kernel/block/blk-cgroup.c, branch linux-5.1.y

blkcg: update blkcg_print_stat() to handle larger outputs

2019-07-26T07:13:07Z

commit f539da82f2158916e154d206054e0efd5df7ab61 upstream. Depending on the number of devices, blkcg stats can go over the default seqfile buf size. seqfile normally retries with a larger buffer but since the ->pd_stat() addition, blkcg_print_stat() doesn't tell seqfile that overflow has happened and the output gets printed truncated. Fix it by calling seq_commit() w/ -1 on possible overflows. Signed-off-by: Tejun Heo Fixes: 903d23f0a354 ("blk-cgroup: allow controllers to output their own stats") Cc: stable@vger.kernel.org # v4.19+ Cc: Josef Bacik Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

blkcg: Fix kernel-doc warnings

2019-03-20T20:39:09Z

Avoid that the following warnings are reported when building with W=1: block/blk-cgroup.c:1755: warning: Function parameter or member 'q' not described in 'blkcg_schedule_throttle' block/blk-cgroup.c:1755: warning: Function parameter or member 'use_memdelay' not described in 'blkcg_schedule_throttle' block/blk-cgroup.c:1779: warning: Function parameter or member 'blkg' not described in 'blkcg_add_delay' block/blk-cgroup.c:1779: warning: Function parameter or member 'now' not described in 'blkcg_add_delay' block/blk-cgroup.c:1779: warning: Function parameter or member 'delta' not described in 'blkcg_add_delay' Signed-off-by: Bart Van Assche Signed-off-by: Jens Axboe

blk-cgroup: Fix doc related to blkcg_exit_queue

2019-02-10T15:24:08Z

Since 4cf6324b17e9, a portion of function blk_cleanup_queue was moved to a newly created function called blk_exit_queue, including the call of blkcg_exit_queue. So, adjust the documenation according. Reviewed-by: Bart Van Assche Signed-off-by: Marcos Paulo de Souza Signed-off-by: Jens Axboe

blkcg: remove unused __blkg_release_rcu()

2018-12-21T15:47:58Z

An earlier commit 7fcf2b033b84 ("blkcg: change blkg reference counting to use percpu_ref") moved around the release call from blkg_put() to be a part of the percpu_ref cleanup. Remove the additional unused code which should have been removed earlier. Signed-off-by: Dennis Zhou Signed-off-by: Jens Axboe

block: save irq state in blkg_lookup_create()

2018-12-19T16:35:45Z

blkg_lookup_create() may be called from pool_map() in which irq state is saved, so we have to do that in blkg_lookup_create(). Otherwise, the following lockdep warning can be triggered: [ 104.258537] ================================ [ 104.259129] WARNING: inconsistent lock state [ 104.259725] 4.20.0-rc6+ #545 Not tainted [ 104.260268] -------------------------------- [ 104.260865] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. [ 104.261727] swapper/49/0 [HC0[0]:SC1[1]:HE0:SE0] takes: [ 104.262444] 00000000db365b5d (&(&pool->lock)->rlock#3){+.?.}, at: thin_endio+0xcf/0x2a3 [dm_thin_pool] [ 104.263747] {SOFTIRQ-ON-W} state was registered at: [ 104.264417] _raw_spin_unlock_irq+0x29/0x4c [ 104.265014] blkg_lookup_create+0xdc/0xe6 [ 104.265609] bio_associate_blkg_from_css+0xd3/0x13f [ 104.266312] bio_associate_blkg+0x15a/0x1bb [ 104.266913] pool_map+0xe8/0x103 [dm_thin_pool] [ 104.267572] __map_bio+0x98/0x29c [dm_mod] [ 104.268162] __split_and_process_non_flush+0x29e/0x306 [dm_mod] [ 104.269003] __split_and_process_bio+0x16a/0x25b [dm_mod] [ 104.269971] __dm_make_request.isra.14+0xdc/0x124 [dm_mod] [ 104.270973] generic_make_request+0x3f5/0x68b [ 104.271676] process_prepared_mapping+0x166/0x1ef [dm_thin_pool] [ 104.272531] schedule_zero+0x239/0x273 [dm_thin_pool] [ 104.273245] process_cell+0x60c/0x6f1 [dm_thin_pool] [ 104.273967] do_worker+0x60c/0xca8 [dm_thin_pool] [ 104.274635] process_one_work+0x4eb/0x834 [ 104.275203] worker_thread+0x318/0x484 [ 104.275740] kthread+0x1d1/0x1e1 [ 104.276203] ret_from_fork+0x3a/0x50 [ 104.276714] irq event stamp: 170003 [ 104.277201] hardirqs last enabled at (170002): [] _raw_spin_unlock_irqrestore+0x44/0x6b [ 104.278535] hardirqs last disabled at (170003): [] _raw_spin_lock_irqsave+0x20/0x55 [ 104.280273] softirqs last enabled at (169978): [] irq_enter+0x4c/0x73 [ 104.281617] softirqs last disabled at (169979): [] irq_exit+0x7e/0x11d [ 104.282744] [ 104.282744] other info that might help us debug this: [ 104.283640] Possible unsafe locking scenario: [ 104.283640] [ 104.284452] CPU0 [ 104.284803] ---- [ 104.285150] lock(&(&pool->lock)->rlock#3); [ 104.285762] [ 104.286130] lock(&(&pool->lock)->rlock#3); [ 104.286750] [ 104.286750] *** DEADLOCK *** [ 104.286750] [ 104.287564] no locks held by swapper/49/0. [ 104.288129] [ 104.288129] stack backtrace: [ 104.288738] CPU: 49 PID: 0 Comm: swapper/49 Not tainted 4.20.0-rc6+ #545 [ 104.289700] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.10.2-2.fc27 04/01/2014 [ 104.290858] Call Trace: [ 104.291204] [ 104.291502] dump_stack+0x9a/0xe6 [ 104.291968] mark_lock+0x56c/0x7a6 [ 104.292442] ? check_usage_backwards+0x209/0x209 [ 104.293086] __lock_acquire+0x400/0x15bf [ 104.293662] ? check_chain_key+0x150/0x1aa [ 104.294236] lock_acquire+0x1a6/0x1e3 [ 104.294768] ? thin_endio+0xcf/0x2a3 [dm_thin_pool] [ 104.295444] ? _raw_spin_unlock_irqrestore+0x44/0x6b [ 104.296143] ? process_prepared_discard_fail+0x36/0x36 [dm_thin_pool] [ 104.297031] _raw_spin_lock_irqsave+0x46/0x55 [ 104.297659] ? thin_endio+0xcf/0x2a3 [dm_thin_pool] [ 104.298335] thin_endio+0xcf/0x2a3 [dm_thin_pool] [ 104.298997] ? process_prepared_discard_fail+0x36/0x36 [dm_thin_pool] [ 104.299886] ? check_flags+0x20a/0x20a [ 104.300408] ? lock_acquire+0x1a6/0x1e3 [ 104.300954] ? process_prepared_discard_fail+0x36/0x36 [dm_thin_pool] [ 104.301865] clone_endio+0x1bb/0x22d [dm_mod] [ 104.302491] ? disable_write_zeroes+0x20/0x20 [dm_mod] [ 104.303200] ? bio_disassociate_blkg+0xc6/0x15f [ 104.303836] ? bio_endio+0x2b2/0x2da [ 104.304349] clone_endio+0x1f3/0x22d [dm_mod] [ 104.304978] ? disable_write_zeroes+0x20/0x20 [dm_mod] [ 104.305709] ? bio_disassociate_blkg+0xc6/0x15f [ 104.306333] ? bio_endio+0x2b2/0x2da [ 104.306853] clone_endio+0x1f3/0x22d [dm_mod] [ 104.307476] ? disable_write_zeroes+0x20/0x20 [dm_mod] [ 104.308185] ? bio_disassociate_blkg+0xc6/0x15f [ 104.308817] ? bio_endio+0x2b2/0x2da [ 104.309319] blk_update_request+0x2de/0x4cc [ 104.309927] blk_mq_end_request+0x2a/0x183 [ 104.310498] blk_done_softirq+0x16a/0x1a6 [ 104.311051] ? blk_softirq_cpu_dead+0xe2/0xe2 [ 104.311653] ? __lock_is_held+0x2a/0x87 [ 104.312186] __do_softirq+0x250/0x4e8 [ 104.312705] irq_exit+0x7e/0x11d [ 104.313157] call_function_single_interrupt+0xf/0x20 [ 104.313860] [ 104.314163] RIP: 0010:native_safe_halt+0x2/0x3 [ 104.314792] Code: 63 02 df f0 83 44 24 fc 00 48 89 df e8 cc 3f 7a ff 48 8b 03 a8 08 74 0b 65 81 25 9d 31 45 7e ff ff ff 7f 5b 5d 41 5c c3 fb f4 f4 c3 0f 1f 44 00 00 41 56 41 55 41 54 55 53 e8 a2 0d 5c ff e8 [ 104.317339] RSP: 0018:ffff888106c9fdc0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff04 [ 104.318390] RAX: 1ffff11020d92100 RBX: 0000000000000000 RCX: ffffffff81159ac7 [ 104.319366] RDX: 1ffffffff05d5e69 RSI: 0000000000000007 RDI: ffff888106c90d1c [ 104.320339] RBP: 0000000000000000 R08: dffffc0000000000 R09: 0000000000000001 [ 104.321313] R10: ffffed1025d57ba0 R11: ffffed1025d57b9f R12: 1ffff11020d93fbf [ 104.322328] R13: 0000000000000031 R14: ffff888106c90040 R15: 0000000000000000 [ 104.323307] ? lockdep_hardirqs_on+0x26b/0x278 [ 104.323927] default_idle+0xd9/0x1a8 [ 104.324427] do_idle+0x162/0x2b2 [ 104.324891] ? arch_cpu_idle_exit+0x28/0x28 [ 104.325467] ? mark_held_locks+0x28/0x7f [ 104.326031] ? _raw_spin_unlock_irqrestore+0x44/0x6b [ 104.326719] cpu_startup_entry+0x1d/0x1f [ 104.327261] start_secondary+0x2cb/0x308 [ 104.327806] ? set_cpu_sibling_map+0x8a3/0x8a3 [ 104.328421] secondary_startup_64+0xa4/0xb0 Fixes: b978962ad4f7f9 ("blkcg: update blkg_lookup_create() to do locking") Cc: Mike Snitzer Cc: Dennis Zhou Signed-off-by: Ming Lei Signed-off-by: Jens Axboe

blkcg: handle dying request_queue when associating a blkg

2018-12-13T00:43:33Z

Between v3 [1] and v4 [2] of the blkg association series, the association point moved from generic_make_request_checks(), which is called after the request enters the queue, to bio_set_dev(), which is when the bio is formed before submit_bio(). When the request_queue goes away, the blkgs supporting the request_queue are destroyed and then the q->root_blkg is set to %NULL. This patch adds a %NULL check to blkg_tryget_closest() to prevent the NPE caused by the above. It also adds a guard to see if the request_queue is dying when creating a blkg to prevent creating a blkg for a dead request_queue. [1] https://lore.kernel.org/lkml/20180911184137.35897-1-dennisszhou@gmail.com/ [2] https://lore.kernel.org/lkml/20181126211946.77067-1-dennis@kernel.org/ Fixes: 5cdf2e3fea5e ("blkcg: associate blkg when associating a device") Reported-and-tested-by: Ming Lei Reviewed-by: Bart Van Assche Signed-off-by: Dennis Zhou Signed-off-by: Jens Axboe

blkcg: rename blkg_try_get() to blkg_tryget()

2018-12-08T05:26:38Z

blkg reference counting now uses percpu_ref rather than atomic_t. Let's make this consistent with css_tryget. This renames blkg_try_get to blkg_tryget and now returns a bool rather than the blkg or %NULL. Signed-off-by: Dennis Zhou Reviewed-by: Josef Bacik Acked-by: Tejun Heo Signed-off-by: Jens Axboe

blkcg: change blkg reference counting to use percpu_ref

2018-12-08T05:26:38Z

Every bio is now associated with a blkg putting blkg_get, blkg_try_get, and blkg_put on the hot path. Switch over the refcnt in blkg to use percpu_ref. Signed-off-by: Dennis Zhou Acked-by: Tejun Heo Reviewed-by: Josef Bacik Signed-off-by: Jens Axboe

blkcg: convert blkg_lookup_create() to find closest blkg

2018-12-08T05:26:36Z

There are several scenarios where blkg_lookup_create() can fail such as the blkcg dying, request_queue is dying, or simply being OOM. Most handle this by simply falling back to the q->root_blkg and calling it a day. This patch implements the notion of closest blkg. During blkg_lookup_create(), if it fails to create, return the closest blkg found or the q->root_blkg. blkg_try_get_closest() is introduced and used during association so a bio is always attached to a blkg. Signed-off-by: Dennis Zhou Acked-by: Tejun Heo Reviewed-by: Josef Bacik Signed-off-by: Jens Axboe

blkcg: update blkg_lookup_create() to do locking

2018-12-08T05:26:36Z

To know when to create a blkg, the general pattern is to do a blkg_lookup() and if that fails, lock and do the lookup again, and if that fails finally create. It doesn't make much sense for everyone who wants to do creation to write this themselves. This changes blkg_lookup_create() to do locking and implement this pattern. The old blkg_lookup_create() is renamed to __blkg_lookup_create(). If a call site wants to do its own error handling or already owns the queue lock, they can use __blkg_lookup_create(). This will be used in upcoming patches. Signed-off-by: Dennis Zhou Reviewed-by: Josef Bacik Acked-by: Tejun Heo Reviewed-by: Liu Bo Signed-off-by: Jens Axboe