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2022-10-23blk-wbt: don't enable throttling if default elevator is bfqGravatar Yu Kuai 1-3/+8
Commit b5dc5d4d1f4f ("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>
2022-10-23blk-wbt: don't show valid wbt_lat_usec in sysfs while wbt is disabledGravatar Yu Kuai 1-0/+8
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>
2022-10-23blk-wbt: make enable_state more accurateGravatar Yu Kuai 1-1/+6
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>
2022-10-23blk-wbt: remove unnecessary check in wbt_enable_default()Gravatar Yu Kuai 1-1/+1
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>
2022-10-09blk-wbt: fix that 'rwb->wc' is always set to 1 in wbt_init()Gravatar Yu Kuai 1-2/+1
commit 8c5035dfbb94 ("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: 8c5035dfbb94 ("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>
2022-09-21blk-wbt: call rq_qos_add() after wb_normal is initializedGravatar Yu Kuai 1-5/+4
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 8235b5c1e8c1 ("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: e34cbd307477 ("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>
2022-07-20block: don't allow the same type rq_qos add more than onceGravatar Jinke Han 1-1/+11
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>
2022-07-14block: Use the new blk_opf_t typeGravatar Bart Van Assche 1-8/+8
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>
2022-07-14block: Use enum req_op where appropriateGravatar Bart Van Assche 1-1/+1
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>
2021-10-19blk-wbt: prevent NULL pointer dereference in wb_timer_fnGravatar Andrea Righi 1-0/+3
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: 34dbad5d26e2 ("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>
2021-08-23block: add an explicit ->disk backpointer to the request_queueGravatar Christoph Hellwig 1-5/+5
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: edb0872f44ec ("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>
2021-08-09block: move the bdi from the request_queue to the gendiskGravatar Christoph Hellwig 1-5/+5
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>
2021-06-21blk-wbt: make sure throttle is enabled properlyGravatar Zhang Yi 1-1/+5
After commit a79050434b45 ("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: a79050434b45 ("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>
2021-06-21blk-wbt: introduce a new disable state to prevent false positive by ↵Gravatar Zhang Yi 1-2/+3
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: a79050434b45 ("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>
2021-06-18blk-wbt: remove outdated commentGravatar lijiazi 1-1/+0
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>
2021-01-26blk: wbt: remove unused parameter from wbt_should_throttleGravatar Lei Chen 1-2/+2
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>
2020-11-30block: wbt: Remove unnecessary invoking of wbt_update_limits in wbt_initGravatar Lei Chen 1-1/+0
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>
2020-08-23treewide: Use fallthrough pseudo-keywordGravatar Gustavo A. R. Silva 1-1/+1
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>
2020-05-29blk-wbt: rename __wbt_update_limits to wbt_update_limitsGravatar Guoqing Jiang 1-4/+4
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>
2020-05-29blk-wbt: remove wbt_update_limitsGravatar Guoqing Jiang 1-8/+0
No one call this function after commit 2af2783f2ea4f ("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>
2020-04-17blk-wbt: Use tracepoint_string() for wbt_step tracepoint string literalsGravatar Tommi Rantala 1-2/+2
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>
2019-10-06blk-wbt: fix performance regression in wbt scale_up/scale_downGravatar Harshad Shirwadkar 1-2/+4
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: a79050434b45 ("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>
2019-08-28block/rq_qos: implement rq_qos_ops->queue_depth_changed()Gravatar Tejun Heo 1-10/+8
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>
2019-08-27block: add helper for checking if queue is registeredGravatar Ming Lei 1-1/+1
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>
2019-04-30block: add SPDX tags to block layer files missing licensing informationGravatar Christoph Hellwig 1-0/+1
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>
2019-01-24blk-wbt: Declare local functions staticGravatar Bart Van Assche 1-2/+2
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>
2018-12-16blk-wbt: export internal state via debugfsGravatar Ming Lei 1-0/+91
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>
2018-12-12block: deactivate blk_stat timer in wbt_disable_default()Gravatar Ming Lei 1-1/+3
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>
2018-12-07block: convert wbt_wait() to use rq_qos_wait()Gravatar Josef Bacik 1-54/+11
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>
2018-11-16block: add queue_is_mq() helperGravatar Jens Axboe 1-1/+1
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>
2018-11-15block: add wbt_disable_default export for BFQGravatar Jens Axboe 1-0/+1
This isn't unused, if BFQ is modular we get into trouble. Fixes: b6676f653f13 ("block: remove a few unused exports") Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-15block: remove a few unused exportsGravatar Christoph Hellwig 1-2/+0
Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-11-15block: remove the unused lock argument to rq_qos_throttleGravatar Christoph Hellwig 1-12/+4
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>
2018-11-07blk-wbt: kill check for legacy queue typeGravatar Jens Axboe 1-2/+1
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>
2018-10-11blk-wbt: wake up all when we scale up, not downGravatar Josef Bacik 1-1/+1
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: a79050434b45 ("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>
2018-08-27blk-wbt: remove dead codeGravatar Jens Axboe 1-5/+0
We already note and mark discard and swap IO from bio_to_wbt_flags(). Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-27blk-wbt: improve waking of tasksGravatar Jens Axboe 1-7/+56
We have two potential issues: 1) After commit 2887e41b910b, 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>
2018-08-27blk-wbt: abstract out end IO completion handlerGravatar Jens Axboe 1-7/+14
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>
2018-08-23blk-wbt: don't maintain inflight counts if disabledGravatar Jens Axboe 1-0/+3
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: c1c80384c8f ("block: remove external dependency on wbt_flags") Reviewed-by: Josef Bacik <josef@toxicpanda.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2018-08-22blk-wbt: fix has-sleeper queueing checkGravatar Jens Axboe 1-3/+5
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>
2018-08-22blk-wbt: use wq_has_sleeper() for wq active checkGravatar Jens Axboe 1-4/+4
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>
2018-08-22blk-wbt: move disable check into get_limit()Gravatar Jens Axboe 1-15/+7
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>
2018-08-14blk-wbt: fix IO hang in wbt_wait()Gravatar Ming Lei 1-5/+1
On wbt invariant is that if one IO is tracked via WBT_TRACKED, rqw->inflight should be updated for tracking this IO. But commit c1c80384c8f ("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: c1c80384c8f ("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>
2018-08-07blk-wbt: Avoid lock contention and thundering herd issue in wbt_waitGravatar Anchal Agarwal 1-31/+24
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>
2018-07-09block: remove external dependency on wbt_flagsGravatar Josef Bacik 1-13/+39
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>
2018-07-09blk-rq-qos: refactor out common elements of blk-wbtGravatar Josef Bacik 1-182/+144
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>
2018-05-09block: get rid of struct blk_issue_statGravatar Omar Sandoval 1-7/+5
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>
2018-05-09block: pass struct request instead of struct blk_issue_stat to wbtGravatar Omar Sandoval 1-27/+26
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>
2018-05-09block: move some wbt helpers to blk-wbt.cGravatar Omar Sandoval 1-0/+20
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>
2018-05-08blk-wbt: throttle discards like background writesGravatar Jens Axboe 1-17/+26
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>
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