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2021-05-12block, bfq: avoid circular stable mergesPaolo Valente1-2/+29
BFQ may merge a new bfq_queue, stably, with the last bfq_queue created. In particular, BFQ first waits a little bit for some I/O to flow inside the new queue, say Q2, if this is needed to understand whether it is better or worse to merge Q2 with the last queue created, say Q1. This delayed stable merge is performed by assigning bic->stable_merge_bfqq = Q1, for the bic associated with Q1. Yet, while waiting for some I/O to flow in Q2, a non-stable queue merge of Q2 with Q1 may happen, causing the bic previously associated with Q2 to be associated with exactly Q1 (bic->bfqq = Q1). After that, Q2 and Q1 may happen to be split, and, in the split, Q1 may happen to be recycled as a non-shared bfq_queue. In that case, Q1 may then happen to undergo a stable merge with the bfq_queue pointed by bic->stable_merge_bfqq. Yet bic->stable_merge_bfqq still points to Q1. So Q1 would be merged with itself. This commit fixes this error by intercepting this situation, and canceling the schedule of the stable merge. Fixes: 430a67f9d616 ("block, bfq: merge bursts of newly-created queues") Signed-off-by: Pietro Pedroni <pedroni.pietro.96@gmail.com> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Link: https://lore.kernel.org/r/20210512094352.85545-2-paolo.valente@linaro.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-05-11kyber: fix out of bounds access when preemptedOmar Sandoval1-2/+1
__blk_mq_sched_bio_merge() gets the ctx and hctx for the current CPU and passes the hctx to ->bio_merge(). kyber_bio_merge() then gets the ctx for the current CPU again and uses that to get the corresponding Kyber context in the passed hctx. However, the thread may be preempted between the two calls to blk_mq_get_ctx(), and the ctx returned the second time may no longer correspond to the passed hctx. This "works" accidentally most of the time, but it can cause us to read garbage if the second ctx came from an hctx with more ctx's than the first one (i.e., if ctx->index_hw[hctx->type] > hctx->nr_ctx). This manifested as this UBSAN array index out of bounds error reported by Jakub: UBSAN: array-index-out-of-bounds in ../kernel/locking/qspinlock.c:130:9 index 13106 is out of range for type 'long unsigned int [128]' Call Trace: dump_stack+0xa4/0xe5 ubsan_epilogue+0x5/0x40 __ubsan_handle_out_of_bounds.cold.13+0x2a/0x34 queued_spin_lock_slowpath+0x476/0x480 do_raw_spin_lock+0x1c2/0x1d0 kyber_bio_merge+0x112/0x180 blk_mq_submit_bio+0x1f5/0x1100 submit_bio_noacct+0x7b0/0x870 submit_bio+0xc2/0x3a0 btrfs_map_bio+0x4f0/0x9d0 btrfs_submit_data_bio+0x24e/0x310 submit_one_bio+0x7f/0xb0 submit_extent_page+0xc4/0x440 __extent_writepage_io+0x2b8/0x5e0 __extent_writepage+0x28d/0x6e0 extent_write_cache_pages+0x4d7/0x7a0 extent_writepages+0xa2/0x110 do_writepages+0x8f/0x180 __writeback_single_inode+0x99/0x7f0 writeback_sb_inodes+0x34e/0x790 __writeback_inodes_wb+0x9e/0x120 wb_writeback+0x4d2/0x660 wb_workfn+0x64d/0xa10 process_one_work+0x53a/0xa80 worker_thread+0x69/0x5b0 kthread+0x20b/0x240 ret_from_fork+0x1f/0x30 Only Kyber uses the hctx, so fix it by passing the request_queue to ->bio_merge() instead. BFQ and mq-deadline just use that, and Kyber can map the queues itself to avoid the mismatch. Fixes: a6088845c2bf ("block: kyber: make kyber more friendly with merging") Reported-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Omar Sandoval <osandov@fb.com> Link: https://lore.kernel.org/r/c7598605401a48d5cfeadebb678abd10af22b83f.1620691329.git.osandov@fb.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-04-16bfq/mq-deadline: remove redundant check for passthrough requestLin Feng1-2/+1
Since commit 01e99aeca39796003 'blk-mq: insert passthrough request into hctx->dispatch directly', passthrough request should not appear in IO-scheduler any more, so blk_rq_is_passthrough checking in addon IO schedulers is redundant. (Notes: this patch passes generic IO load test with hdds under SAS controller and hdds under AHCI controller but obviously not covers all. Not sure if passthrough request can still escape into IO scheduler from blk_mq_sched_insert_requests, which is used by blk_mq_flush_plug_list and has lots of indirect callers.) Signed-off-by: Lin Feng <linf@wangsu.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-03-25block, bfq: merge bursts of newly-created queuesPaolo Valente1-10/+249
Many throughput-sensitive workloads are made of several parallel I/O flows, with all flows generated by the same application, or more generically by the same task (e.g., system boot). The most counterproductive action with these workloads is plugging I/O dispatch when one of the bfq_queues associated with these flows remains temporarily empty. To avoid this plugging, BFQ has been using a burst-handling mechanism for years now. This mechanism has proven effective for throughput, and not detrimental for service guarantees. This commit pushes this mechanism a little bit further, basing on the following two facts. First, all the I/O flows of a the same application or task contribute to the execution/completion of that common application or task. So the performance figures that matter are total throughput of the flows and task-wide I/O latency. In particular, these flows do not need to be protected from each other, in terms of individual bandwidth or latency. Second, the above fact holds regardless of the number of flows. Putting these two facts together, this commits merges stably the bfq_queues associated with these I/O flows, i.e., with the processes that generate these IO/ flows, regardless of how many the involved processes are. To decide whether a set of bfq_queues is actually associated with the I/O flows of a common application or task, and to merge these queues stably, this commit operates as follows: given a bfq_queue, say Q2, currently being created, and the last bfq_queue, say Q1, created before Q2, Q2 is merged stably with Q1 if - very little time has elapsed since when Q1 was created - Q2 has the same ioprio as Q1 - Q2 belongs to the same group as Q1 Merging bfq_queues also reduces scheduling overhead. A fio test with ten random readers on /dev/nullb shows a throughput boost of 40%, with a quadcore. Since BFQ's execution time amounts to ~50% of the total per-request processing time, the above throughput boost implies that BFQ's overhead is reduced by more than 50%. Tested-by: Jan Kara <jack@suse.cz> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Link: https://lore.kernel.org/r/20210304174627.161-7-paolo.valente@linaro.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-03-25block, bfq: keep shared queues out of the waker mechanismPaolo Valente1-1/+11
Shared queues are likely to receive I/O at a high rate. This may deceptively let them be considered as wakers of other queues. But a false waker will unjustly steal bandwidth to its supposedly woken queue. So considering also shared queues in the waking mechanism may cause more control troubles than throughput benefits. This commit keeps shared queues out of the waker-detection mechanism. Tested-by: Jan Kara <jack@suse.cz> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Link: https://lore.kernel.org/r/20210304174627.161-6-paolo.valente@linaro.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-03-25block, bfq: fix weight-raising resume with !low_latencyPaolo Valente1-2/+8
When the io_latency heuristic is off, bfq_queues must not start to be weight-raised. Unfortunately, by mistake, this may happen when the state of a previously weight-raised bfq_queue is resumed after a queue split. This commit fixes this error. Tested-by: Jan Kara <jack@suse.cz> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Link: https://lore.kernel.org/r/20210304174627.161-5-paolo.valente@linaro.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-03-25block, bfq: make shared queues inherit wakersPaolo Valente1-3/+39
Consider a bfq_queue bfqq that is about to be merged with another bfq_queue new_bfqq. The processes associated with bfqq are cooperators of the processes associated with new_bfqq. So, if bfqq has a waker, then it is reasonable (and beneficial for throughput) to assume that all these processes will be happy to let bfqq's waker freely inject I/O when they have no I/O. So this commit makes new_bfqq inherit bfqq's waker. Tested-by: Jan Kara <jack@suse.cz> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Link: https://lore.kernel.org/r/20210304174627.161-4-paolo.valente@linaro.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-03-25block, bfq: put reqs of waker and woken in dispatch listPaolo Valente1-1/+43
Consider a new I/O request that arrives for a bfq_queue bfqq. If, when this happens, the only active bfq_queues are bfqq and either its waker bfq_queue or one of its woken bfq_queues, then there is no point in queueing this new I/O request in bfqq for service. In fact, the in-service queue and bfqq agree on serving this new I/O request as soon as possible. So this commit puts this new I/O request directly into the dispatch list. Tested-by: Jan Kara <jack@suse.cz> Acked-by: Jan Kara <jack@suse.cz> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Link: https://lore.kernel.org/r/20210304174627.161-3-paolo.valente@linaro.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-03-25block, bfq: always inject I/O of queues blocked by wakersPaolo Valente1-5/+27
Suppose that I/O dispatch is plugged, to wait for new I/O for the in-service bfq-queue, say bfqq. Suppose then that there is a further bfq_queue woken by bfqq, and that this woken queue has pending I/O. A woken queue does not steal bandwidth from bfqq, because it remains soon without I/O if bfqq is not served. So there is virtually no risk of loss of bandwidth for bfqq if this woken queue has I/O dispatched while bfqq is waiting for new I/O. In contrast, this extra I/O injection boosts throughput. This commit performs this extra injection. Tested-by: Jan Kara <jack@suse.cz> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Link: https://lore.kernel.org/r/20210304174627.161-2-paolo.valente@linaro.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-03-02block/bfq: update comments and default value in docs for fifo_expireJoseph Qi1-1/+1
Correct the comments since bfq_fifo_expire[0] is for async request, while bfq_fifo_expire[1] is for sync request. Also update docs, according the source code, the default fifo_expire_async is 250ms, and fifo_expire_sync is 125ms. Signed-off-by: Joseph Qi <joseph.qi@linux.alibaba.com> Acked-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-02-22block: get rid of the trace rq insert wrapperChaitanya Kulkarni1-1/+3
Get rid of the wrapper for trace_block_rq_insert() and call the function directly. Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Damien Le Moal <damien.lemoal@wdc.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-02-21Merge tag 'for-5.12/block-2021-02-17' of git://git.kernel.dk/linux-blockLinus Torvalds1-169/+276
Pull core block updates from Jens Axboe: "Another nice round of removing more code than what is added, mostly due to Christoph's relentless pursuit of tech debt removal/cleanups. This pull request contains: - Two series of BFQ improvements (Paolo, Jan, Jia) - Block iov_iter improvements (Pavel) - bsg error path fix (Pan) - blk-mq scheduler improvements (Jan) - -EBUSY discard fix (Jan) - bvec allocation improvements (Ming, Christoph) - bio allocation and init improvements (Christoph) - Store bdev pointer in bio instead of gendisk + partno (Christoph) - Block trace point cleanups (Christoph) - hard read-only vs read-only split (Christoph) - Block based swap cleanups (Christoph) - Zoned write granularity support (Damien) - Various fixes/tweaks (Chunguang, Guoqing, Lei, Lukas, Huhai)" * tag 'for-5.12/block-2021-02-17' of git://git.kernel.dk/linux-block: (104 commits) mm: simplify swapdev_block sd_zbc: clear zone resources for non-zoned case block: introduce blk_queue_clear_zone_settings() zonefs: use zone write granularity as block size block: introduce zone_write_granularity limit block: use blk_queue_set_zoned in add_partition() nullb: use blk_queue_set_zoned() to setup zoned devices nvme: cleanup zone information initialization block: document zone_append_max_bytes attribute block: use bi_max_vecs to find the bvec pool md/raid10: remove dead code in reshape_request block: mark the bio as cloned in bio_iov_bvec_set block: set BIO_NO_PAGE_REF in bio_iov_bvec_set block: remove a layer of indentation in bio_iov_iter_get_pages block: turn the nr_iovecs argument to bio_alloc* into an unsigned short block: remove the 1 and 4 vec bvec_slabs entries block: streamline bvec_alloc block: factor out a bvec_alloc_gfp helper block: move struct biovec_slab to bio.c block: reuse BIO_INLINE_VECS for integrity bvecs ...
2021-02-02bfq-iosched: Revert "bfq: Fix computation of shallow depth"Lin Feng1-4/+4
This reverts commit 6d4d273588378c65915acaf7b2ee74e9dd9c130a. bfq.limit_depth passes word_depths[] as shallow_depth down to sbitmap core sbitmap_get_shallow, which uses just the number to limit the scan depth of each bitmap word, formula: scan_percentage_for_each_word = shallow_depth / (1 << sbimap->shift) * 100% That means the comments's percentiles 50%, 75%, 18%, 37% of bfq are correct. But after commit patch 'bfq: Fix computation of shallow depth', we use sbitmap.depth instead, as a example in following case: sbitmap.depth = 256, map_nr = 4, shift = 6; sbitmap_word.depth = 64. The resulsts of computed bfqd->word_depths[] are {128, 192, 48, 96}, and three of the numbers exceed core dirver's 'sbitmap_word.depth=64' limit nothing. Signed-off-by: Lin Feng <linf@wangsu.com> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-27bfq: Use only idle IO periods for think time calculationsJan Kara1-1/+9
Currently whenever bfq queue has a request queued we add now - last_completion_time to the think time statistics. This is however misleading in case the process is able to submit several requests in parallel because e.g. if the queue has request completed at time T0 and then queues new requests at times T1, T2, then we will add T1-T0 and T2-T0 to think time statistics which just doesn't make any sence (the queue's think time is penalized by the queue being able to submit more IO). So add to think time statistics only time intervals when the queue had no IO pending. Signed-off-by: Jan Kara <jack@suse.cz> Acked-by: Paolo Valente <paolo.valente@linaro.org> [axboe: fix whitespace on empty line] Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-27bfq: Use 'ttime' local variableJan Kara1-1/+1
Use local variable 'ttime' instead of dereferencing bfqq. Signed-off-by: Jan Kara <jack@suse.cz> Acked-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-27bfq: Avoid false bfq queue mergingJan Kara1-0/+1
bfq_setup_cooperator() uses bfqd->in_serv_last_pos so detect whether it makes sense to merge current bfq queue with the in-service queue. However if the in-service queue is freshly scheduled and didn't dispatch any requests yet, bfqd->in_serv_last_pos is stale and contains value from the previously scheduled bfq queue which can thus result in a bogus decision that the two queues should be merged. This bug can be observed for example with the following fio jobfile: [global] direct=0 ioengine=sync invalidate=1 size=1g rw=read [reader] numjobs=4 directory=/mnt where the 4 processes will end up in the one shared bfq queue although they do IO to physically very distant files (for some reason I was able to observe this only with slice_idle=1ms setting). Fix the problem by invalidating bfqd->in_serv_last_pos when switching in-service queue. Fixes: 058fdecc6de7 ("block, bfq: fix in-service-queue check for queue merging") CC: stable@vger.kernel.org Signed-off-by: Jan Kara <jack@suse.cz> Acked-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-25bfq: bfq_check_waker() should be staticJens Axboe1-1/+2
It's only used in the same file, mark is appropriately static. Fixes: 71217df39dc6 ("block, bfq: make waker-queue detection more robust") Reported-by: kernel test robot <lkp@intel.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-25block, bfq: make waker-queue detection more robustPaolo Valente1-108/+103
In the presence of many parallel I/O flows, the detection of waker bfq_queues suffers from false positives. This commits addresses this issue by making the filtering of actual wakers more selective. In more detail, a candidate waker must be found to meet waker requirements three times before being promoted to actual waker. Tested-by: Jan Kara <jack@suse.cz> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-25block, bfq: save also injection state on queue mergingPaolo Valente1-0/+8
To prevent injection information from being lost on bfq_queue merging, also the amount of service that a bfq_queue receives must be saved and restored when the bfq_queue is merged and split, respectively. Tested-by: Jan Kara <jack@suse.cz> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-25block, bfq: save also weight-raised service on queue mergingPaolo Valente1-0/+2
To prevent weight-raising information from being lost on bfq_queue merging, also the amount of service that a bfq_queue receives must be saved and restored when the bfq_queue is merged and split, respectively. Tested-by: Jan Kara <jack@suse.cz> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-25block, bfq: fix switch back from soft-rt weitgh-raisingPaolo Valente1-2/+20
A bfq_queue may happen to be deemed as soft real-time while it is still enjoying interactive weight-raising. If this happens because of a false positive, then the bfq_queue is likely to loose its soft real-time status soon. Upon losing such a status, the bfq_queue must get back its interactive weight-raising, if its interactive period is not over yet. But this case is not handled. This commit corrects this error. Tested-by: Jan Kara <jack@suse.cz> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-25block, bfq: re-evaluate convenience of I/O plugging on rq arrivalsPaolo Valente1-5/+19
Upon an I/O-dispatch attempt, BFQ may detect that it was better to plug I/O dispatch, and to wait for a new request to arrive for the currently in-service queue. But the arrival of a new request for an empty bfq_queue, and thus the switch from idle to busy of the bfq_queue, may cause the scenario to change, and make plugging no longer needed for service guarantees, or more convenient for throughput. In this case, keeping I/O-dispatch plugged would certainly lower throughput. To address this issue, this commit makes such a check, and stops plugging I/O if it is better to stop plugging I/O. Tested-by: Jan Kara <jack@suse.cz> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-25block, bfq: replace mechanism for evaluating I/O intensityPaolo Valente1-19/+44
Some BFQ mechanisms make their decisions on a bfq_queue basing also on whether the bfq_queue is I/O bound. In this respect, the current logic for evaluating whether a bfq_queue is I/O bound is rather rough. This commits replaces this logic with a more effective one. The new logic measures the percentage of time during which a bfq_queue is active, and marks the bfq_queue as I/O bound if the latter if this percentage is above a fixed threshold. Tested-by: Jan Kara <jack@suse.cz> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-24Revert "blk-mq, elevator: Count requests per hctx to improve performance"Jan Kara1-5/+0
This reverts commit b445547ec1bbd3e7bf4b1c142550942f70527d95. Since both mq-deadline and BFQ completely ignore hctx they are passed to their dispatch function and dispatch whatever request they deem fit checking whether any request for a particular hctx is queued is just pointless since we'll very likely get a request from a different hctx anyway. In the following commit we'll deal with lock contention in these IO schedulers in presence of multiple HW queues in a different way. Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-24block, bfq: do not expire a queue when it is the only busy onePaolo Valente1-2/+20
This commits preserves I/O-dispatch plugging for a special symmetric case that may suddenly turn into asymmetric: the case where only one bfq_queue, say bfqq, is busy. In this case, not expiring bfqq does not cause any harm to any other queues in terms of service guarantees. In contrast, it avoids the following unlucky sequence of events: (1) bfqq is expired, (2) a new queue with a lower weight than bfqq becomes busy (or more queues), (3) the new queue is served until a new request arrives for bfqq, (4) when bfqq is finally served, there are so many requests of the new queue in the drive that the pending requests for bfqq take a lot of time to be served. In particular, event (2) may case even already dispatched requests of bfqq to be delayed, inside the drive. So, to avoid this series of events, the scenario is preventively declared as asymmetric also if bfqq is the only busy queues. By doing so, I/O-dispatch plugging is performed for bfqq. Tested-by: Jan Kara <jack@suse.cz> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-24block, bfq: avoid spurious switches to soft_rt of interactive queuesPaolo Valente1-20/+37
BFQ tags some bfq_queues as interactive or soft_rt if it deems that these bfq_queues contain the I/O of, respectively, interactive or soft real-time applications. BFQ privileges both these special types of bfq_queues over normal bfq_queues. To privilege a bfq_queue, BFQ mainly raises the weight of the bfq_queue. In particular, soft_rt bfq_queues get a higher weight than interactive bfq_queues. A bfq_queue may turn from interactive to soft_rt. And this leads to a tricky issue. Soft real-time applications usually start with an I/O-bound, interactive phase, in which they load themselves into main memory. BFQ correctly detects this phase, and keeps the bfq_queues associated with the application in interactive mode for a while. Problems arise when the I/O pattern of the application finally switches to soft real-time. One of the conditions for a bfq_queue to be deemed as soft_rt is that the bfq_queue does not consume too much bandwidth. But the bfq_queues associated with a soft real-time application consume as much bandwidth as they can in the loading phase of the application. So, after the application becomes truly soft real-time, a lot of time should pass before the average bandwidth consumed by its bfq_queues finally drops to a value acceptable for soft_rt bfq_queues. As a consequence, there might be a time gap during which the application is not privileged at all, because its bfq_queues are not interactive any longer, but cannot be deemed as soft_rt yet. To avoid this problem, BFQ pretends that an interactive bfq_queue consumes zero bandwidth, and allows an interactive bfq_queue to switch to soft_rt. Yet, this fake zero-bandwidth consumption easily causes the bfq_queue to often switch to soft_rt deceptively, during its loading phase. As in soft_rt mode, the bfq_queue gets its bandwidth correctly computed, and therefore soon switches back to interactive. Then it switches again to soft_rt, and so on. These spurious fluctuations usually cause losses of throughput, because they deceive BFQ's mechanisms for boosting throughput (injection, I/O-plugging avoidance, ...). This commit addresses this issue as follows: 1) It does compute actual bandwidth consumption also for interactive bfq_queues. This avoids the above false positives. 2) When a bfq_queue switches from interactive to normal mode, the consumed bandwidth is reset (forgotten). This allows the bfq_queue to enjoy soft_rt very quickly. In particular, two alternatives are possible in this switch: - the bfq_queue still has backlog, and therefore there is a budget already scheduled to serve the bfq_queue; in this case, the scheduling of the current budget of the bfq_queue is not hindered, because only the scheduling of the next budget will be affected by the weight drop. After that, if the bfq_queue is actually in a soft_rt phase, and becomes empty during the service of its current budget, which is the natural behavior of a soft_rt bfq_queue, then the bfq_queue will be considered as soft_rt when its next I/O arrives. If, in contrast, the bfq_queue remains constantly non-empty, then its next budget will be scheduled with a low weight, which is the natural treatment for an I/O-bound (non soft_rt) bfq_queue. - the bfq_queue is empty; in this case, the bfq_queue may be considered unjustly soft_rt when its new I/O arrives. Yet the problem is now much smaller than before, because it is unlikely that more than one spurious fluctuation occurs. Tested-by: Jan Kara <jack@suse.cz> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-24block, bfq: do not raise non-default weightsPaolo Valente1-3/+7
BFQ heuristics try to detect interactive I/O, and raise the weight of the queues containing such an I/O. Yet, if also the user changes the weight of a queue (i.e., the user changes the ioprio of the process associated with that queue), then it is most likely better to prevent BFQ heuristics from silently changing the same weight. Tested-by: Jan Kara <jack@suse.cz> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-24block, bfq: increase time window for waker detectionPaolo Valente1-1/+1
Tests on slower machines showed current window to be way too small. This commit increases it. Tested-by: Jan Kara <jack@suse.cz> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-24block, bfq: set next_rq to waker_bfqq->next_rq in waker injectionJia Cheng Hu1-1/+1
Since commit c5089591c3ba ("block, bfq: detect wakers and unconditionally inject their I/O"), when the in-service bfq_queue, say Q, is temporarily empty, BFQ checks whether there are I/O requests to inject (also) from the waker bfq_queue for Q. To this goal, the value pointed by bfqq->waker_bfqq->next_rq must be controlled. However, the current implementation mistakenly looks at bfqq->next_rq, which instead points to the next request of the currently served queue. This mistake evidently causes losses of throughput in scenarios with waker bfq_queues. This commit corrects this mistake. Fixes: c5089591c3ba ("block, bfq: detect wakers and unconditionally inject their I/O") Signed-off-by: Jia Cheng Hu <jia.jiachenghu@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-24block, bfq: use half slice_idle as a threshold to check short ttimePaolo Valente1-3/+4
The value of the I/O plugging (idling) timeout is used also as the think-time threshold to decide whether a process has a short think time. In this respect, a good value of this timeout for rotational drives is un the order of several ms. Yet, this is often too long a time interval to be effective as a think-time threshold. This commit mitigates this problem (by a lot, according to tests), by halving the threshold. Tested-by: Jan Kara <jack@suse.cz> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2021-01-05bfq: Fix computation of shallow depthJan Kara1-4/+4
BFQ computes number of tags it allows to be allocated for each request type based on tag bitmap. However it uses 1 << bitmap.shift as number of available tags which is wrong. 'shift' is just an internal bitmap value containing logarithm of how many bits bitmap uses in each bitmap word. Thus number of tags allowed for some request types can be far to low. Use proper bitmap.depth which has the number of tags instead. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-10-13Merge tag 'block-5.10-2020-10-12' of git://git.kernel.dk/linux-blockLinus Torvalds1-2/+7
Pull block updates from Jens Axboe: - Series of merge handling cleanups (Baolin, Christoph) - Series of blk-throttle fixes and cleanups (Baolin) - Series cleaning up BDI, seperating the block device from the backing_dev_info (Christoph) - Removal of bdget() as a generic API (Christoph) - Removal of blkdev_get() as a generic API (Christoph) - Cleanup of is-partition checks (Christoph) - Series reworking disk revalidation (Christoph) - Series cleaning up bio flags (Christoph) - bio crypt fixes (Eric) - IO stats inflight tweak (Gabriel) - blk-mq tags fixes (Hannes) - Buffer invalidation fixes (Jan) - Allow soft limits for zone append (Johannes) - Shared tag set improvements (John, Kashyap) - Allow IOPRIO_CLASS_RT for CAP_SYS_NICE (Khazhismel) - DM no-wait support (Mike, Konstantin) - Request allocation improvements (Ming) - Allow md/dm/bcache to use IO stat helpers (Song) - Series improving blk-iocost (Tejun) - Various cleanups (Geert, Damien, Danny, Julia, Tetsuo, Tian, Wang, Xianting, Yang, Yufen, yangerkun) * tag 'block-5.10-2020-10-12' of git://git.kernel.dk/linux-block: (191 commits) block: fix uapi blkzoned.h comments blk-mq: move cancel of hctx->run_work to the front of blk_exit_queue blk-mq: get rid of the dead flush handle code path block: get rid of unnecessary local variable block: fix comment and add lockdep assert blk-mq: use helper function to test hw stopped block: use helper function to test queue register block: remove redundant mq check block: invoke blk_mq_exit_sched no matter whether have .exit_sched percpu_ref: don't refer to ref->data if it isn't allocated block: ratelimit handle_bad_sector() message blk-throttle: Re-use the throtl_set_slice_end() blk-throttle: Open code __throtl_de/enqueue_tg() blk-throttle: Move service tree validation out of the throtl_rb_first() blk-throttle: Move the list operation after list validation blk-throttle: Fix IO hang for a corner case blk-throttle: Avoid tracking latency if low limit is invalid blk-throttle: Avoid getting the current time if tg->last_finish_time is 0 blk-throttle: Remove a meaningless parameter for throtl_downgrade_state() block: Remove redundant 'return' statement ...
2020-09-11Merge tag 'block-5.9-2020-09-11' of git://git.kernel.dk/linux-blockLinus Torvalds1-12/+0
Pull block fixes from Jens Axboe: - Fix a regression in bdev partition locking (Christoph) - NVMe pull request from Christoph: - cancel async events before freeing them (David Milburn) - revert a broken race fix (James Smart) - fix command processing during resets (Sagi Grimberg) - Fix a kyber crash with requeued flushes (Omar) - Fix __bio_try_merge_page() same_page error for no merging (Ritesh) * tag 'block-5.9-2020-09-11' of git://git.kernel.dk/linux-block: block: Set same_page to false in __bio_try_merge_page if ret is false nvme-fabrics: allow to queue requests for live queues block: only call sched requeue_request() for scheduled requests nvme-tcp: cancel async events before freeing event struct nvme-rdma: cancel async events before freeing event struct nvme-fc: cancel async events before freeing event struct nvme: Revert: Fix controller creation races with teardown flow block: restore a specific error code in bdev_del_partition
2020-09-08block: only call sched requeue_request() for scheduled requestsOmar Sandoval1-12/+0
Yang Yang reported the following crash caused by requeueing a flush request in Kyber: [ 2.517297] Unable to handle kernel paging request at virtual address ffffffd8071c0b00 ... [ 2.517468] pc : clear_bit+0x18/0x2c [ 2.517502] lr : sbitmap_queue_clear+0x40/0x228 [ 2.517503] sp : ffffff800832bc60 pstate : 00c00145 ... [ 2.517599] Process ksoftirqd/5 (pid: 51, stack limit = 0xffffff8008328000) [ 2.517602] Call trace: [ 2.517606] clear_bit+0x18/0x2c [ 2.517619] kyber_finish_request+0x74/0x80 [ 2.517627] blk_mq_requeue_request+0x3c/0xc0 [ 2.517637] __scsi_queue_insert+0x11c/0x148 [ 2.517640] scsi_softirq_done+0x114/0x130 [ 2.517643] blk_done_softirq+0x7c/0xb0 [ 2.517651] __do_softirq+0x208/0x3bc [ 2.517657] run_ksoftirqd+0x34/0x60 [ 2.517663] smpboot_thread_fn+0x1c4/0x2c0 [ 2.517667] kthread+0x110/0x120 [ 2.517669] ret_from_fork+0x10/0x18 This happens because Kyber doesn't track flush requests, so kyber_finish_request() reads a garbage domain token. Only call the scheduler's requeue_request() hook if RQF_ELVPRIV is set (like we do for the finish_request() hook in blk_mq_free_request()). Now that we're handling it in blk-mq, also remove the check from BFQ. Reported-by: Yang Yang <yang.yang@vivo.com> Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-09-03blk-mq, elevator: Count requests per hctx to improve performanceKashyap Desai1-0/+5
High CPU utilization on "native_queued_spin_lock_slowpath" due to lock contention is possible for mq-deadline and bfq IO schedulers when nr_hw_queues is more than one. It is because kblockd work queue can submit IO from all online CPUs (through blk_mq_run_hw_queues()) even though only one hctx has pending commands. The elevator callback .has_work for mq-deadline and bfq scheduler considers pending work if there are any IOs on request queue but it does not account hctx context. Add a per-hctx 'elevator_queued' count to the hctx to avoid triggering the elevator even though there are no requests queued. [jpg: Relocated atomic_dec() in dd_dispatch_request(), update commit message per Kashyap] Signed-off-by: Kashyap Desai <kashyap.desai@broadcom.com> Signed-off-by: Hannes Reinecke <hare@suse.de> Signed-off-by: John Garry <john.garry@huawei.com> Tested-by: Douglas Gilbert <dgilbert@interlog.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-09-03blk-mq: Use pointers for blk_mq_tags bitmap tagsJohn Garry1-2/+2
Introduce pointers for the blk_mq_tags regular and reserved bitmap tags, with the goal of later being able to use a common shared tag bitmap across all HW contexts in a set. Signed-off-by: John Garry <john.garry@huawei.com> Tested-by: Don Brace<don.brace@microsemi.com> #SCSI resv cmds patches used Tested-by: Douglas Gilbert <dgilbert@interlog.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-08-23treewide: Use fallthrough pseudo-keywordGustavo A. R. Silva1-2/+2
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>
2020-07-31block: bfq-iosched: fix duplicated wordRandy Dunlap1-1/+1
Change "at at" to "at a". Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: linux-block@vger.kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-05-29blk-mq: remove the bio argument to ->prepare_requestChristoph Hellwig1-1/+1
None of the I/O schedulers actually needs it. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Daniel Wagner <dwagner@suse.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-05-09bdi: use bdi_dev_name() to get device nameYufen Yu1-2/+4
Use the common interface bdi_dev_name() to get device name. Signed-off-by: Yufen Yu <yuyufen@huawei.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Add missing <linux/backing-dev.h> include BFQ Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-03-21block, bfq: turn put_queue into release_process_ref in __bfq_bic_change_cgroupPaolo Valente1-2/+0
A bfq_put_queue() may be invoked in __bfq_bic_change_cgroup(). The goal of this put is to release a process reference to a bfq_queue. But process-reference releases may trigger also some extra operation, and, to this goal, are handled through bfq_release_process_ref(). So, turn the invocation of bfq_put_queue() into an invocation of bfq_release_process_ref(). Tested-by: cki-project@redhat.com Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-03-21block, bfq: fix use-after-free in bfq_idle_slice_timer_bodyZhiqiang Liu1-4/+12
In bfq_idle_slice_timer func, bfqq = bfqd->in_service_queue is not in bfqd-lock critical section. The bfqq, which is not equal to NULL in bfq_idle_slice_timer, may be freed after passing to bfq_idle_slice_timer_body. So we will access the freed memory. In addition, considering the bfqq may be in race, we should firstly check whether bfqq is in service before doing something on it in bfq_idle_slice_timer_body func. If the bfqq in race is not in service, it means the bfqq has been expired through __bfq_bfqq_expire func, and wait_request flags has been cleared in __bfq_bfqd_reset_in_service func. So we do not need to re-clear the wait_request of bfqq which is not in service. KASAN log is given as follows: [13058.354613] ================================================================== [13058.354640] BUG: KASAN: use-after-free in bfq_idle_slice_timer+0xac/0x290 [13058.354644] Read of size 8 at addr ffffa02cf3e63f78 by task fork13/19767 [13058.354646] [13058.354655] CPU: 96 PID: 19767 Comm: fork13 [13058.354661] Call trace: [13058.354667] dump_backtrace+0x0/0x310 [13058.354672] show_stack+0x28/0x38 [13058.354681] dump_stack+0xd8/0x108 [13058.354687] print_address_description+0x68/0x2d0 [13058.354690] kasan_report+0x124/0x2e0 [13058.354697] __asan_load8+0x88/0xb0 [13058.354702] bfq_idle_slice_timer+0xac/0x290 [13058.354707] __hrtimer_run_queues+0x298/0x8b8 [13058.354710] hrtimer_interrupt+0x1b8/0x678 [13058.354716] arch_timer_handler_phys+0x4c/0x78 [13058.354722] handle_percpu_devid_irq+0xf0/0x558 [13058.354731] generic_handle_irq+0x50/0x70 [13058.354735] __handle_domain_irq+0x94/0x110 [13058.354739] gic_handle_irq+0x8c/0x1b0 [13058.354742] el1_irq+0xb8/0x140 [13058.354748] do_wp_page+0x260/0xe28 [13058.354752] __handle_mm_fault+0x8ec/0x9b0 [13058.354756] handle_mm_fault+0x280/0x460 [13058.354762] do_page_fault+0x3ec/0x890 [13058.354765] do_mem_abort+0xc0/0x1b0 [13058.354768] el0_da+0x24/0x28 [13058.354770] [13058.354773] Allocated by task 19731: [13058.354780] kasan_kmalloc+0xe0/0x190 [13058.354784] kasan_slab_alloc+0x14/0x20 [13058.354788] kmem_cache_alloc_node+0x130/0x440 [13058.354793] bfq_get_queue+0x138/0x858 [13058.354797] bfq_get_bfqq_handle_split+0xd4/0x328 [13058.354801] bfq_init_rq+0x1f4/0x1180 [13058.354806] bfq_insert_requests+0x264/0x1c98 [13058.354811] blk_mq_sched_insert_requests+0x1c4/0x488 [13058.354818] blk_mq_flush_plug_list+0x2d4/0x6e0 [13058.354826] blk_flush_plug_list+0x230/0x548 [13058.354830] blk_finish_plug+0x60/0x80 [13058.354838] read_pages+0xec/0x2c0 [13058.354842] __do_page_cache_readahead+0x374/0x438 [13058.354846] ondemand_readahead+0x24c/0x6b0 [13058.354851] page_cache_sync_readahead+0x17c/0x2f8 [13058.354858] generic_file_buffered_read+0x588/0xc58 [13058.354862] generic_file_read_iter+0x1b4/0x278 [13058.354965] ext4_file_read_iter+0xa8/0x1d8 [ext4] [13058.354972] __vfs_read+0x238/0x320 [13058.354976] vfs_read+0xbc/0x1c0 [13058.354980] ksys_read+0xdc/0x1b8 [13058.354984] __arm64_sys_read+0x50/0x60 [13058.354990] el0_svc_common+0xb4/0x1d8 [13058.354994] el0_svc_handler+0x50/0xa8 [13058.354998] el0_svc+0x8/0xc [13058.354999] [13058.355001] Freed by task 19731: [13058.355007] __kasan_slab_free+0x120/0x228 [13058.355010] kasan_slab_free+0x10/0x18 [13058.355014] kmem_cache_free+0x288/0x3f0 [13058.355018] bfq_put_queue+0x134/0x208 [13058.355022] bfq_exit_icq_bfqq+0x164/0x348 [13058.355026] bfq_exit_icq+0x28/0x40 [13058.355030] ioc_exit_icq+0xa0/0x150 [13058.355035] put_io_context_active+0x250/0x438 [13058.355038] exit_io_context+0xd0/0x138 [13058.355045] do_exit+0x734/0xc58 [13058.355050] do_group_exit+0x78/0x220 [13058.355054] __wake_up_parent+0x0/0x50 [13058.355058] el0_svc_common+0xb4/0x1d8 [13058.355062] el0_svc_handler+0x50/0xa8 [13058.355066] el0_svc+0x8/0xc [13058.355067] [13058.355071] The buggy address belongs to the object at ffffa02cf3e63e70#012 which belongs to the cache bfq_queue of size 464 [13058.355075] The buggy address is located 264 bytes inside of#012 464-byte region [ffffa02cf3e63e70, ffffa02cf3e64040) [13058.355077] The buggy address belongs to the page: [13058.355083] page:ffff7e80b3cf9800 count:1 mapcount:0 mapping:ffff802db5c90780 index:0xffffa02cf3e606f0 compound_mapcount: 0 [13058.366175] flags: 0x2ffffe0000008100(slab|head) [13058.370781] raw: 2ffffe0000008100 ffff7e80b53b1408 ffffa02d730c1c90 ffff802db5c90780 [13058.370787] raw: ffffa02cf3e606f0 0000000000370023 00000001ffffffff 0000000000000000 [13058.370789] page dumped because: kasan: bad access detected [13058.370791] [13058.370792] Memory state around the buggy address: [13058.370797] ffffa02cf3e63e00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fb fb [13058.370801] ffffa02cf3e63e80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [13058.370805] >ffffa02cf3e63f00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [13058.370808] ^ [13058.370811] ffffa02cf3e63f80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [13058.370815] ffffa02cf3e64000: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc [13058.370817] ================================================================== [13058.370820] Disabling lock debugging due to kernel taint Here, we directly pass the bfqd to bfq_idle_slice_timer_body func. -- V2->V3: rewrite the comment as suggested by Paolo Valente V1->V2: add one comment, and add Fixes and Reported-by tag. Fixes: aee69d78d ("block, bfq: introduce the BFQ-v0 I/O scheduler as an extra scheduler") Acked-by: Paolo Valente <paolo.valente@linaro.org> Reported-by: Wang Wang <wangwang2@huawei.com> Signed-off-by: Zhiqiang Liu <liuzhiqiang26@huawei.com> Signed-off-by: Feilong Lin <linfeilong@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-02-03block, bfq: clarify the goal of bfq_split_bfqq()Paolo Valente1-0/+2
The exact, general goal of the function bfq_split_bfqq() is not that apparent. Add a comment to make it clear. Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-02-03block, bfq: remove ifdefs from around gets/puts of bfq groupsPaolo Valente1-5/+1
ifdefs around gets and puts of bfq groups reduce readability, remove them. Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Reported-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-02-03block, bfq: extend incomplete name of field on_stPaolo Valente1-1/+1
The flag on_st in the bfq_entity data structure is true if the entity is on a service tree or is in service. Yet the name of the field, confusingly, does not mention the second, very important case. Extend the name to mention the second case too. Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-02-03block, bfq: do not insert oom queue into position treePaolo Valente1-0/+4
BFQ maintains an ordered list, implemented with an RB tree, of head-request positions of non-empty bfq_queues. This position tree, inherited from CFQ, is used to find bfq_queues that contain I/O close to each other. BFQ merges these bfq_queues into a single shared queue, if this boosts throughput on the device at hand. There is however a special-purpose bfq_queue that does not participate in queue merging, the oom bfq_queue. Yet, also this bfq_queue could be wrongly added to the position tree. So bfqq_find_close() could return the oom bfq_queue, which is a source of further troubles in an out-of-memory situation. This commit prevents the oom bfq_queue from being inserted into the position tree. Tested-by: Patrick Dung <patdung100@gmail.com> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-02-03block, bfq: do not plug I/O for bfq_queues with no proc refsPaolo Valente1-0/+12
Commit 478de3380c1c ("block, bfq: deschedule empty bfq_queues not referred by any process") fixed commit 3726112ec731 ("block, bfq: re-schedule empty queues if they deserve I/O plugging") by descheduling an empty bfq_queue when it remains with not process reference. Yet, this still left a case uncovered: an empty bfq_queue with not process reference that remains in service. This happens for an in-service sync bfq_queue that is deemed to deserve I/O-dispatch plugging when it remains empty. Yet no new requests will arrive for such a bfq_queue if no process sends requests to it any longer. Even worse, the bfq_queue may happen to be prematurely freed while still in service (because there may remain no reference to it any longer). This commit solves this problem by preventing I/O dispatch from being plugged for the in-service bfq_queue, if the latter has no process reference (the bfq_queue is then prevented from remaining in service). Fixes: 3726112ec731 ("block, bfq: re-schedule empty queues if they deserve I/O plugging") Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Reported-by: Patrick Dung <patdung100@gmail.com> Tested-by: Patrick Dung <patdung100@gmail.com> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-01-22block/bfq: remove unused bfq_class_rt which never usedAlex Shi1-1/+0
This macro is never used after introduced from commit aee69d78dec0 ("block, bfq: introduce the BFQ-v0 I/O scheduler as an extra scheduler") Better to remove it. Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> Cc: Paolo Valente <paolo.valente@linaro.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: linux-block@vger.kernel.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-11-25Merge tag 'for-5.5/block-20191121' of git://git.kernel.dk/linux-blockLinus Torvalds1-0/+4
Pull core block updates from Jens Axboe: "Due to more granular branches, this one is small and will be followed with other core branches that add specific features. I meant to just have a core and drivers branch, but external dependencies we ended up adding a few more that are also core. The changes are: - Fixes and improvements for the zoned device support (Ajay, Damien) - sed-opal table writing and datastore UID (Revanth) - blk-cgroup (and bfq) blk-cgroup stat fixes (Tejun) - Improvements to the block stats tracking (Pavel) - Fix for overruning sysfs buffer for large number of CPUs (Ming) - Optimization for small IO (Ming, Christoph) - Fix typo in RWH lifetime hint (Eugene) - Dead code removal and documentation (Bart) - Reduction in memory usage for queue and tag set (Bart) - Kerneldoc header documentation (André) - Device/partition revalidation fixes (Jan) - Stats tracking for flush requests (Konstantin) - Various other little fixes here and there (et al)" * tag 'for-5.5/block-20191121' of git://git.kernel.dk/linux-block: (48 commits) Revert "block: split bio if the only bvec's length is > SZ_4K" block: add iostat counters for flush requests block,bfq: Skip tracing hooks if possible block: sed-opal: Introduce SUM_SET_LIST parameter and append it using 'add_token_u64' blk-cgroup: cgroup_rstat_updated() shouldn't be called on cgroup1 block: Don't disable interrupts in trigger_softirq() sbitmap: Delete sbitmap_any_bit_clear() blk-mq: Delete blk_mq_has_free_tags() and blk_mq_can_queue() block: split bio if the only bvec's length is > SZ_4K block: still try to split bio if the bvec crosses pages blk-cgroup: separate out blkg_rwstat under CONFIG_BLK_CGROUP_RWSTAT blk-cgroup: reimplement basic IO stats using cgroup rstat blk-cgroup: remove now unused blkg_print_stat_{bytes|ios}_recursive() blk-throtl: stop using blkg->stat_bytes and ->stat_ios bfq-iosched: stop using blkg->stat_bytes and ->stat_ios bfq-iosched: relocate bfqg_*rwstat*() helpers block: add zone open, close and finish ioctl support block: add zone open, close and finish operations block: Simplify REQ_OP_ZONE_RESET_ALL handling block: Remove REQ_OP_ZONE_RESET plugging ...
2019-11-14block, bfq: deschedule empty bfq_queues not referred by any processPaolo Valente1-6/+26
Since commit 3726112ec731 ("block, bfq: re-schedule empty queues if they deserve I/O plugging"), to prevent the service guarantees of a bfq_queue from being violated, the bfq_queue may be left busy, i.e., scheduled for service, even if empty (see comments in __bfq_bfqq_expire() for details). But, if no process will send requests to the bfq_queue any longer, then there is no point in keeping the bfq_queue scheduled for service. In addition, keeping the bfq_queue scheduled for service, but with no process reference any longer, may cause the bfq_queue to be freed when descheduled from service. But this is assumed to never happen, and causes a UAF if it happens. This, in turn, caused crashes [1, 2]. This commit fixes this issue by descheduling an empty bfq_queue when it remains with not process reference. [1] https://bugzilla.redhat.com/show_bug.cgi?id=1767539 [2] https://bugzilla.kernel.org/show_bug.cgi?id=205447 Fixes: 3726112ec731 ("block, bfq: re-schedule empty queues if they deserve I/O plugging") Reported-by: Chris Evich <cevich@redhat.com> Reported-by: Patrick Dung <patdung100@gmail.com> Reported-by: Thorsten Schubert <tschubert@bafh.org> Tested-by: Thorsten Schubert <tschubert@bafh.org> Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name> Signed-off-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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