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* treewide: use prandom_u32_max() when possible, part 2Jason A. Donenfeld2022-10-111-1/+1
| | | | | | | | | | | | | | Rather than incurring a division or requesting too many random bytes for the given range, use the prandom_u32_max() function, which only takes the minimum required bytes from the RNG and avoids divisions. This was done by hand, covering things that coccinelle could not do on its own. Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Yury Norov <yury.norov@gmail.com> Reviewed-by: Jan Kara <jack@suse.cz> # for ext2, ext4, and sbitmap Acked-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
* treewide: use prandom_u32_max() when possible, part 1Jason A. Donenfeld2022-10-111-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Rather than incurring a division or requesting too many random bytes for the given range, use the prandom_u32_max() function, which only takes the minimum required bytes from the RNG and avoids divisions. This was done mechanically with this coccinelle script: @basic@ expression E; type T; identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32"; typedef u64; @@ ( - ((T)get_random_u32() % (E)) + prandom_u32_max(E) | - ((T)get_random_u32() & ((E) - 1)) + prandom_u32_max(E * XXX_MAKE_SURE_E_IS_POW2) | - ((u64)(E) * get_random_u32() >> 32) + prandom_u32_max(E) | - ((T)get_random_u32() & ~PAGE_MASK) + prandom_u32_max(PAGE_SIZE) ) @multi_line@ identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32"; identifier RAND; expression E; @@ - RAND = get_random_u32(); ... when != RAND - RAND %= (E); + RAND = prandom_u32_max(E); // Find a potential literal @literal_mask@ expression LITERAL; type T; identifier get_random_u32 =~ "get_random_int|prandom_u32|get_random_u32"; position p; @@ ((T)get_random_u32()@p & (LITERAL)) // Add one to the literal. @script:python add_one@ literal << literal_mask.LITERAL; RESULT; @@ value = None if literal.startswith('0x'): value = int(literal, 16) elif literal[0] in '123456789': value = int(literal, 10) if value is None: print("I don't know how to handle %s" % (literal)) cocci.include_match(False) elif value == 2**32 - 1 or value == 2**31 - 1 or value == 2**24 - 1 or value == 2**16 - 1 or value == 2**8 - 1: print("Skipping 0x%x for cleanup elsewhere" % (value)) cocci.include_match(False) elif value & (value + 1) != 0: print("Skipping 0x%x because it's not a power of two minus one" % (value)) cocci.include_match(False) elif literal.startswith('0x'): coccinelle.RESULT = cocci.make_expr("0x%x" % (value + 1)) else: coccinelle.RESULT = cocci.make_expr("%d" % (value + 1)) // Replace the literal mask with the calculated result. @plus_one@ expression literal_mask.LITERAL; position literal_mask.p; expression add_one.RESULT; identifier FUNC; @@ - (FUNC()@p & (LITERAL)) + prandom_u32_max(RESULT) @collapse_ret@ type T; identifier VAR; expression E; @@ { - T VAR; - VAR = (E); - return VAR; + return E; } @drop_var@ type T; identifier VAR; @@ { - T VAR; ... when != VAR } Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Reviewed-by: Kees Cook <keescook@chromium.org> Reviewed-by: Yury Norov <yury.norov@gmail.com> Reviewed-by: KP Singh <kpsingh@kernel.org> Reviewed-by: Jan Kara <jack@suse.cz> # for ext4 and sbitmap Reviewed-by: Christoph Böhmwalder <christoph.boehmwalder@linbit.com> # for drbd Acked-by: Jakub Kicinski <kuba@kernel.org> Acked-by: Heiko Carstens <hca@linux.ibm.com> # for s390 Acked-by: Ulf Hansson <ulf.hansson@linaro.org> # for mmc Acked-by: Darrick J. Wong <djwong@kernel.org> # for xfs Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
* sbitmap: fix lockup while swappingHugh Dickins2022-09-291-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Commit 4acb83417cad ("sbitmap: fix batched wait_cnt accounting") is a big improvement: without it, I had to revert to before commit 040b83fcecfb ("sbitmap: fix possible io hung due to lost wakeup") to avoid the high system time and freezes which that had introduced. Now okay on the NVME laptop, but 4acb83417cad is a disaster for heavy swapping (kernel builds in low memory) on another: soon locking up in sbitmap_queue_wake_up() (into which __sbq_wake_up() is inlined), cycling around with waitqueue_active() but wait_cnt 0 . Here is a backtrace, showing the common pattern of outer sbitmap_queue_wake_up() interrupted before setting wait_cnt 0 back to wake_batch (in some cases other CPUs are idle, in other cases they're spinning for a lock in dd_bio_merge()): sbitmap_queue_wake_up < sbitmap_queue_clear < blk_mq_put_tag < __blk_mq_free_request < blk_mq_free_request < __blk_mq_end_request < scsi_end_request < scsi_io_completion < scsi_finish_command < scsi_complete < blk_complete_reqs < blk_done_softirq < __do_softirq < __irq_exit_rcu < irq_exit_rcu < common_interrupt < asm_common_interrupt < _raw_spin_unlock_irqrestore < __wake_up_common_lock < __wake_up < sbitmap_queue_wake_up < sbitmap_queue_clear < blk_mq_put_tag < __blk_mq_free_request < blk_mq_free_request < dd_bio_merge < blk_mq_sched_bio_merge < blk_mq_attempt_bio_merge < blk_mq_submit_bio < __submit_bio < submit_bio_noacct_nocheck < submit_bio_noacct < submit_bio < __swap_writepage < swap_writepage < pageout < shrink_folio_list < evict_folios < lru_gen_shrink_lruvec < shrink_lruvec < shrink_node < do_try_to_free_pages < try_to_free_pages < __alloc_pages_slowpath < __alloc_pages < folio_alloc < vma_alloc_folio < do_anonymous_page < __handle_mm_fault < handle_mm_fault < do_user_addr_fault < exc_page_fault < asm_exc_page_fault See how the process-context sbitmap_queue_wake_up() has been interrupted, after bringing wait_cnt down to 0 (and in this example, after doing its wakeups), before advancing wake_index and refilling wake_cnt: an interrupt-context sbitmap_queue_wake_up() of the same sbq gets stuck. I have almost no grasp of all the possible sbitmap races, and their consequences: but __sbq_wake_up() can do nothing useful while wait_cnt 0, so it is better if sbq_wake_ptr() skips on to the next ws in that case: which fixes the lockup and shows no adverse consequence for me. The check for wait_cnt being 0 is obviously racy, and ultimately can lead to lost wakeups: for example, when there is only a single waitqueue with waiters. However, lost wakeups are unlikely to matter in these cases, and a proper fix requires redesign (and benchmarking) of the batched wakeup code: so let's plug the hole with this bandaid for now. Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Keith Busch <kbusch@kernel.org> Link: https://lore.kernel.org/r/9c2038a7-cdc5-5ee-854c-fbc6168bf16@google.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: fix batched wait_cnt accountingKeith Busch2022-09-121-14/+23
| | | | | | | | | | | Batched completions can clear multiple bits, but we're only decrementing the wait_cnt by one each time. This can cause waiters to never be woken, stalling IO. Use the batched count instead. Link: https://bugzilla.kernel.org/show_bug.cgi?id=215679 Signed-off-by: Keith Busch <kbusch@kernel.org> Link: https://lore.kernel.org/r/20220909184022.1709476-1-kbusch@fb.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: Use atomic_long_try_cmpxchg in __sbitmap_queue_get_batchUros Bizjak2022-09-081-5/+5
| | | | | | | | | | | | | | | | | | | Use atomic_long_try_cmpxchg instead of atomic_long_cmpxchg (*ptr, old, new) == old in __sbitmap_queue_get_batch. x86 CMPXCHG instruction returns success in ZF flag, so this change saves a compare after cmpxchg (and related move instruction in front of cmpxchg). Also, atomic_long_cmpxchg implicitly assigns old *ptr value to "old" when cmpxchg fails, enabling further code simplifications, e.g. an extra memory read can be avoided in the loop. No functional change intended. Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Uros Bizjak <ubizjak@gmail.com> Link: https://lore.kernel.org/r/20220908151200.9993-1-ubizjak@gmail.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: Avoid leaving waitqueue in invalid state in __sbq_wake_up()Jan Kara2022-09-081-3/+15
| | | | | | | | | | | | | | | | When __sbq_wake_up() decrements wait_cnt to 0 but races with someone else waking the waiter on the waitqueue (so the waitqueue becomes empty), it exits without reseting wait_cnt to wake_batch number. Once wait_cnt is 0, nobody will ever reset the wait_cnt or wake the new waiters resulting in possible deadlocks or busyloops. Fix the problem by making sure we reset wait_cnt even if we didn't wake up anybody in the end. Fixes: 040b83fcecfb ("sbitmap: fix possible io hung due to lost wakeup") Reported-by: Keith Busch <kbusch@kernel.org> Signed-off-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20220908130937.2795-1-jack@suse.cz Signed-off-by: Jens Axboe <axboe@kernel.dk>
* Revert "sbitmap: fix batched wait_cnt accounting"Jens Axboe2022-09-041-17/+14
| | | | | | | | | | | | This reverts commit 16ede66973c84f890c03584f79158dd5b2d725f5. This is causing issues with CPU stalls on my test box, revert it for now until we understand what is going on. It looks like infinite looping off sbitmap_queue_wake_up(), but hard to tell with a lot of CPUs hitting this issue and the console scrolling infinitely. Link: https://lore.kernel.org/linux-block/e742813b-ce5c-0d58-205b-1626f639b1bd@kernel.dk/ Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: fix batched wait_cnt accountingKeith Busch2022-09-011-14/+17
| | | | | | | | | | | Batched completions can clear multiple bits, but we're only decrementing the wait_cnt by one each time. This can cause waiters to never be woken, stalling IO. Use the batched count instead. Link: https://bugzilla.kernel.org/show_bug.cgi?id=215679 Signed-off-by: Keith Busch <kbusch@kernel.org> Link: https://lore.kernel.org/r/20220825145312.1217900-1-kbusch@fb.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: remove unnecessary code in __sbitmap_queue_get_batchLiu Song2022-08-261-3/+2
| | | | | | | | | If "nr + nr_tags <= map_depth", then the value of nr_tags will not be greater than map_depth, so no additional comparison is required. Signed-off-by: Liu Song <liusong@linux.alibaba.com> Link: https://lore.kernel.org/r/1661483653-27326-1-git-send-email-liusong@linux.alibaba.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: fix possible io hung due to lost wakeupYu Kuai2022-08-231-22/+33
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There are two problems can lead to lost wakeup: 1) invalid wakeup on the wrong waitqueue: For example, 2 * wake_batch tags are put, while only wake_batch threads are woken: __sbq_wake_up atomic_cmpxchg -> reset wait_cnt __sbq_wake_up -> decrease wait_cnt ... __sbq_wake_up -> wait_cnt is decreased to 0 again atomic_cmpxchg sbq_index_atomic_inc -> increase wake_index wake_up_nr -> wake up and waitqueue might be empty sbq_index_atomic_inc -> increase again, one waitqueue is skipped wake_up_nr -> invalid wake up because old wakequeue might be empty To fix the problem, increasing 'wake_index' before resetting 'wait_cnt'. 2) 'wait_cnt' can be decreased while waitqueue is empty As pointed out by Jan Kara, following race is possible: CPU1 CPU2 __sbq_wake_up __sbq_wake_up sbq_wake_ptr() sbq_wake_ptr() -> the same wait_cnt = atomic_dec_return() /* decreased to 0 */ sbq_index_atomic_inc() /* move to next waitqueue */ atomic_set() /* reset wait_cnt */ wake_up_nr() /* wake up on the old waitqueue */ wait_cnt = atomic_dec_return() /* * decrease wait_cnt in the old * waitqueue, while it can be * empty. */ Fix the problem by waking up before updating 'wake_index' and 'wait_cnt'. With this patch, noted that 'wait_cnt' is still decreased in the old empty waitqueue, however, the wakeup is redirected to a active waitqueue, and the extra decrement on the old empty waitqueue is not handled. Fixes: 88459642cba4 ("blk-mq: abstract tag allocation out into sbitmap library") Signed-off-by: Yu Kuai <yukuai3@huawei.com> Reviewed-by: Jan Kara <jack@suse.cz> Link: https://lore.kernel.org/r/20220803121504.212071-1-yukuai1@huaweicloud.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
* lib/sbitmap: Fix invalid loop in __sbitmap_queue_get_batch()wuchi2022-06-251-1/+4
| | | | | | | | | | | | 1. Getting next index before continue branch. 2. Checking free bits when setting the target bits. Otherwise, it may reuse the busying bits. Signed-off-by: wuchi <wuchi.zero@gmail.com> Reviewed-by: Martin Wilck <mwilck@suse.com> Link: https://lore.kernel.org/r/20220605145835.26916-1-wuchi.zero@gmail.com Fixes: 9672b0d43782 ("sbitmap: add __sbitmap_queue_get_batch()") Signed-off-by: Jens Axboe <axboe@kernel.dk>
* lib/sbitmap: allocate sb->map via kvzalloc_nodeMing Lei2022-03-211-1/+1
| | | | | | | | | | | | | | | | | | | | sbitmap has been used in scsi for replacing atomic operations on sdev->device_busy, so IOPS on some fast scsi storage can be improved. However, sdev->device_busy can be changed in fast path, so we have to allocate the sb->map statically. sdev->device_busy has been capped to 1024, but some drivers may configure the default depth as < 8, then cause each sbitmap word to hold only one bit. Finally 1024 * 128( sizeof(sbitmap_word)) bytes is needed for sb->map, given it is order 5 allocation, sometimes it may fail. Avoid the issue by using kvzalloc_node() for allocating sb->map. Cc: Ewan D. Milne <emilne@redhat.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com> Link: https://lore.kernel.org/r/20220316012708.354668-1-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: Delete old sbitmap_queue_get_shallow()John Garry2022-02-081-3/+3
| | | | | | | | | | | | | Since __sbitmap_queue_get_shallow() was introduced in commit c05e66733788 ("sbitmap: add sbitmap_get_shallow() operation"), it has not been used. Delete __sbitmap_queue_get_shallow() and rename public __sbitmap_queue_get_shallow() -> sbitmap_queue_get_shallow() as it is odd to have public __foo but no foo at all. Signed-off-by: John Garry <john.garry@huawei.com> Link: https://lore.kernel.org/r/1644322024-105340-1-git-send-email-john.garry@huawei.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
* lib/sbitmap: kill 'depth' from sbitmap_wordMing Lei2022-02-081-20/+14
| | | | | | | | | | | | | | | | | | | | | | Only the last sbitmap_word can have different depth, and all the others must have same depth of 1U << sb->shift, so not necessary to store it in sbitmap_word, and it can be retrieved easily and efficiently by adding one internal helper of __map_depth(sb, index). Remove 'depth' field from sbitmap_word, then the annotation of ____cacheline_aligned_in_smp for 'word' isn't needed any more. Not see performance effect when running high parallel IOPS test on null_blk. This way saves us one cacheline(usually 64 words) per each sbitmap_word. Cc: Martin Wilck <martin.wilck@suse.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Martin Wilck <mwilck@suse.com> Reviewed-by: John Garry <john.garry@huawei.com> Link: https://lore.kernel.org/r/20220110072945.347535-1-ming.lei@redhat.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blk-mq: Fix wrong wakeup batch configuration which will cause hangLaibin Qiu2022-01-271-2/+6
| | | | | | | | | | | | | | | | | | | | | | Commit 180dccb0dba4f ("blk-mq: fix tag_get wait task can't be awakened") will recalculate wake_batch when incrementing or decrementing active_queues to avoid wake_batch > hctx_max_depth. At the same time, in order to not affect performance as much as possible, the minimum wakeup batch is set to 4. But when the QD is small (such as QD=1), if inc or dec active_queues increases wakeup batch, that can lead to a hang: Fix this problem with the following strategies: QD : >= 32 | < 32 --------------------------------- wakeup batch: 8~4 | 3~1 Fixes: 180dccb0dba4f ("blk-mq: fix tag_get wait task can't be awakened") Link: https://lore.kernel.org/linux-block/78cafe94-a787-e006-8851-69906f0c2128@huawei.com/T/#t Reported-by: Alex Xu (Hello71) <alex_y_xu@yahoo.ca> Signed-off-by: Laibin Qiu <qiulaibin@huawei.com> Tested-by: Alex Xu (Hello71) <alex_y_xu@yahoo.ca> Link: https://lore.kernel.org/r/20220127100047.1763746-1-qiulaibin@huawei.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
* blk-mq: fix tag_get wait task can't be awakenedLaibin Qiu2022-01-131-3/+22
| | | | | | | | | | | | | | | | | | | | | | | In case of shared tags, there might be more than one hctx which allocates from the same tags, and each hctx is limited to allocate at most: hctx_max_depth = max((bt->sb.depth + users - 1) / users, 4U); tag idle detection is lazy, and may be delayed for 30sec, so there could be just one real active hctx(queue) but all others are actually idle and still accounted as active because of the lazy idle detection. Then if wake_batch is > hctx_max_depth, driver tag allocation may wait forever on this real active hctx. Fix this by recalculating wake_batch when inc or dec active_queues. Fixes: 0d2602ca30e41 ("blk-mq: improve support for shared tags maps") Suggested-by: Ming Lei <ming.lei@redhat.com> Suggested-by: John Garry <john.garry@huawei.com> Signed-off-by: Laibin Qiu <qiulaibin@huawei.com> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Link: https://lore.kernel.org/r/20220113025536.1479653-1-qiulaibin@huawei.com Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: silence data race warningJens Axboe2021-10-251-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | KCSAN complaints about the sbitmap hint update: ================================================================== BUG: KCSAN: data-race in sbitmap_queue_clear / sbitmap_queue_clear write to 0xffffe8ffffd145b8 of 4 bytes by interrupt on cpu 1: sbitmap_queue_clear+0xca/0xf0 lib/sbitmap.c:606 blk_mq_put_tag+0x82/0x90 __blk_mq_free_request+0x114/0x180 block/blk-mq.c:507 blk_mq_free_request+0x2c8/0x340 block/blk-mq.c:541 __blk_mq_end_request+0x214/0x230 block/blk-mq.c:565 blk_mq_end_request+0x37/0x50 block/blk-mq.c:574 lo_complete_rq+0xca/0x170 drivers/block/loop.c:541 blk_complete_reqs block/blk-mq.c:584 [inline] blk_done_softirq+0x69/0x90 block/blk-mq.c:589 __do_softirq+0x12c/0x26e kernel/softirq.c:558 run_ksoftirqd+0x13/0x20 kernel/softirq.c:920 smpboot_thread_fn+0x22f/0x330 kernel/smpboot.c:164 kthread+0x262/0x280 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 write to 0xffffe8ffffd145b8 of 4 bytes by interrupt on cpu 0: sbitmap_queue_clear+0xca/0xf0 lib/sbitmap.c:606 blk_mq_put_tag+0x82/0x90 __blk_mq_free_request+0x114/0x180 block/blk-mq.c:507 blk_mq_free_request+0x2c8/0x340 block/blk-mq.c:541 __blk_mq_end_request+0x214/0x230 block/blk-mq.c:565 blk_mq_end_request+0x37/0x50 block/blk-mq.c:574 lo_complete_rq+0xca/0x170 drivers/block/loop.c:541 blk_complete_reqs block/blk-mq.c:584 [inline] blk_done_softirq+0x69/0x90 block/blk-mq.c:589 __do_softirq+0x12c/0x26e kernel/softirq.c:558 run_ksoftirqd+0x13/0x20 kernel/softirq.c:920 smpboot_thread_fn+0x22f/0x330 kernel/smpboot.c:164 kthread+0x262/0x280 kernel/kthread.c:319 ret_from_fork+0x1f/0x30 value changed: 0x00000035 -> 0x00000044 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 10 Comm: ksoftirqd/0 Not tainted 5.15.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ================================================================== which is a data race, but not an important one. This is just updating the percpu alloc hint, and the reader of that hint doesn't ever require it to be valid. Just annotate it with data_race() to silence this one. Reported-by: syzbot+4f8bfd804b4a1f95b8f6@syzkaller.appspotmail.com Acked-by: Marco Elver <elver@google.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: add helper to clear a batch of tagsJens Axboe2021-10-181-3/+41
| | | | | | | sbitmap currently only supports clearing tags one-by-one, add a helper that allows the caller to pass in an array of tags to clear. Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: add __sbitmap_queue_get_batch()Jens Axboe2021-10-181-0/+51
| | | | | | | | | | | | | | | | | | | The block layer tag allocation batching still calls into sbitmap to get each tag, but we can improve on that. Add __sbitmap_queue_get_batch(), which returns a mask of tags all at once, along with an offset for those tags. An example return would be 0xff, where bits 0..7 are set, with tag_offset == 128. The valid tags in this case would be 128..135. A batch is specific to an individual sbitmap_map, hence it cannot be larger than that. The requested number of tags is automatically reduced to the max that can be satisfied with a single map. On failure, 0 is returned. Caller should fall back to single tag allocation at that point/ Signed-off-by: Jens Axboe <axboe@kernel.dk>
* lib: fix spelling mistakesZhen Lei2021-07-081-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Fix some spelling mistakes in comments: permanentely ==> permanently wont ==> won't remaning ==> remaining succed ==> succeed shouldnt ==> shouldn't alpha-numeric ==> alphanumeric storeing ==> storing funtion ==> function documenation ==> documentation Determin ==> Determine intepreted ==> interpreted ammount ==> amount obious ==> obvious interupts ==> interrupts occured ==> occurred asssociated ==> associated taking into acount ==> taking into account squence ==> sequence stil ==> still contiguos ==> contiguous matchs ==> matches Link: https://lkml.kernel.org/r/20210607072555.12416-1-thunder.leizhen@huawei.com Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* scsi: sbitmap: Add sbitmap_calculate_shift() helperMing Lei2021-03-041-13/+3
| | | | | | | | | | | | | | | Move code for calculating default shift into a public helper which can be used by SCSI. Link: https://lore.kernel.org/r/20210122023317.687987-7-ming.lei@redhat.com Cc: Omar Sandoval <osandov@fb.com> Cc: Kashyap Desai <kashyap.desai@broadcom.com> Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com> Cc: Ewan D. Milne <emilne@redhat.com> Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
* scsi: sbitmap: Export sbitmap_weightMing Lei2021-03-041-5/+6
| | | | | | | | | | | | | | | | | | | SCSI's .device_busy will be converted to sbitmap and sbitmap_weight is needed. Export the helper. The only existing user of sbitmap_weight() uses it to find out how many bits are set and not cleared. Align sbitmap_weight() meaning with this usage model. Link: https://lore.kernel.org/r/20210122023317.687987-6-ming.lei@redhat.com Cc: Omar Sandoval <osandov@fb.com> Cc: Kashyap Desai <kashyap.desai@broadcom.com> Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com> Cc: Ewan D. Milne <emilne@redhat.com> Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
* scsi: sbitmap: Move allocation hint into sbitmapMing Lei2021-03-041-46/+66
| | | | | | | | | | | | | | | | | | | | | | | | Allocation hint should have belonged to sbitmap. Also, when sbitmap's depth is high and there is no need to use mulitple wakeup queues, user can benefit from percpu allocation hint too. Move allocation hint into sbitmap, then SCSI device queue can benefit from allocation hint when converting to plain sbitmap. Convert vhost/scsi.c to use sbitmap allocation with percpu alloc hint. This is more efficient than the previous approach. Link: https://lore.kernel.org/r/20210122023317.687987-5-ming.lei@redhat.com Cc: Omar Sandoval <osandov@fb.com> Cc: Kashyap Desai <kashyap.desai@broadcom.com> Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com> Cc: Ewan D. Milne <emilne@redhat.com> Cc: Mike Christie <michael.christie@oracle.com> Cc: virtualization@lists.linux-foundation.org Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
* scsi: sbitmap: Add helpers for updating allocation hintMing Lei2021-03-041-39/+54
| | | | | | | | | | | | | | | | | | Add helpers for updating allocation hint so that we can avoid duplicate code. Prepare for moving allocation hint into sbitmap. Link: https://lore.kernel.org/r/20210122023317.687987-4-ming.lei@redhat.com Cc: Omar Sandoval <osandov@fb.com> Cc: Kashyap Desai <kashyap.desai@broadcom.com> Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com> Cc: Ewan D. Milne <emilne@redhat.com> Cc: Hannes Reinecke <hare@suse.de> Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
* scsi: sbitmap: Maintain allocation round_robin in sbitmapMing Lei2021-03-041-14/+14
| | | | | | | | | | | | | | | | | | Currently the allocation round_robin info is maintained by sbitmap_queue. However, bit allocation really belongs to sbitmap. Move it there. Link: https://lore.kernel.org/r/20210122023317.687987-3-ming.lei@redhat.com Cc: Omar Sandoval <osandov@fb.com> Cc: Kashyap Desai <kashyap.desai@broadcom.com> Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com> Cc: Ewan D. Milne <emilne@redhat.com> Cc: Hannes Reinecke <hare@suse.de> Cc: virtualization@lists.linux-foundation.org Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com> Reviewed-by: Hannes Reinecke <hare@suse.de> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
* sbitmap: simplify wrap checkPavel Begunkov2020-12-071-3/+5
| | | | | | | | | __sbitmap_get_word() doesn't warp if it's starting from the beginning (i.e. initial hint is 0). Instead of stashing the original hint just set @wrap accordingly. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: replace CAS with atomic andPavel Begunkov2020-12-071-5/+3
| | | | | | | | | | | | | | | sbitmap_deferred_clear() does CAS loop to propagate cleared bits, replace it with equivalent atomic bitwise and. That's slightly faster and makes wait-free instead of lock-free as before. The atomic can be relaxed (i.e. barrier-less) because following sbitmap_get*() deal with synchronisation, see comments in sbitmap_queue_clear(). It's ok to cast to atomic_long_t, that's what bitops/lock.h does. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: remove swap_lockPavel Begunkov2020-12-071-11/+3
| | | | | | | | | | | | | map->swap_lock protects map->cleared from concurrent modification, however sbitmap_deferred_clear() is already atomically drains it, so it's guaranteed to not loose bits on concurrent sbitmap_deferred_clear(). A one threaded tag heavy test on top of nullbk showed ~1.5% t-put increase, and 3% -> 1% cycle reduction of sbitmap_get() according to perf. Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: optimise sbitmap_deferred_clear()Pavel Begunkov2020-12-071-12/+12
| | | | | | | | | | | | Because of spinlocks and atomics sbitmap_deferred_clear() have to reload &sb->map[index] on each access even though the map address won't change. Pass in sbitmap_word instead of {sb, index}, so it's cached in a variable. It also improves code generation of sbitmap_find_bit_in_index(). Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Reviewed-by: John Garry <john.garry@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: Consider cleared bits in sbitmap_bitmap_show()John Garry2020-07-011-0/+3
| | | | | | | | | | | | | sbitmap works by maintaining separate bitmaps of set and cleared bits. The set bits are cleared in a batch, to save the burden of continuously locking the "word" map to unset. sbitmap_bitmap_show() only shows the set bits (in "word"), which is not too much use, so mask out the cleared bits. Fixes: ea86ea2cdced ("sbitmap: ammortize cost of clearing bits") Signed-off-by: John Garry <john.garry@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: only queue kyber's wait callback if not already activeDavid Jeffery2019-12-201-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Under heavy loads where the kyber I/O scheduler hits the token limits for its scheduling domains, kyber can become stuck. When active requests complete, kyber may not be woken up leaving the I/O requests in kyber stuck. This stuck state is due to a race condition with kyber and the sbitmap functions it uses to run a callback when enough requests have completed. The running of a sbt_wait callback can race with the attempt to insert the sbt_wait. Since sbitmap_del_wait_queue removes the sbt_wait from the list first then sets the sbq field to NULL, kyber can see the item as not on a list but the call to sbitmap_add_wait_queue will see sbq as non-NULL. This results in the sbt_wait being inserted onto the wait list but ws_active doesn't get incremented. So the sbitmap queue does not know there is a waiter on a wait list. Since sbitmap doesn't think there is a waiter, kyber may never be informed that there are domain tokens available and the I/O never advances. With the sbt_wait on a wait list, kyber believes it has an active waiter so cannot insert a new waiter when reaching the domain's full state. This race can be fixed by only adding the sbt_wait to the queue if the sbq field is NULL. If sbq is not NULL, there is already an action active which will trigger the re-running of kyber. Let it run and add the sbt_wait to the wait list if still needing to wait. Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: David Jeffery <djeffery@redhat.com> Reported-by: John Pittman <jpittman@redhat.com> Tested-by: John Pittman <jpittman@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: Delete sbitmap_any_bit_clear()John Garry2019-11-131-17/+0
| | | | | | | | Since the only caller of this function has been deleted, delete this one also. Signed-off-by: John Garry <john.garry@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: Replace cmpxchg with xchgPavel Begunkov2019-07-011-7/+3
| | | | | | | | | | | | | | cmpxchg() with an immediate value could be replaced with less expensive xchg(). The same true if new value don't _depend_ on the old one. In the second block, atomic_cmpxchg() return value isn't checked, so after atomic_cmpxchg() -> atomic_xchg() conversion it could be replaced with atomic_set(). Comparison with atomic_read() in the second chunk was left as an optimisation (if that was the initial intention). Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 328Thomas Gleixner2019-06-051-12/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Based on 1 normalized pattern(s): this program is free software you can redistribute it and or modify it under the terms of the gnu general public license v2 as published by the free software foundation this program is distributed in the hope that it will be useful but without any warranty without even the implied warranty of merchantability or fitness for a particular purpose see the gnu general public license for more details you should have received a copy of the gnu general public license along with this program if not see https www gnu org licenses extracted by the scancode license scanner the SPDX license identifier GPL-2.0-only has been chosen to replace the boilerplate/reference in 2 file(s). Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Alexios Zavras <alexios.zavras@intel.com> Reviewed-by: Armijn Hemel <armijn@tjaldur.nl> Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Allison Randal <allison@lohutok.net> Cc: linux-spdx@vger.kernel.org Link: https://lkml.kernel.org/r/20190530000435.923873561@linutronix.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
* sbitmap: fix improper use of smp_mb__before_atomic()Andrea Parri2019-05-231-1/+1
| | | | | | | | | | | | | | | | | | | | | This barrier only applies to the read-modify-write operations; in particular, it does not apply to the atomic_set() primitive. Replace the barrier with an smp_mb(). Fixes: 6c0ca7ae292ad ("sbitmap: fix wakeup hang after sbq resize") Cc: stable@vger.kernel.org Reported-by: "Paul E. McKenney" <paulmck@linux.ibm.com> Reported-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Omar Sandoval <osandov@fb.com> Cc: Ming Lei <ming.lei@redhat.com> Cc: linux-block@vger.kernel.org Cc: "Paul E. McKenney" <paulmck@linux.ibm.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: order READ/WRITE freed instance and setting clear bitMing Lei2019-03-251-0/+11
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Inside sbitmap_queue_clear(), once the clear bit is set, it will be visiable to allocation path immediately. Meantime READ/WRITE on old associated instance(such as request in case of blk-mq) may be out-of-order with the setting clear bit, so race with re-allocation may be triggered. Adds one memory barrier for ordering READ/WRITE of the freed associated instance with setting clear bit for avoiding race with re-allocation. The following kernel oops triggerd by block/006 on aarch64 may be fixed: [ 142.330954] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000330 [ 142.338794] Mem abort info: [ 142.341554] ESR = 0x96000005 [ 142.344632] Exception class = DABT (current EL), IL = 32 bits [ 142.350500] SET = 0, FnV = 0 [ 142.353544] EA = 0, S1PTW = 0 [ 142.356678] Data abort info: [ 142.359528] ISV = 0, ISS = 0x00000005 [ 142.363343] CM = 0, WnR = 0 [ 142.366305] user pgtable: 64k pages, 48-bit VAs, pgdp = 000000002a3c51c0 [ 142.372983] [0000000000000330] pgd=0000000000000000, pud=0000000000000000 [ 142.379777] Internal error: Oops: 96000005 [#1] SMP [ 142.384613] Modules linked in: null_blk ib_isert iscsi_target_mod ib_srpt target_core_mod ib_srp scsi_transport_srp vfat fat rpcrdma sunrpc rdma_ucm ib_iser rdma_cm iw_cm libiscsi ib_umad scsi_transport_iscsi ib_ipoib ib_cm mlx5_ib ib_uverbs ib_core sbsa_gwdt crct10dif_ce ghash_ce ipmi_ssif sha2_ce ipmi_devintf sha256_arm64 sg sha1_ce ipmi_msghandler ip_tables xfs libcrc32c mlx5_core sdhci_acpi mlxfw ahci_platform at803x sdhci libahci_platform qcom_emac mmc_core hdma hdma_mgmt i2c_dev [last unloaded: null_blk] [ 142.429753] CPU: 7 PID: 1983 Comm: fio Not tainted 5.0.0.cki #2 [ 142.449458] pstate: 00400005 (nzcv daif +PAN -UAO) [ 142.454239] pc : __blk_mq_free_request+0x4c/0xa8 [ 142.458830] lr : blk_mq_free_request+0xec/0x118 [ 142.463344] sp : ffff00003360f6a0 [ 142.466646] x29: ffff00003360f6a0 x28: ffff000010e70000 [ 142.471941] x27: ffff801729a50048 x26: 0000000000010000 [ 142.477232] x25: ffff00003360f954 x24: ffff7bdfff021440 [ 142.482529] x23: 0000000000000000 x22: 00000000ffffffff [ 142.487830] x21: ffff801729810000 x20: 0000000000000000 [ 142.493123] x19: ffff801729a50000 x18: 0000000000000000 [ 142.498413] x17: 0000000000000000 x16: 0000000000000001 [ 142.503709] x15: 00000000000000ff x14: ffff7fe000000000 [ 142.509003] x13: ffff8017dcde09a0 x12: 0000000000000000 [ 142.514308] x11: 0000000000000001 x10: 0000000000000008 [ 142.519597] x9 : ffff8017dcde09a0 x8 : 0000000000002000 [ 142.524889] x7 : ffff8017dcde0a00 x6 : 000000015388f9be [ 142.530187] x5 : 0000000000000001 x4 : 0000000000000000 [ 142.535478] x3 : 0000000000000000 x2 : 0000000000000000 [ 142.540777] x1 : 0000000000000001 x0 : ffff00001041b194 [ 142.546071] Process fio (pid: 1983, stack limit = 0x000000006460a0ea) [ 142.552500] Call trace: [ 142.554926] __blk_mq_free_request+0x4c/0xa8 [ 142.559181] blk_mq_free_request+0xec/0x118 [ 142.563352] blk_mq_end_request+0xfc/0x120 [ 142.567444] end_cmd+0x3c/0xa8 [null_blk] [ 142.571434] null_complete_rq+0x20/0x30 [null_blk] [ 142.576194] blk_mq_complete_request+0x108/0x148 [ 142.580797] null_handle_cmd+0x1d4/0x718 [null_blk] [ 142.585662] null_queue_rq+0x60/0xa8 [null_blk] [ 142.590171] blk_mq_try_issue_directly+0x148/0x280 [ 142.594949] blk_mq_try_issue_list_directly+0x9c/0x108 [ 142.600064] blk_mq_sched_insert_requests+0xb0/0xd0 [ 142.604926] blk_mq_flush_plug_list+0x16c/0x2a0 [ 142.609441] blk_flush_plug_list+0xec/0x118 [ 142.613608] blk_finish_plug+0x3c/0x4c [ 142.617348] blkdev_direct_IO+0x3b4/0x428 [ 142.621336] generic_file_read_iter+0x84/0x180 [ 142.625761] blkdev_read_iter+0x50/0x78 [ 142.629579] aio_read.isra.6+0xf8/0x190 [ 142.633409] __io_submit_one.isra.8+0x148/0x738 [ 142.637912] io_submit_one.isra.9+0x88/0xb8 [ 142.642078] __arm64_sys_io_submit+0xe0/0x238 [ 142.646428] el0_svc_handler+0xa0/0x128 [ 142.650238] el0_svc+0x8/0xc [ 142.653104] Code: b9402a63 f9000a7f 3100047f 540000a0 (f9419a81) [ 142.659202] ---[ end trace 467586bc175eb09d ]--- Fixes: ea86ea2cdced20057da ("sbitmap: ammortize cost of clearing bits") Reported-and-bisected_and_tested-by: Yi Zhang <yi.zhang@redhat.com> Cc: Yi Zhang <yi.zhang@redhat.com> Cc: "jianchao.wang" <jianchao.w.wang@oracle.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: Protect swap_lock from hardirqMing Lei2019-01-151-2/+3
| | | | | | | | | | | | | | | | | | | Because we may call blk_mq_get_driver_tag() directly from blk_mq_dispatch_rq_list() without holding any lock, then HARDIRQ may come and the above DEADLOCK is triggered. Commit ab53dcfb3e7b ("sbitmap: Protect swap_lock from hardirq") tries to fix this issue by using 'spin_lock_bh', which isn't enough because we complete request from hardirq context direclty in case of multiqueue. Cc: Clark Williams <williams@redhat.com> Fixes: ab53dcfb3e7b ("sbitmap: Protect swap_lock from hardirq") Cc: Jens Axboe <axboe@kernel.dk> Cc: Ming Lei <ming.lei@redhat.com> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sbitmap: Protect swap_lock from softirqsSteven Rostedt (VMware)2019-01-151-10/+2
| | | | | | | | | | | | | | | | | | | | | | The swap_lock used by sbitmap has a chain with locks taken from softirq, but the swap_lock is not protected from being preempted by softirqs. A chain exists of: sbq->ws[i].wait -> dispatch_wait_lock -> swap_lock Where the sbq->ws[i].wait lock can be taken from softirq context, which means all locks below it in the chain must also be protected from softirqs. Reported-by: Clark Williams <williams@redhat.com> Fixes: 58ab5e32e6fd ("sbitmap: silence bogus lockdep IRQ warning") Fixes: ea86ea2cdced ("sbitmap: amortize cost of clearing bits") Cc: Jens Axboe <axboe@kernel.dk> Cc: Ming Lei <ming.lei@redhat.com> Cc: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* sbitmap: add helpers for add/del wait queue handlingJens Axboe2018-12-201-4/+26
| | | | | | | | | | | | | | After commit 5d2ee7122c73, users of sbitmap that need wait queue handling must use the provided helpers. But we only added prepare_to_wait()/finish_wait() style helpers, add the equivalent add_wait_queue/list_del wrappers as we.. This is needed to ensure kyber plays by the sbitmap waitqueue rules. Tested-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: flush deferred clears for resize and shallow getsJens Axboe2018-12-111-43/+51
| | | | | | | | | | | | | | We're missing a deferred clear off the shallow get, which can cause a hang. Additionally, when we resize the sbitmap, we should also flush deferred clears for good measure. Ensure we have full coverage on batch clears, even for paths where we would not be doing deferred clear. This makes it less error prone for future additions. Reported-by: Bart Van Assche <bvanassche@acm.org> Tested-by: Ming Lei <ming.lei@redhat.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: silence bogus lockdep IRQ warningJens Axboe2018-12-091-0/+8
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Ming reports that lockdep spews the following trace. What this essentially says is that the sbitmap swap_lock was used inconsistently in IRQ enabled and disabled context, and that is usually indicative of a bug that will cause a deadlock. For this case, it's a false positive. The swap_lock is used from process context only, when we swap the bits in the word and cleared mask. We also end up doing that when we are getting a driver tag, from the blk_mq_mark_tag_wait(), and from there we hold the waitqueue lock with IRQs disabled. However, this isn't from an actual IRQ, it's still process context. In lieu of a better way to fix this, simply always disable interrupts when grabbing the swap_lock if lockdep is enabled. [ 100.967642] ================start test sanity/001================ [ 101.238280] null: module loaded [ 106.093735] [ 106.094012] ===================================================== [ 106.094854] WARNING: SOFTIRQ-safe -> SOFTIRQ-unsafe lock order detected [ 106.095759] 4.20.0-rc3_5d2ee7122c73_for-next+ #1 Not tainted [ 106.096551] ----------------------------------------------------- [ 106.097386] fio/1043 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire: [ 106.098231] 000000004c43fa71 (&(&sb->map[i].swap_lock)->rlock){+.+.}, at: sbitmap_get+0xd5/0x22c [ 106.099431] [ 106.099431] and this task is already holding: [ 106.100229] 000000007eec8b2f (&(&hctx->dispatch_wait_lock)->rlock){....}, at: blk_mq_dispatch_rq_list+0x4c1/0xd7c [ 106.101630] which would create a new lock dependency: [ 106.102326] (&(&hctx->dispatch_wait_lock)->rlock){....} -> (&(&sb->map[i].swap_lock)->rlock){+.+.} [ 106.103553] [ 106.103553] but this new dependency connects a SOFTIRQ-irq-safe lock: [ 106.104580] (&sbq->ws[i].wait){..-.} [ 106.104582] [ 106.104582] ... which became SOFTIRQ-irq-safe at: [ 106.105751] _raw_spin_lock_irqsave+0x4b/0x82 [ 106.106284] __wake_up_common_lock+0x119/0x1b9 [ 106.106825] sbitmap_queue_wake_up+0x33f/0x383 [ 106.107456] sbitmap_queue_clear+0x4c/0x9a [ 106.108046] __blk_mq_free_request+0x188/0x1d3 [ 106.108581] blk_mq_free_request+0x23b/0x26b [ 106.109102] scsi_end_request+0x345/0x5d7 [ 106.109587] scsi_io_completion+0x4b5/0x8f0 [ 106.110099] scsi_finish_command+0x412/0x456 [ 106.110615] scsi_softirq_done+0x23f/0x29b [ 106.111115] blk_done_softirq+0x2a7/0x2e6 [ 106.111608] __do_softirq+0x360/0x6ad [ 106.112062] run_ksoftirqd+0x2f/0x5b [ 106.112499] smpboot_thread_fn+0x3a5/0x3db [ 106.113000] kthread+0x1d4/0x1e4 [ 106.113457] ret_from_fork+0x3a/0x50 [ 106.113969] [ 106.113969] to a SOFTIRQ-irq-unsafe lock: [ 106.114672] (&(&sb->map[i].swap_lock)->rlock){+.+.} [ 106.114674] [ 106.114674] ... which became SOFTIRQ-irq-unsafe at: [ 106.116000] ... [ 106.116003] _raw_spin_lock+0x33/0x64 [ 106.116676] sbitmap_get+0xd5/0x22c [ 106.117134] __sbitmap_queue_get+0xe8/0x177 [ 106.117731] __blk_mq_get_tag+0x1e6/0x22d [ 106.118286] blk_mq_get_tag+0x1db/0x6e4 [ 106.118756] blk_mq_get_driver_tag+0x161/0x258 [ 106.119383] blk_mq_dispatch_rq_list+0x28e/0xd7c [ 106.120043] blk_mq_do_dispatch_sched+0x23a/0x287 [ 106.120607] blk_mq_sched_dispatch_requests+0x379/0x3fc [ 106.121234] __blk_mq_run_hw_queue+0x137/0x17e [ 106.121781] __blk_mq_delay_run_hw_queue+0x80/0x25f [ 106.122366] blk_mq_run_hw_queue+0x151/0x187 [ 106.122887] blk_mq_sched_insert_requests+0x13f/0x175 [ 106.123492] blk_mq_flush_plug_list+0x7d6/0x81b [ 106.124042] blk_flush_plug_list+0x392/0x3d7 [ 106.124557] blk_finish_plug+0x37/0x4f [ 106.125019] read_pages+0x3ef/0x430 [ 106.125446] __do_page_cache_readahead+0x18e/0x2fc [ 106.126027] force_page_cache_readahead+0x121/0x133 [ 106.126621] page_cache_sync_readahead+0x35f/0x3bb [ 106.127229] generic_file_buffered_read+0x410/0x1860 [ 106.127932] __vfs_read+0x319/0x38f [ 106.128415] vfs_read+0xd2/0x19a [ 106.128817] ksys_read+0xb9/0x135 [ 106.129225] do_syscall_64+0x140/0x385 [ 106.129684] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 106.130292] [ 106.130292] other info that might help us debug this: [ 106.130292] [ 106.131226] Chain exists of: [ 106.131226] &sbq->ws[i].wait --> &(&hctx->dispatch_wait_lock)->rlock --> &(&sb->map[i].swap_lock)->rlock [ 106.131226] [ 106.132865] Possible interrupt unsafe locking scenario: [ 106.132865] [ 106.133659] CPU0 CPU1 [ 106.134194] ---- ---- [ 106.134733] lock(&(&sb->map[i].swap_lock)->rlock); [ 106.135318] local_irq_disable(); [ 106.136014] lock(&sbq->ws[i].wait); [ 106.136747] lock(&(&hctx->dispatch_wait_lock)->rlock); [ 106.137742] <Interrupt> [ 106.138110] lock(&sbq->ws[i].wait); [ 106.138625] [ 106.138625] *** DEADLOCK *** [ 106.138625] [ 106.139430] 3 locks held by fio/1043: [ 106.139947] #0: 0000000076ff0fd9 (rcu_read_lock){....}, at: hctx_lock+0x29/0xe8 [ 106.140813] #1: 000000002feb1016 (&sbq->ws[i].wait){..-.}, at: blk_mq_dispatch_rq_list+0x4ad/0xd7c [ 106.141877] #2: 000000007eec8b2f (&(&hctx->dispatch_wait_lock)->rlock){....}, at: blk_mq_dispatch_rq_list+0x4c1/0xd7c [ 106.143267] [ 106.143267] the dependencies between SOFTIRQ-irq-safe lock and the holding lock: [ 106.144351] -> (&sbq->ws[i].wait){..-.} ops: 82 { [ 106.144926] IN-SOFTIRQ-W at: [ 106.145314] _raw_spin_lock_irqsave+0x4b/0x82 [ 106.146042] __wake_up_common_lock+0x119/0x1b9 [ 106.146785] sbitmap_queue_wake_up+0x33f/0x383 [ 106.147567] sbitmap_queue_clear+0x4c/0x9a [ 106.148379] __blk_mq_free_request+0x188/0x1d3 [ 106.149148] blk_mq_free_request+0x23b/0x26b [ 106.149864] scsi_end_request+0x345/0x5d7 [ 106.150546] scsi_io_completion+0x4b5/0x8f0 [ 106.151367] scsi_finish_command+0x412/0x456 [ 106.152157] scsi_softirq_done+0x23f/0x29b [ 106.152855] blk_done_softirq+0x2a7/0x2e6 [ 106.153537] __do_softirq+0x360/0x6ad [ 106.154280] run_ksoftirqd+0x2f/0x5b [ 106.155020] smpboot_thread_fn+0x3a5/0x3db [ 106.155828] kthread+0x1d4/0x1e4 [ 106.156526] ret_from_fork+0x3a/0x50 [ 106.157267] INITIAL USE at: [ 106.157713] _raw_spin_lock_irqsave+0x4b/0x82 [ 106.158542] prepare_to_wait_exclusive+0xa8/0x215 [ 106.159421] blk_mq_get_tag+0x34f/0x6e4 [ 106.160186] blk_mq_get_request+0x48e/0xaef [ 106.160997] blk_mq_make_request+0x27e/0xbd2 [ 106.161828] generic_make_request+0x4d1/0x873 [ 106.162661] submit_bio+0x20c/0x253 [ 106.163379] mpage_bio_submit+0x44/0x4b [ 106.164142] mpage_readpages+0x3c2/0x407 [ 106.164919] read_pages+0x13a/0x430 [ 106.165633] __do_page_cache_readahead+0x18e/0x2fc [ 106.166530] force_page_cache_readahead+0x121/0x133 [ 106.167439] page_cache_sync_readahead+0x35f/0x3bb [ 106.168337] generic_file_buffered_read+0x410/0x1860 [ 106.169255] __vfs_read+0x319/0x38f [ 106.169977] vfs_read+0xd2/0x19a [ 106.170662] ksys_read+0xb9/0x135 [ 106.171356] do_syscall_64+0x140/0x385 [ 106.172120] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 106.173051] } [ 106.173308] ... key at: [<ffffffff85094600>] __key.26481+0x0/0x40 [ 106.174219] ... acquired at: [ 106.174646] _raw_spin_lock+0x33/0x64 [ 106.175183] blk_mq_dispatch_rq_list+0x4c1/0xd7c [ 106.175843] blk_mq_do_dispatch_sched+0x23a/0x287 [ 106.176518] blk_mq_sched_dispatch_requests+0x379/0x3fc [ 106.177262] __blk_mq_run_hw_queue+0x137/0x17e [ 106.177900] __blk_mq_delay_run_hw_queue+0x80/0x25f [ 106.178591] blk_mq_run_hw_queue+0x151/0x187 [ 106.179207] blk_mq_sched_insert_requests+0x13f/0x175 [ 106.179926] blk_mq_flush_plug_list+0x7d6/0x81b [ 106.180571] blk_flush_plug_list+0x392/0x3d7 [ 106.181187] blk_finish_plug+0x37/0x4f [ 106.181737] __se_sys_io_submit+0x171/0x304 [ 106.182346] do_syscall_64+0x140/0x385 [ 106.182895] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 106.183607] [ 106.183830] -> (&(&hctx->dispatch_wait_lock)->rlock){....} ops: 1 { [ 106.184691] INITIAL USE at: [ 106.185119] _raw_spin_lock+0x33/0x64 [ 106.185838] blk_mq_dispatch_rq_list+0x4c1/0xd7c [ 106.186697] blk_mq_do_dispatch_sched+0x23a/0x287 [ 106.187551] blk_mq_sched_dispatch_requests+0x379/0x3fc [ 106.188481] __blk_mq_run_hw_queue+0x137/0x17e [ 106.189307] __blk_mq_delay_run_hw_queue+0x80/0x25f [ 106.190189] blk_mq_run_hw_queue+0x151/0x187 [ 106.190989] blk_mq_sched_insert_requests+0x13f/0x175 [ 106.191902] blk_mq_flush_plug_list+0x7d6/0x81b [ 106.192739] blk_flush_plug_list+0x392/0x3d7 [ 106.193535] blk_finish_plug+0x37/0x4f [ 106.194269] __se_sys_io_submit+0x171/0x304 [ 106.195059] do_syscall_64+0x140/0x385 [ 106.195794] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 106.196705] } [ 106.196950] ... key at: [<ffffffff84880620>] __key.51231+0x0/0x40 [ 106.197853] ... acquired at: [ 106.198270] lock_acquire+0x280/0x2f3 [ 106.198806] _raw_spin_lock+0x33/0x64 [ 106.199337] sbitmap_get+0xd5/0x22c [ 106.199850] __sbitmap_queue_get+0xe8/0x177 [ 106.200450] __blk_mq_get_tag+0x1e6/0x22d [ 106.201035] blk_mq_get_tag+0x1db/0x6e4 [ 106.201589] blk_mq_get_driver_tag+0x161/0x258 [ 106.202237] blk_mq_dispatch_rq_list+0x5b9/0xd7c [ 106.202902] blk_mq_do_dispatch_sched+0x23a/0x287 [ 106.203572] blk_mq_sched_dispatch_requests+0x379/0x3fc [ 106.204316] __blk_mq_run_hw_queue+0x137/0x17e [ 106.204956] __blk_mq_delay_run_hw_queue+0x80/0x25f [ 106.205649] blk_mq_run_hw_queue+0x151/0x187 [ 106.206269] blk_mq_sched_insert_requests+0x13f/0x175 [ 106.206997] blk_mq_flush_plug_list+0x7d6/0x81b [ 106.207644] blk_flush_plug_list+0x392/0x3d7 [ 106.208264] blk_finish_plug+0x37/0x4f [ 106.208814] __se_sys_io_submit+0x171/0x304 [ 106.209415] do_syscall_64+0x140/0x385 [ 106.209965] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 106.210684] [ 106.210904] [ 106.210904] the dependencies between the lock to be acquired [ 106.210905] and SOFTIRQ-irq-unsafe lock: [ 106.212541] -> (&(&sb->map[i].swap_lock)->rlock){+.+.} ops: 1969 { [ 106.213393] HARDIRQ-ON-W at: [ 106.213840] _raw_spin_lock+0x33/0x64 [ 106.214570] sbitmap_get+0xd5/0x22c [ 106.215282] __sbitmap_queue_get+0xe8/0x177 [ 106.216086] __blk_mq_get_tag+0x1e6/0x22d [ 106.216876] blk_mq_get_tag+0x1db/0x6e4 [ 106.217627] blk_mq_get_driver_tag+0x161/0x258 [ 106.218465] blk_mq_dispatch_rq_list+0x28e/0xd7c [ 106.219326] blk_mq_do_dispatch_sched+0x23a/0x287 [ 106.220198] blk_mq_sched_dispatch_requests+0x379/0x3fc [ 106.221138] __blk_mq_run_hw_queue+0x137/0x17e [ 106.221975] __blk_mq_delay_run_hw_queue+0x80/0x25f [ 106.222874] blk_mq_run_hw_queue+0x151/0x187 [ 106.223686] blk_mq_sched_insert_requests+0x13f/0x175 [ 106.224597] blk_mq_flush_plug_list+0x7d6/0x81b [ 106.225444] blk_flush_plug_list+0x392/0x3d7 [ 106.226255] blk_finish_plug+0x37/0x4f [ 106.227006] read_pages+0x3ef/0x430 [ 106.227717] __do_page_cache_readahead+0x18e/0x2fc [ 106.228595] force_page_cache_readahead+0x121/0x133 [ 106.229491] page_cache_sync_readahead+0x35f/0x3bb [ 106.230373] generic_file_buffered_read+0x410/0x1860 [ 106.231277] __vfs_read+0x319/0x38f [ 106.231986] vfs_read+0xd2/0x19a [ 106.232666] ksys_read+0xb9/0x135 [ 106.233350] do_syscall_64+0x140/0x385 [ 106.234097] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 106.235012] SOFTIRQ-ON-W at: [ 106.235460] _raw_spin_lock+0x33/0x64 [ 106.236195] sbitmap_get+0xd5/0x22c [ 106.236913] __sbitmap_queue_get+0xe8/0x177 [ 106.237715] __blk_mq_get_tag+0x1e6/0x22d [ 106.238488] blk_mq_get_tag+0x1db/0x6e4 [ 106.239244] blk_mq_get_driver_tag+0x161/0x258 [ 106.240079] blk_mq_dispatch_rq_list+0x28e/0xd7c [ 106.240937] blk_mq_do_dispatch_sched+0x23a/0x287 [ 106.241806] blk_mq_sched_dispatch_requests+0x379/0x3fc [ 106.242751] __blk_mq_run_hw_queue+0x137/0x17e [ 106.243579] __blk_mq_delay_run_hw_queue+0x80/0x25f [ 106.244469] blk_mq_run_hw_queue+0x151/0x187 [ 106.245277] blk_mq_sched_insert_requests+0x13f/0x175 [ 106.246191] blk_mq_flush_plug_list+0x7d6/0x81b [ 106.247044] blk_flush_plug_list+0x392/0x3d7 [ 106.247859] blk_finish_plug+0x37/0x4f [ 106.248749] read_pages+0x3ef/0x430 [ 106.249463] __do_page_cache_readahead+0x18e/0x2fc [ 106.250357] force_page_cache_readahead+0x121/0x133 [ 106.251263] page_cache_sync_readahead+0x35f/0x3bb [ 106.252157] generic_file_buffered_read+0x410/0x1860 [ 106.253084] __vfs_read+0x319/0x38f [ 106.253808] vfs_read+0xd2/0x19a [ 106.254488] ksys_read+0xb9/0x135 [ 106.255186] do_syscall_64+0x140/0x385 [ 106.255943] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 106.256867] INITIAL USE at: [ 106.257300] _raw_spin_lock+0x33/0x64 [ 106.258033] sbitmap_get+0xd5/0x22c [ 106.258747] __sbitmap_queue_get+0xe8/0x177 [ 106.259542] __blk_mq_get_tag+0x1e6/0x22d [ 106.260320] blk_mq_get_tag+0x1db/0x6e4 [ 106.261072] blk_mq_get_driver_tag+0x161/0x258 [ 106.261902] blk_mq_dispatch_rq_list+0x28e/0xd7c [ 106.262762] blk_mq_do_dispatch_sched+0x23a/0x287 [ 106.263626] blk_mq_sched_dispatch_requests+0x379/0x3fc [ 106.264571] __blk_mq_run_hw_queue+0x137/0x17e [ 106.265409] __blk_mq_delay_run_hw_queue+0x80/0x25f [ 106.266302] blk_mq_run_hw_queue+0x151/0x187 [ 106.267111] blk_mq_sched_insert_requests+0x13f/0x175 [ 106.268028] blk_mq_flush_plug_list+0x7d6/0x81b [ 106.268878] blk_flush_plug_list+0x392/0x3d7 [ 106.269694] blk_finish_plug+0x37/0x4f [ 106.270432] read_pages+0x3ef/0x430 [ 106.271139] __do_page_cache_readahead+0x18e/0x2fc [ 106.272040] force_page_cache_readahead+0x121/0x133 [ 106.272932] page_cache_sync_readahead+0x35f/0x3bb [ 106.273811] generic_file_buffered_read+0x410/0x1860 [ 106.274709] __vfs_read+0x319/0x38f [ 106.275407] vfs_read+0xd2/0x19a [ 106.276074] ksys_read+0xb9/0x135 [ 106.276764] do_syscall_64+0x140/0x385 [ 106.277500] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 106.278417] } [ 106.278676] ... key at: [<ffffffff85094640>] __key.26212+0x0/0x40 [ 106.279586] ... acquired at: [ 106.280026] lock_acquire+0x280/0x2f3 [ 106.280559] _raw_spin_lock+0x33/0x64 [ 106.281101] sbitmap_get+0xd5/0x22c [ 106.281610] __sbitmap_queue_get+0xe8/0x177 [ 106.282221] __blk_mq_get_tag+0x1e6/0x22d [ 106.282809] blk_mq_get_tag+0x1db/0x6e4 [ 106.283368] blk_mq_get_driver_tag+0x161/0x258 [ 106.284018] blk_mq_dispatch_rq_list+0x5b9/0xd7c [ 106.284685] blk_mq_do_dispatch_sched+0x23a/0x287 [ 106.285371] blk_mq_sched_dispatch_requests+0x379/0x3fc [ 106.286135] __blk_mq_run_hw_queue+0x137/0x17e [ 106.286806] __blk_mq_delay_run_hw_queue+0x80/0x25f [ 106.287515] blk_mq_run_hw_queue+0x151/0x187 [ 106.288149] blk_mq_sched_insert_requests+0x13f/0x175 [ 106.289041] blk_mq_flush_plug_list+0x7d6/0x81b [ 106.289912] blk_flush_plug_list+0x392/0x3d7 [ 106.290590] blk_finish_plug+0x37/0x4f [ 106.291238] __se_sys_io_submit+0x171/0x304 [ 106.291864] do_syscall_64+0x140/0x385 [ 106.292534] entry_SYSCALL_64_after_hwframe+0x49/0xbe Reported-by: Ming Lei <ming.lei@redhat.com> Tested-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: optimize wakeup checkJens Axboe2018-11-301-0/+28
| | | | | | | | | | | | | | | | | Even if we have no waiters on any of the sbitmap_queue wait states, we still have to loop every entry to check. We do this for every IO, so the cost adds up. Shift a bit of the cost to the slow path, when we actually have waiters. Wrap prepare_to_wait_exclusive() and finish_wait(), so we can maintain an internal count of how many are currently active. Then we can simply check this count in sbq_wake_ptr() and not have to loop if we don't have any sleepers. Convert the two users of sbitmap with waiting, blk-mq-tag and iSCSI. Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: ammortize cost of clearing bitsJens Axboe2018-11-301-8/+73
| | | | | | | | | | | | | | | | | | | | sbitmap maintains a set of words that we use to set and clear bits, with each bit representing a tag for blk-mq. Even though we spread the bits out and maintain a hint cache, one particular bit allocated will end up being cleared in the exact same spot. This introduces batched clearing of bits. Instead of clearing a given bit, the same bit is set in a cleared/free mask instead. If we fail allocating a bit from a given word, then we check the free mask, and batch move those cleared bits at that time. This trades 64 atomic bitops for 2 cmpxchg(). In a threaded poll test case, half the overhead of getting and clearing tags is removed with this change. On another poll test case with a single thread, performance is unchanged. Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: don't loop for find_next_zero_bit() for !round_robinJens Axboe2018-11-291-8/+13
| | | | | | | | | | | If we aren't forced to do round robin tag allocation, just use the allocation hint to find the index for the tag word, don't use it for the offset inside the word. This avoids a potential extra round trip in the bit looping, and since we're fetching this cacheline, we may as well check the whole word from the start. Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* treewide: kzalloc_node() -> kcalloc_node()Kees Cook2018-06-121-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The kzalloc_node() function has a 2-factor argument form, kcalloc_node(). This patch replaces cases of: kzalloc_node(a * b, gfp, node) with: kcalloc_node(a * b, gfp, node) as well as handling cases of: kzalloc_node(a * b * c, gfp, node) with: kzalloc_node(array3_size(a, b, c), gfp, node) as it's slightly less ugly than: kcalloc_node(array_size(a, b), c, gfp, node) This does, however, attempt to ignore constant size factors like: kzalloc_node(4 * 1024, gfp, node) though any constants defined via macros get caught up in the conversion. Any factors with a sizeof() of "unsigned char", "char", and "u8" were dropped, since they're redundant. The Coccinelle script used for this was: // Fix redundant parens around sizeof(). @@ type TYPE; expression THING, E; @@ ( kzalloc_node( - (sizeof(TYPE)) * E + sizeof(TYPE) * E , ...) | kzalloc_node( - (sizeof(THING)) * E + sizeof(THING) * E , ...) ) // Drop single-byte sizes and redundant parens. @@ expression COUNT; typedef u8; typedef __u8; @@ ( kzalloc_node( - sizeof(u8) * (COUNT) + COUNT , ...) | kzalloc_node( - sizeof(__u8) * (COUNT) + COUNT , ...) | kzalloc_node( - sizeof(char) * (COUNT) + COUNT , ...) | kzalloc_node( - sizeof(unsigned char) * (COUNT) + COUNT , ...) | kzalloc_node( - sizeof(u8) * COUNT + COUNT , ...) | kzalloc_node( - sizeof(__u8) * COUNT + COUNT , ...) | kzalloc_node( - sizeof(char) * COUNT + COUNT , ...) | kzalloc_node( - sizeof(unsigned char) * COUNT + COUNT , ...) ) // 2-factor product with sizeof(type/expression) and identifier or constant. @@ type TYPE; expression THING; identifier COUNT_ID; constant COUNT_CONST; @@ ( - kzalloc_node + kcalloc_node ( - sizeof(TYPE) * (COUNT_ID) + COUNT_ID, sizeof(TYPE) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(TYPE) * COUNT_ID + COUNT_ID, sizeof(TYPE) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(TYPE) * (COUNT_CONST) + COUNT_CONST, sizeof(TYPE) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(TYPE) * COUNT_CONST + COUNT_CONST, sizeof(TYPE) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(THING) * (COUNT_ID) + COUNT_ID, sizeof(THING) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(THING) * COUNT_ID + COUNT_ID, sizeof(THING) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(THING) * (COUNT_CONST) + COUNT_CONST, sizeof(THING) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(THING) * COUNT_CONST + COUNT_CONST, sizeof(THING) , ...) ) // 2-factor product, only identifiers. @@ identifier SIZE, COUNT; @@ - kzalloc_node + kcalloc_node ( - SIZE * COUNT + COUNT, SIZE , ...) // 3-factor product with 1 sizeof(type) or sizeof(expression), with // redundant parens removed. @@ expression THING; identifier STRIDE, COUNT; type TYPE; @@ ( kzalloc_node( - sizeof(TYPE) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kzalloc_node( - sizeof(TYPE) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kzalloc_node( - sizeof(TYPE) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kzalloc_node( - sizeof(TYPE) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(TYPE)) , ...) | kzalloc_node( - sizeof(THING) * (COUNT) * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kzalloc_node( - sizeof(THING) * (COUNT) * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kzalloc_node( - sizeof(THING) * COUNT * (STRIDE) + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) | kzalloc_node( - sizeof(THING) * COUNT * STRIDE + array3_size(COUNT, STRIDE, sizeof(THING)) , ...) ) // 3-factor product with 2 sizeof(variable), with redundant parens removed. @@ expression THING1, THING2; identifier COUNT; type TYPE1, TYPE2; @@ ( kzalloc_node( - sizeof(TYPE1) * sizeof(TYPE2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kzalloc_node( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(TYPE2)) , ...) | kzalloc_node( - sizeof(THING1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kzalloc_node( - sizeof(THING1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(THING1), sizeof(THING2)) , ...) | kzalloc_node( - sizeof(TYPE1) * sizeof(THING2) * COUNT + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) | kzalloc_node( - sizeof(TYPE1) * sizeof(THING2) * (COUNT) + array3_size(COUNT, sizeof(TYPE1), sizeof(THING2)) , ...) ) // 3-factor product, only identifiers, with redundant parens removed. @@ identifier STRIDE, SIZE, COUNT; @@ ( kzalloc_node( - (COUNT) * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc_node( - COUNT * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc_node( - COUNT * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc_node( - (COUNT) * (STRIDE) * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc_node( - COUNT * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc_node( - (COUNT) * STRIDE * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc_node( - (COUNT) * (STRIDE) * (SIZE) + array3_size(COUNT, STRIDE, SIZE) , ...) | kzalloc_node( - COUNT * STRIDE * SIZE + array3_size(COUNT, STRIDE, SIZE) , ...) ) // Any remaining multi-factor products, first at least 3-factor products, // when they're not all constants... @@ expression E1, E2, E3; constant C1, C2, C3; @@ ( kzalloc_node(C1 * C2 * C3, ...) | kzalloc_node( - (E1) * E2 * E3 + array3_size(E1, E2, E3) , ...) | kzalloc_node( - (E1) * (E2) * E3 + array3_size(E1, E2, E3) , ...) | kzalloc_node( - (E1) * (E2) * (E3) + array3_size(E1, E2, E3) , ...) | kzalloc_node( - E1 * E2 * E3 + array3_size(E1, E2, E3) , ...) ) // And then all remaining 2 factors products when they're not all constants, // keeping sizeof() as the second factor argument. @@ expression THING, E1, E2; type TYPE; constant C1, C2, C3; @@ ( kzalloc_node(sizeof(THING) * C2, ...) | kzalloc_node(sizeof(TYPE) * C2, ...) | kzalloc_node(C1 * C2 * C3, ...) | kzalloc_node(C1 * C2, ...) | - kzalloc_node + kcalloc_node ( - sizeof(TYPE) * (E2) + E2, sizeof(TYPE) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(TYPE) * E2 + E2, sizeof(TYPE) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(THING) * (E2) + E2, sizeof(THING) , ...) | - kzalloc_node + kcalloc_node ( - sizeof(THING) * E2 + E2, sizeof(THING) , ...) | - kzalloc_node + kcalloc_node ( - (E1) * E2 + E1, E2 , ...) | - kzalloc_node + kcalloc_node ( - (E1) * (E2) + E1, E2 , ...) | - kzalloc_node + kcalloc_node ( - E1 * E2 + E1, E2 , ...) ) Signed-off-by: Kees Cook <keescook@chromium.org>
* blk-mq: avoid starving tag allocation after allocating process migratesMing Lei2018-05-241-14/+15
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | When the allocation process is scheduled back and the mapped hw queue is changed, fake one extra wake up on previous queue for compensating wake up miss, so other allocations on the previous queue won't be starved. This patch fixes one request allocation hang issue, which can be triggered easily in case of very low nr_request. The race is as follows: 1) 2 hw queues, nr_requests are 2, and wake_batch is one 2) there are 3 waiters on hw queue 0 3) two in-flight requests in hw queue 0 are completed, and only two waiters of 3 are waken up because of wake_batch, but both the two waiters can be scheduled to another CPU and cause to switch to hw queue 1 4) then the 3rd waiter will wait for ever, since no in-flight request is in hw queue 0 any more. 5) this patch fixes it by the fake wakeup when waiter is scheduled to another hw queue Cc: <stable@vger.kernel.org> Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Ming Lei <ming.lei@redhat.com> Modified commit message to make it clearer, and make it apply on top of the 4.18 branch. Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: fix race in wait batch accountingJens Axboe2018-05-141-10/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If we have multiple callers of sbq_wake_up(), we can end up in a situation where the wait_cnt will continually go more and more negative. Consider the case where our wake batch is 1, hence wait_cnt will start out as 1. wait_cnt == 1 CPU0 CPU1 atomic_dec_return(), cnt == 0 atomic_dec_return(), cnt == -1 cmpxchg(-1, 0) (succeeds) [wait_cnt now 0] cmpxchg(0, 1) (fails) This ends up with wait_cnt being 0, we'll wakeup immediately next time. Going through the same loop as above again, and we'll have wait_cnt -1. For the case where we have a larger wake batch, the only difference is that the starting point will be higher. We'll still end up with continually smaller batch wakeups, which defeats the purpose of the rolling wakeups. Always reset the wait_cnt to the batch value. Then it doesn't matter who wins the race. But ensure that whomever does win the race is the one that increments the ws index and wakes up our batch count, loser gets to call __sbq_wake_up() again to account his wakeups towards the next active wait state index. Fixes: 6c0ca7ae292a ("sbitmap: fix wakeup hang after sbq resize") Reviewed-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: warn if using smaller shallow depth than was setupOmar Sandoval2018-05-101-0/+2
| | | | | | | | | Make sure the user passed the right value to sbitmap_queue_min_shallow_depth(). Acked-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: fix missed wakeups caused by sbitmap_queue_get_shallow()Omar Sandoval2018-05-101-9/+40
| | | | | | | | | | | | | | | The sbitmap queue wake batch is calculated such that once allocations start blocking, all of the bits which are already allocated must be enough to fulfill the batch counters of all of the waitqueues. However, the shallow allocation depth can break this invariant, since we block before our full depth is being utilized. Add sbitmap_queue_min_shallow_depth(), which saves the minimum shallow depth the sbq will use, and update sbq_calc_wake_batch() to take it into account. Acked-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* sbitmap: use test_and_set_bit_lock()/clear_bit_unlock()Omar Sandoval2018-02-281-5/+5
| | | | | | | | | | | | | | | | | | | sbitmap_queue_get()/sbitmap_queue_clear() are used for allocating/freeing a resource, so they should provide acquire/release barrier semantics, respectively. sbitmap_get() currently contains a full barrier, which is unnecessary, so use test_and_set_bit_lock() instead of test_and_set_bit() (these are equivalent on x86_64). sbitmap_clear_bit() does not imply any barriers, which is incorrect, as accesses of the resource (e.g., request) could potentially get reordered to after the clear_bit(). Introduce sbitmap_clear_bit_unlock() and use it for sbitmap_queue_clear() (this only adds a compiler barrier on x86_64). The other existing user of sbitmap_clear_bit() (the blk-mq software queue pending map) is serialized through a spinlock and does not need this. Reported-by: Tejun Heo <tj@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
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