2017-01-09 08:32:25 +01:00
cfq-iosched.c	cfq-iosched: fix the delay of cfq_group's vdisktime under iops mode	2017-06-14 15:05:58 +02:00
cmdline-parser.c	block: remove unrelated header files and export symbol	2014-01-21 20:18:26 -08:00
compat_ioctl.c	mm, fs: get rid of PAGE_CACHE_* and page_cache_{get,release} macros	2016-04-04 10:41:08 -07:00
deadline-iosched.c	block: do not merge requests without consulting with io scheduler	2016-07-20 21:35:12 -06:00
elevator.c	block: Fix secure erase	2016-08-16 09:16:51 -06:00
genhd.c	block: fix bdi vs gendisk lifetime mismatch	2016-08-04 14:19:16 -06:00
ioctl.c	block: invalidate the page cache when issuing BLKZEROOUT	2016-10-11 15:06:30 -07:00
ioprio.c	block: fix use-after-free in sys_ioprio_get()	2016-07-01 08:39:24 -06:00
Kconfig	Merge branch 'for-4.9/block-irq' of git://git.kernel.dk/linux-block	2016-10-09 17:29:33 -07:00
Kconfig.iosched	blkcg: make CONFIG_BLK_CGROUP bool	2012-03-06 21:27:21 +01:00
Makefile	Merge branch 'for-4.9/block-smp' of git://git.kernel.dk/linux-block	2016-10-09 17:32:20 -07:00
noop-iosched.c	elevator: use list_{first,prev,next}_entry	2015-11-16 15:21:48 -07:00
partition-generic.c	block: get rid of blk_integrity_revalidate()	2017-05-14 14:00:22 +02:00
scsi_ioctl.c	block: allow WRITE_SAME commands with the SG_IO ioctl	2017-03-22 12:43:38 +01:00
t10-pi.c	block: Consolidate static integrity profile properties	2015-10-21 14:42:38 -06:00