Commit Graph

79 Commits

Author SHA1 Message Date
Yu Kuai 671fae5e51 blk-wbt: don't enable throttling if default elevator is bfq
Commit b5dc5d4d1f ("block,bfq: Disable writeback throttling") tries to
disable wbt for bfq, it's done by calling wbt_disable_default() in
bfq_init_queue(). However, wbt is still enabled if default elevator is
bfq:

device_add_disk
 elevator_init_mq
  bfq_init_queue
   wbt_disable_default -> done nothing

 blk_register_queue
  wbt_enable_default -> wbt is enabled

Fix the problem by adding a new flag ELEVATOR_FLAG_DISBALE_WBT, bfq
will set the flag in bfq_init_queue, and following wbt_enable_default()
won't enable wbt while the flag is set.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20221019121518.3865235-7-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-10-23 18:59:17 -06:00
Yu Kuai 3642ef4d95 blk-wbt: don't show valid wbt_lat_usec in sysfs while wbt is disabled
Currently, if wbt is initialized and then disabled by
wbt_disable_default(), sysfs will still show valid wbt_lat_usec, which
will confuse users that wbt is still enabled.

This patch shows wbt_lat_usec as zero if it's disabled.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reported-and-tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20221019121518.3865235-5-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-10-23 18:59:17 -06:00
Yu Kuai a9a236d238 blk-wbt: make enable_state more accurate
Currently, if user disable wbt through sysfs, 'enable_state' will be
'WBT_STATE_ON_MANUAL', which will be confusing. Add a new state
'WBT_STATE_OFF_MANUAL' to cover that case.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20221019121518.3865235-4-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-10-23 18:59:17 -06:00
Yu Kuai b11d31ae01 blk-wbt: remove unnecessary check in wbt_enable_default()
If CONFIG_BLK_WBT_MQ is disabled, wbt_init() won't do anything.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20221019121518.3865235-3-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-10-23 18:59:17 -06:00
Yu Kuai 285febabac blk-wbt: fix that 'rwb->wc' is always set to 1 in wbt_init()
commit 8c5035dfbb ("blk-wbt: call rq_qos_add() after wb_normal is
initialized") moves wbt_set_write_cache() before rq_qos_add(), which
is wrong because wbt_rq_qos() is still NULL.

Fix the problem by removing wbt_set_write_cache() and setting 'rwb->wc'
directly. Noted that this patch also remove the redundant setting of
'rab->wc'.

Fixes: 8c5035dfbb ("blk-wbt: call rq_qos_add() after wb_normal is initialized")
Reported-by: kernel test robot <yujie.liu@intel.com>
Link: https://lore.kernel.org/r/202210081045.77ddf59b-yujie.liu@intel.com
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20221009101038.1692875-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-10-09 07:48:16 -06:00
Yu Kuai 8c5035dfbb blk-wbt: call rq_qos_add() after wb_normal is initialized
Our test found a problem that wbt inflight counter is negative, which
will cause io hang(noted that this problem doesn't exist in mainline):

t1: device create	t2: issue io
add_disk
 blk_register_queue
  wbt_enable_default
   wbt_init
    rq_qos_add
    // wb_normal is still 0
			/*
			 * in mainline, disk can't be opened before
			 * bdev_add(), however, in old kernels, disk
			 * can be opened before blk_register_queue().
			 */
			blkdev_issue_flush
                        // disk size is 0, however, it's not checked
                         submit_bio_wait
                          submit_bio
                           blk_mq_submit_bio
                            rq_qos_throttle
                             wbt_wait
			      bio_to_wbt_flags
                               rwb_enabled
			       // wb_normal is 0, inflight is not increased

    wbt_queue_depth_changed(&rwb->rqos);
     wbt_update_limits
     // wb_normal is initialized
                            rq_qos_track
                             wbt_track
                              rq->wbt_flags |= bio_to_wbt_flags(rwb, bio);
			      // wb_normal is not 0,wbt_flags will be set
t3: io completion
blk_mq_free_request
 rq_qos_done
  wbt_done
   wbt_is_tracked
   // return true
   __wbt_done
    wbt_rqw_done
     atomic_dec_return(&rqw->inflight);
     // inflight is decreased

commit 8235b5c1e8 ("block: call bdev_add later in device_add_disk") can
avoid this problem, however it's better to fix this problem in wbt:

1) Lower kernel can't backport this patch due to lots of refactor.
2) Root cause is that wbt call rq_qos_add() before wb_normal is
initialized.

Fixes: e34cbd3074 ("blk-wbt: add general throttling mechanism")
Cc: <stable@vger.kernel.org>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20220913105749.3086243-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-09-21 08:36:13 -06:00
Jinke Han 14a6e2eb7d block: don't allow the same type rq_qos add more than once
In our test of iocost, we encountered some list add/del corruptions of
inner_walk list in ioc_timer_fn.

The reason can be described as follows:

cpu 0					cpu 1
ioc_qos_write				ioc_qos_write

ioc = q_to_ioc(queue);
if (!ioc) {
        ioc = kzalloc();
					ioc = q_to_ioc(queue);
					if (!ioc) {
						ioc = kzalloc();
						...
						rq_qos_add(q, rqos);
					}
        ...
        rq_qos_add(q, rqos);
        ...
}

When the io.cost.qos file is written by two cpus concurrently, rq_qos may
be added to one disk twice. In that case, there will be two iocs enabled
and running on one disk. They own different iocgs on their active list. In
the ioc_timer_fn function, because of the iocgs from two iocs have the
same root iocg, the root iocg's walk_list may be overwritten by each other
and this leads to list add/del corruptions in building or destroying the
inner_walk list.

And so far, the blk-rq-qos framework works in case that one instance for
one type rq_qos per queue by default. This patch make this explicit and
also fix the crash above.

Signed-off-by: Jinke Han <hanjinke.666@bytedance.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20220720093616.70584-1-hanjinke.666@bytedance.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-20 06:44:14 -06:00
Bart Van Assche 16458cf3bd block: Use the new blk_opf_t type
Use the new blk_opf_t type for arguments and variables that represent
request flags or a bitwise combination of a request operation and
request flags. Rename the function arguments and also a structure member
that hold a request operation and flags from 'rw' into 'opf'.

This patch does not change any functionality.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20220714180729.1065367-7-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-14 12:14:30 -06:00
Bart Van Assche 77e7ffd7ad block: Use enum req_op where appropriate
Change the type of the arguments that are used to pass a REQ_OP_* value
from int or unsigned int into enum req_op to improve static type
checking.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Damien Le Moal <damien.lemoal@wdc.com>
Cc: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20220714180729.1065367-3-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2022-07-14 12:14:30 -06:00
Andrea Righi 480d42dc00 blk-wbt: prevent NULL pointer dereference in wb_timer_fn
The timer callback used to evaluate if the latency is exceeded can be
executed after the corresponding disk has been released, causing the
following NULL pointer dereference:

[ 119.987108] BUG: kernel NULL pointer dereference, address: 0000000000000098
[ 119.987617] #PF: supervisor read access in kernel mode
[ 119.987971] #PF: error_code(0x0000) - not-present page
[ 119.988325] PGD 7c4a4067 P4D 7c4a4067 PUD 7bf63067 PMD 0
[ 119.988697] Oops: 0000 [#1] SMP NOPTI
[ 119.988959] CPU: 1 PID: 9353 Comm: cloud-init Not tainted 5.15-rc5+arighi #rc5+arighi
[ 119.989520] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
[ 119.990055] RIP: 0010:wb_timer_fn+0x44/0x3c0
[ 119.990376] Code: 41 8b 9c 24 98 00 00 00 41 8b 94 24 b8 00 00 00 41 8b 84 24 d8 00 00 00 4d 8b 74 24 28 01 d3 01 c3 49 8b 44 24 60 48 8b 40 78 <4c> 8b b8 98 00 00 00 4d 85 f6 0f 84 c4 00 00 00 49 83 7c 24 30 00
[ 119.991578] RSP: 0000:ffffb5f580957da8 EFLAGS: 00010246
[ 119.991937] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000004
[ 119.992412] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88f476d7f780
[ 119.992895] RBP: ffffb5f580957dd0 R08: 0000000000000000 R09: 0000000000000000
[ 119.993371] R10: 0000000000000004 R11: 0000000000000002 R12: ffff88f476c84500
[ 119.993847] R13: ffff88f4434390c0 R14: 0000000000000000 R15: ffff88f4bdc98c00
[ 119.994323] FS: 00007fb90bcd9c00(0000) GS:ffff88f4bdc80000(0000) knlGS:0000000000000000
[ 119.994952] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 119.995380] CR2: 0000000000000098 CR3: 000000007c0d6000 CR4: 00000000000006e0
[ 119.995906] Call Trace:
[ 119.996130] ? blk_stat_free_callback_rcu+0x30/0x30
[ 119.996505] blk_stat_timer_fn+0x138/0x140
[ 119.996830] call_timer_fn+0x2b/0x100
[ 119.997136] __run_timers.part.0+0x1d1/0x240
[ 119.997470] ? kvm_clock_get_cycles+0x11/0x20
[ 119.997826] ? ktime_get+0x3e/0xa0
[ 119.998110] ? native_apic_msr_write+0x2c/0x30
[ 119.998456] ? lapic_next_event+0x20/0x30
[ 119.998779] ? clockevents_program_event+0x94/0xf0
[ 119.999150] run_timer_softirq+0x2a/0x50
[ 119.999465] __do_softirq+0xcb/0x26f
[ 119.999764] irq_exit_rcu+0x8c/0xb0
[ 120.000057] sysvec_apic_timer_interrupt+0x43/0x90
[ 120.000429] ? asm_sysvec_apic_timer_interrupt+0xa/0x20
[ 120.000836] asm_sysvec_apic_timer_interrupt+0x12/0x20

In this case simply return from the timer callback (no action
required) to prevent the NULL pointer dereference.

BugLink: https://bugs.launchpad.net/bugs/1947557
Link: https://lore.kernel.org/linux-mm/YWRNVTk9N8K0RMst@arighi-desktop/
Fixes: 34dbad5d26 ("blk-stat: convert to callback-based statistics reporting")
Signed-off-by: Andrea Righi <andrea.righi@canonical.com>
Link: https://lore.kernel.org/r/YW6N2qXpBU3oc50q@arighi-desktop
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-10-19 06:13:41 -06:00
Christoph Hellwig d152c682f0 block: add an explicit ->disk backpointer to the request_queue
Replace the magic lookup through the kobject tree with an explicit
backpointer, given that the device model links are set up and torn
down at times when I/O is still possible, leading to potential
NULL or invalid pointer dereferences.

Fixes: edb0872f44 ("block: move the bdi from the request_queue to the gendisk")
Reported-by: syzbot <syzbot+aa0801b6b32dca9dda82@syzkaller.appspotmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Tested-by: Sven Schnelle <svens@linux.ibm.com>
Link: https://lore.kernel.org/r/20210816134624.GA24234@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-23 12:54:31 -06:00
Christoph Hellwig edb0872f44 block: move the bdi from the request_queue to the gendisk
The backing device information only makes sense for file system I/O,
and thus belongs into the gendisk and not the lower level request_queue
structure.  Move it there.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20210809141744.1203023-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-08-09 11:53:23 -06:00
Zhang Yi 76a8040817 blk-wbt: make sure throttle is enabled properly
After commit a79050434b ("blk-rq-qos: refactor out common elements of
blk-wbt"), if throttle was disabled by wbt_disable_default(), we could
not enable again, fix this by set enable_state back to
WBT_STATE_ON_DEFAULT.

Fixes: a79050434b ("blk-rq-qos: refactor out common elements of blk-wbt")
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://lore.kernel.org/r/20210619093700.920393-3-yi.zhang@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-21 15:03:41 -06:00
Zhang Yi 1d0903d61e blk-wbt: introduce a new disable state to prevent false positive by rwb_enabled()
Now that we disable wbt by simply zero out rwb->wb_normal in
wbt_disable_default() when switch elevator to bfq, but it's not safe
because it will become false positive if we change queue depth. If it
become false positive between wbt_wait() and wbt_track() when submit
write request, it will lead to drop rqw->inflight to -1 in wbt_done(),
which will end up trigger IO hung. Fix this issue by introduce a new
state which mean the wbt was disabled.

Fixes: a79050434b ("blk-rq-qos: refactor out common elements of blk-wbt")
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Link: https://lore.kernel.org/r/20210619093700.920393-2-yi.zhang@huawei.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-21 15:03:41 -06:00
lijiazi a79da21b48 blk-wbt: remove outdated comment
Now wbt_wait() returns void, so remove now outdated comment.

Signed-off-by: lijiazi <lijiazi@xiaomi.com>
Link: https://lore.kernel.org/r/1623986240-13878-1-git-send-email-lijiazi@xiaomi.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-06-18 10:45:33 -06:00
Lei Chen 482e302a61 blk: wbt: remove unused parameter from wbt_should_throttle
The first parameter rwb is not used for this function.
So just remove it.

Signed-off-by: Lei Chen <lennychen@tencent.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-26 13:13:00 -07:00
Lei Chen 5a20d073ec block: wbt: Remove unnecessary invoking of wbt_update_limits in wbt_init
It's unnecessary to call wbt_update_limits explicitly within wbt_init,
because it will be called in the following function wbt_queue_depth_changed.

Signed-off-by: Lei Chen <lennychen@tencent.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-11-30 15:01:18 -07:00
Gustavo A. R. Silva df561f6688 treewide: Use fallthrough pseudo-keyword
Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
2020-08-23 17:36:59 -05:00
Guoqing Jiang 4d89e1d112 blk-wbt: rename __wbt_update_limits to wbt_update_limits
Now let's rename __wbt_update_limits to wbt_update_limits after the
previous one is deleted.

Signed-off-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-05-29 16:30:39 -06:00
Guoqing Jiang 26e0ca12e0 blk-wbt: remove wbt_update_limits
No one call this function after commit 2af2783f2e ("rq-qos: get rid of
redundant wbt_update_limits()"), so remove it.

Signed-off-by: Guoqing Jiang <guoqing.jiang@cloud.ionos.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-05-29 16:30:39 -06:00
Tommi Rantala 3a89c25d98 blk-wbt: Use tracepoint_string() for wbt_step tracepoint string literals
Use tracepoint_string() for string literals that are used in the
wbt_step tracepoint, so that userspace tools can display the string
content.

Signed-off-by: Tommi Rantala <tommi.t.rantala@nokia.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-04-17 08:21:44 -06:00
Harshad Shirwadkar b84477d3eb blk-wbt: fix performance regression in wbt scale_up/scale_down
scale_up wakes up waiters after scaling up. But after scaling max, it
should not wake up more waiters as waiters will not have anything to
do. This patch fixes this by making scale_up (and also scale_down)
return when threshold is reached.

This bug causes increased fdatasync latency when fdatasync and dd
conv=sync are performed in parallel on 4.19 compared to 4.14. This
bug was introduced during refactoring of blk-wbt code.

Fixes: a79050434b ("blk-rq-qos: refactor out common elements of blk-wbt")
Cc: stable@vger.kernel.org
Cc: Josef Bacik <jbacik@fb.com>
Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-10-06 09:26:41 -06:00
Tejun Heo 9677a3e01f block/rq_qos: implement rq_qos_ops->queue_depth_changed()
wbt already gets queue depth changed notification through
wbt_set_queue_depth().  Generalize it into
rq_qos_ops->queue_depth_changed() so that other rq_qos policies can
easily hook into the events too.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-08-28 21:17:07 -06:00
Ming Lei 58c898ba37 block: add helper for checking if queue is registered
There are 4 users which check if queue is registered, so add one helper
to check it.

Cc: Christoph Hellwig <hch@infradead.org>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-08-27 10:40:20 -06:00
Christoph Hellwig 3dcf60bcb6 block: add SPDX tags to block layer files missing licensing information
Various block layer files do not have any licensing information at all.
Add SPDX tags for the default kernel GPLv2 license to those.

Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-04-30 16:12:03 -06:00
Bart Van Assche c83f536a87 blk-wbt: Declare local functions static
This patch avoids that sparse reports the following warnings:

  CHECK   block/blk-wbt.c
block/blk-wbt.c:600:6: warning: symbol 'wbt_issue' was not declared. Should it be static?
block/blk-wbt.c:620:6: warning: symbol 'wbt_requeue' was not declared. Should it be static?
  CC      block/blk-wbt.o
block/blk-wbt.c:600:6: warning: no previous prototype for wbt_issue [-Wmissing-prototypes]
 void wbt_issue(struct rq_qos *rqos, struct request *rq)
      ^~~~~~~~~
block/blk-wbt.c:620:6: warning: no previous prototype for wbt_requeue [-Wmissing-prototypes]
 void wbt_requeue(struct rq_qos *rqos, struct request *rq)
      ^~~~~~~~~~~

Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-01-24 11:09:21 -07:00
Ming Lei d19afebca4 blk-wbt: export internal state via debugfs
This information is helpful to either investigate issues, or understand
wbt's internal behaviour.

Cc: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-16 19:53:49 -07:00
Ming Lei 544fbd16a4 block: deactivate blk_stat timer in wbt_disable_default()
rwb_enabled() can't be changed when there is any inflight IO.

wbt_disable_default() may set rwb->wb_normal as zero, however the
blk_stat timer may still be pending, and the timer function will update
wrb->wb_normal again.

This patch introduces blk_stat_deactivate() and applies it in
wbt_disable_default(), then the following IO hang triggered when running
parted & switching io scheduler can be fixed:

[  369.937806] INFO: task parted:3645 blocked for more than 120 seconds.
[  369.938941]       Not tainted 4.20.0-rc6-00284-g906c801e5248 #498
[  369.939797] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  369.940768] parted          D    0  3645   3239 0x00000000
[  369.941500] Call Trace:
[  369.941874]  ? __schedule+0x6d9/0x74c
[  369.942392]  ? wbt_done+0x5e/0x5e
[  369.942864]  ? wbt_cleanup_cb+0x16/0x16
[  369.943404]  ? wbt_done+0x5e/0x5e
[  369.943874]  schedule+0x67/0x78
[  369.944298]  io_schedule+0x12/0x33
[  369.944771]  rq_qos_wait+0xb5/0x119
[  369.945193]  ? karma_partition+0x1c2/0x1c2
[  369.945691]  ? wbt_cleanup_cb+0x16/0x16
[  369.946151]  wbt_wait+0x85/0xb6
[  369.946540]  __rq_qos_throttle+0x23/0x2f
[  369.947014]  blk_mq_make_request+0xe6/0x40a
[  369.947518]  generic_make_request+0x192/0x2fe
[  369.948042]  ? submit_bio+0x103/0x11f
[  369.948486]  ? __radix_tree_lookup+0x35/0xb5
[  369.949011]  submit_bio+0x103/0x11f
[  369.949436]  ? blkg_lookup_slowpath+0x25/0x44
[  369.949962]  submit_bio_wait+0x53/0x7f
[  369.950469]  blkdev_issue_flush+0x8a/0xae
[  369.951032]  blkdev_fsync+0x2f/0x3a
[  369.951502]  do_fsync+0x2e/0x47
[  369.951887]  __x64_sys_fsync+0x10/0x13
[  369.952374]  do_syscall_64+0x89/0x149
[  369.952819]  entry_SYSCALL_64_after_hwframe+0x49/0xbe
[  369.953492] RIP: 0033:0x7f95a1e729d4
[  369.953996] Code: Bad RIP value.
[  369.954456] RSP: 002b:00007ffdb570dd48 EFLAGS: 00000246 ORIG_RAX: 000000000000004a
[  369.955506] RAX: ffffffffffffffda RBX: 000055c2139c6be0 RCX: 00007f95a1e729d4
[  369.956389] RDX: 0000000000000001 RSI: 0000000000001261 RDI: 0000000000000004
[  369.957325] RBP: 0000000000000002 R08: 0000000000000000 R09: 000055c2139c6ce0
[  369.958199] R10: 0000000000000000 R11: 0000000000000246 R12: 000055c2139c0380
[  369.959143] R13: 0000000000000004 R14: 0000000000000100 R15: 0000000000000008

Cc: stable@vger.kernel.org
Cc: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-12 06:47:51 -07:00
Josef Bacik b6c7b58f5f block: convert wbt_wait() to use rq_qos_wait()
Now that we have rq_qos_wait() in place, convert wbt_wait() over to
using it with it's specific callbacks.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-12-07 22:26:38 -07:00
Jens Axboe 344e9ffcbd block: add queue_is_mq() helper
Various spots check for q->mq_ops being non-NULL, but provide
a helper to do this instead.

Where the ->mq_ops != NULL check is redundant, remove it.

Since mq == rq-based now that legacy is gone, get rid of the
queue_is_rq_based() and just use queue_is_mq() everywhere.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-16 08:34:06 -07:00
Jens Axboe e815f404af block: add wbt_disable_default export for BFQ
This isn't unused, if BFQ is modular we get into trouble.

Fixes: b6676f653f ("block: remove a few unused exports")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-15 12:31:27 -07:00
Christoph Hellwig b6676f653f block: remove a few unused exports
Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-15 12:13:25 -07:00
Christoph Hellwig d53375608e block: remove the unused lock argument to rq_qos_throttle
Unused now that the legacy request path is gone.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-15 12:13:22 -07:00
Jens Axboe 3c7741567b blk-wbt: kill check for legacy queue type
Everything is blk-mq at this point, so it doesn't make any sense
to have this option available as it does nothing.

Reviewed-by: Hannes Reinecke <hare@suse.com>
Tested-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-07 13:42:32 -07:00
Josef Bacik 5e65a20341 blk-wbt: wake up all when we scale up, not down
Tetsuo brought to my attention that I screwed up the scale_up/scale_down
helpers when I factored out the rq-qos code.  We need to wake up all the
waiters when we add slots for requests to make, not when we shrink the
slots.  Otherwise we'll end up things waiting forever.  This was a
mistake and simply puts everything back the way it was.

cc: stable@vger.kernel.org
Fixes: a79050434b ("blk-rq-qos: refactor out common elements of blk-wbt")
eported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-10-11 13:31:28 -06:00
Jens Axboe b0a84beb2e blk-wbt: remove dead code
We already note and mark discard and swap IO from bio_to_wbt_flags().

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-27 13:32:12 -06:00
Jens Axboe 38cfb5a45e blk-wbt: improve waking of tasks
We have two potential issues:

1) After commit 2887e41b91, we only wake one process at the time when
   we finish an IO. We really want to wake up as many tasks as can
   queue IO. Before this commit, we woke up everyone, which could cause
   a thundering herd issue.

2) A task can potentially consume two wakeups, causing us to (in
   practice) miss a wakeup.

Fix both by providing our own wakeup function, which stops
__wake_up_common() from waking up more tasks if we fail to get a
queueing token. With the strict ordering we have on the wait list, this
wakes the right tasks and the right amount of tasks.

Based on a patch from Jianchao Wang <jianchao.w.wang@oracle.com>.

Tested-by: Agarwal, Anchal <anchalag@amazon.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-27 11:27:26 -06:00
Jens Axboe 061a542753 blk-wbt: abstract out end IO completion handler
Prep patch for calling the handler from a different context,
no functional changes in this patch.

Tested-by: Agarwal, Anchal <anchalag@amazon.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-27 11:27:24 -06:00
Jens Axboe c125311d96 blk-wbt: don't maintain inflight counts if disabled
A previous commit removed the ability to have per-rq flags. We used
those flags to maintain inflight counts. Since we don't have those
anymore, we have to always maintain inflight counts, even if wbt is
disabled. This is clearly suboptimal.

Add a queue quiesce around changing the wbt latency settings from sysfs
to work around this. With that, we can reliably put the enabled check in
our bio_to_wbt_flags(), since we know the WBT_TRACKED flag will be
consistent for the lifetime of the request.

Fixes: c1c80384c8 ("block: remove external dependency on wbt_flags")
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-23 09:34:46 -06:00
Jens Axboe c45e6a037a blk-wbt: fix has-sleeper queueing check
We need to do this inside the loop as well, or we can allow new
IO to supersede previous IO.

Tested-by: Anchal Agarwal <anchalag@amazon.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-22 15:07:32 -06:00
Jens Axboe b78820937b blk-wbt: use wq_has_sleeper() for wq active check
We need the memory barrier before checking the list head,
use the appropriate helper for this. The matching queue
side memory barrier is provided by set_current_state().

Tested-by: Anchal Agarwal <anchalag@amazon.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-22 15:07:31 -06:00
Jens Axboe ffa358dcaa blk-wbt: move disable check into get_limit()
Check it in one place, instead of in multiple places.

Tested-by: Anchal Agarwal <anchalag@amazon.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-22 15:07:31 -06:00
Ming Lei df60f6e835 blk-wbt: fix IO hang in wbt_wait()
On wbt invariant is that if one IO is tracked via WBT_TRACKED, rqw->inflight
should be updated for tracking this IO.

But commit c1c80384c8 ("block: remove external dependency on wbt_flags")
forgets to remove the early handling of !rwb_enabled(rwb) inside wbt_wait(),
then the inflight counter may not be increased in wbt_wait(), but decreased
in wbt_done() for this kind of IO, so this counter may become negative, then
wbt_wait() may wait forever.

This patch fixes the report in the following link:

	https://marc.info/?l=linux-block&m=153221542021033&w=2

Fixes: c1c80384c8 ("block: remove external dependency on wbt_flags")
Cc: Josef Bacik <jbacik@fb.com>
Reported-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-14 11:05:52 -06:00
Anchal Agarwal 2887e41b91 blk-wbt: Avoid lock contention and thundering herd issue in wbt_wait
I am currently running a large bare metal instance (i3.metal)
on EC2 with 72 cores, 512GB of RAM and NVME drives, with a
4.18 kernel. I have a workload that simulates a database
workload and I am running into lockup issues when writeback
throttling is enabled,with the hung task detector also
kicking in.

Crash dumps show that most CPUs (up to 50 of them) are
all trying to get the wbt wait queue lock while trying to add
themselves to it in __wbt_wait (see stack traces below).

[    0.948118] CPU: 45 PID: 0 Comm: swapper/45 Not tainted 4.14.51-62.38.amzn1.x86_64 #1
[    0.948119] Hardware name: Amazon EC2 i3.metal/Not Specified, BIOS 1.0 10/16/2017
[    0.948120] task: ffff883f7878c000 task.stack: ffffc9000c69c000
[    0.948124] RIP: 0010:native_queued_spin_lock_slowpath+0xf8/0x1a0
[    0.948125] RSP: 0018:ffff883f7fcc3dc8 EFLAGS: 00000046
[    0.948126] RAX: 0000000000000000 RBX: ffff887f7709ca68 RCX: ffff883f7fce2a00
[    0.948128] RDX: 000000000000001c RSI: 0000000000740001 RDI: ffff887f7709ca68
[    0.948129] RBP: 0000000000000002 R08: 0000000000b80000 R09: 0000000000000000
[    0.948130] R10: ffff883f7fcc3d78 R11: 000000000de27121 R12: 0000000000000002
[    0.948131] R13: 0000000000000003 R14: 0000000000000000 R15: 0000000000000000
[    0.948132] FS:  0000000000000000(0000) GS:ffff883f7fcc0000(0000) knlGS:0000000000000000
[    0.948134] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    0.948135] CR2: 000000c424c77000 CR3: 0000000002010005 CR4: 00000000003606e0
[    0.948136] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[    0.948137] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[    0.948138] Call Trace:
[    0.948139]  <IRQ>
[    0.948142]  do_raw_spin_lock+0xad/0xc0
[    0.948145]  _raw_spin_lock_irqsave+0x44/0x4b
[    0.948149]  ? __wake_up_common_lock+0x53/0x90
[    0.948150]  __wake_up_common_lock+0x53/0x90
[    0.948155]  wbt_done+0x7b/0xa0
[    0.948158]  blk_mq_free_request+0xb7/0x110
[    0.948161]  __blk_mq_complete_request+0xcb/0x140
[    0.948166]  nvme_process_cq+0xce/0x1a0 [nvme]
[    0.948169]  nvme_irq+0x23/0x50 [nvme]
[    0.948173]  __handle_irq_event_percpu+0x46/0x300
[    0.948176]  handle_irq_event_percpu+0x20/0x50
[    0.948179]  handle_irq_event+0x34/0x60
[    0.948181]  handle_edge_irq+0x77/0x190
[    0.948185]  handle_irq+0xaf/0x120
[    0.948188]  do_IRQ+0x53/0x110
[    0.948191]  common_interrupt+0x87/0x87
[    0.948192]  </IRQ>
....
[    0.311136] CPU: 4 PID: 9737 Comm: run_linux_amd64 Not tainted 4.14.51-62.38.amzn1.x86_64 #1
[    0.311137] Hardware name: Amazon EC2 i3.metal/Not Specified, BIOS 1.0 10/16/2017
[    0.311138] task: ffff883f6e6a8000 task.stack: ffffc9000f1ec000
[    0.311141] RIP: 0010:native_queued_spin_lock_slowpath+0xf5/0x1a0
[    0.311142] RSP: 0018:ffffc9000f1efa28 EFLAGS: 00000046
[    0.311144] RAX: 0000000000000000 RBX: ffff887f7709ca68 RCX: ffff883f7f722a00
[    0.311145] RDX: 0000000000000035 RSI: 0000000000d80001 RDI: ffff887f7709ca68
[    0.311146] RBP: 0000000000000202 R08: 0000000000140000 R09: 0000000000000000
[    0.311147] R10: ffffc9000f1ef9d8 R11: 000000001a249fa0 R12: ffff887f7709ca68
[    0.311148] R13: ffffc9000f1efad0 R14: 0000000000000000 R15: ffff887f7709ca00
[    0.311149] FS:  000000c423f30090(0000) GS:ffff883f7f700000(0000) knlGS:0000000000000000
[    0.311150] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[    0.311151] CR2: 00007feefcea4000 CR3: 0000007f7016e001 CR4: 00000000003606e0
[    0.311152] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[    0.311153] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[    0.311154] Call Trace:
[    0.311157]  do_raw_spin_lock+0xad/0xc0
[    0.311160]  _raw_spin_lock_irqsave+0x44/0x4b
[    0.311162]  ? prepare_to_wait_exclusive+0x28/0xb0
[    0.311164]  prepare_to_wait_exclusive+0x28/0xb0
[    0.311167]  wbt_wait+0x127/0x330
[    0.311169]  ? finish_wait+0x80/0x80
[    0.311172]  ? generic_make_request+0xda/0x3b0
[    0.311174]  blk_mq_make_request+0xd6/0x7b0
[    0.311176]  ? blk_queue_enter+0x24/0x260
[    0.311178]  ? generic_make_request+0xda/0x3b0
[    0.311181]  generic_make_request+0x10c/0x3b0
[    0.311183]  ? submit_bio+0x5c/0x110
[    0.311185]  submit_bio+0x5c/0x110
[    0.311197]  ? __ext4_journal_stop+0x36/0xa0 [ext4]
[    0.311210]  ext4_io_submit+0x48/0x60 [ext4]
[    0.311222]  ext4_writepages+0x810/0x11f0 [ext4]
[    0.311229]  ? do_writepages+0x3c/0xd0
[    0.311239]  ? ext4_mark_inode_dirty+0x260/0x260 [ext4]
[    0.311240]  do_writepages+0x3c/0xd0
[    0.311243]  ? _raw_spin_unlock+0x24/0x30
[    0.311245]  ? wbc_attach_and_unlock_inode+0x165/0x280
[    0.311248]  ? __filemap_fdatawrite_range+0xa3/0xe0
[    0.311250]  __filemap_fdatawrite_range+0xa3/0xe0
[    0.311253]  file_write_and_wait_range+0x34/0x90
[    0.311264]  ext4_sync_file+0x151/0x500 [ext4]
[    0.311267]  do_fsync+0x38/0x60
[    0.311270]  SyS_fsync+0xc/0x10
[    0.311272]  do_syscall_64+0x6f/0x170
[    0.311274]  entry_SYSCALL_64_after_hwframe+0x42/0xb7

In the original patch, wbt_done is waking up all the exclusive
processes in the wait queue, which can cause a thundering herd
if there is a large number of writer threads in the queue. The
original intention of the code seems to be to wake up one thread
only however, it uses wake_up_all() in __wbt_done(), and then
uses the following check in __wbt_wait to have only one thread
actually get out of the wait loop:

if (waitqueue_active(&rqw->wait) &&
            rqw->wait.head.next != &wait->entry)
                return false;

The problem with this is that the wait entry in wbt_wait is
define with DEFINE_WAIT, which uses the autoremove wakeup function.
That means that the above check is invalid - the wait entry will
have been removed from the queue already by the time we hit the
check in the loop.

Secondly, auto-removing the wait entries also means that the wait
queue essentially gets reordered "randomly" (e.g. threads re-add
themselves in the order they got to run after being woken up).
Additionally, new requests entering wbt_wait might overtake requests
that were queued earlier, because the wait queue will be
(temporarily) empty after the wake_up_all, so the waitqueue_active
check will not stop them. This can cause certain threads to starve
under high load.

The fix is to leave the woken up requests in the queue and remove
them in finish_wait() once the current thread breaks out of the
wait loop in __wbt_wait. This will ensure new requests always
end up at the back of the queue, and they won't overtake requests
that are already in the wait queue. With that change, the loop
in wbt_wait is also in line with many other wait loops in the kernel.
Waking up just one thread drastically reduces lock contention, as
does moving the wait queue add/remove out of the loop.

A significant drop in lockdep's lock contention numbers is seen when
running the test application on the patched kernel.

Signed-off-by: Anchal Agarwal <anchalag@amazon.com>
Signed-off-by: Frank van der Linden <fllinden@amazon.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-07 14:40:49 -06:00
Josef Bacik c1c80384c8 block: remove external dependency on wbt_flags
We don't really need to save this stuff in the core block code, we can
just pass the bio back into the helpers later on to derive the same
flags and update the rq->wbt_flags appropriately.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-09 09:07:54 -06:00
Josef Bacik a79050434b blk-rq-qos: refactor out common elements of blk-wbt
blkcg-qos is going to do essentially what wbt does, only on a cgroup
basis.  Break out the common code that will be shared between blkcg-qos
and wbt into blk-rq-qos.* so they can both utilize the same
infrastructure.

Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-07-09 09:07:54 -06:00
Omar Sandoval 544ccc8dc9 block: get rid of struct blk_issue_stat
struct blk_issue_stat squashes three things into one u64:

- The time the driver started working on a request
- The original size of the request (for the io.low controller)
- Flags for writeback throttling

It turns out that on x86_64, we have a 4 byte hole in struct request
which we can fill with the non-timestamp fields from blk_issue_stat,
simplifying things quite a bit.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-09 08:33:05 -06:00
Omar Sandoval a8a4594170 block: pass struct request instead of struct blk_issue_stat to wbt
issue_stat is going to go away, so first make writeback throttling take
the containing request, update the internal wbt helpers accordingly, and
change rwb->sync_cookie to be the request pointer instead of the
issue_stat pointer. No functional change.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-09 08:33:02 -06:00
Omar Sandoval 934031a129 block: move some wbt helpers to blk-wbt.c
A few helpers are only used from blk-wbt.c, so move them there, and put
wbt_track() behind the CONFIG_BLK_WBT typedef. This is in preparation
for changing how the wbt flags are tracked.

Signed-off-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-09 08:33:00 -06:00
Jens Axboe 782f569774 blk-wbt: throttle discards like background writes
Throttle discards like we would any background write. Discards should
be background activity, so if they are impacting foreground IO, then
we will throttle them down.

Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-05-08 15:11:02 -06:00