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* blk-mq: add shallow depth option for blk_mq_get_tag()Omar Sandoval2017-04-141-1/+4
| | | | | | | | Wire up the sbitmap_get_shallow() operation to the tag code so that a caller can limit the number of tags available to it. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: Fix tagset reinit in the presence of cpu hot-unplugSagi Grimberg2017-03-131-0/+3
| | | | | | | | | | In case cpu was unplugged, we need to make sure not to assume that the tags for that cpu are still allocated. so check for null tags when reinitializing a tagset. Reported-by: Yi Zhang <yizhan@redhat.com> Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq-sched: Allocate sched reserved tags as specified in the original ↵Sagi Grimberg2017-03-021-1/+1
| | | | | | | | | | | | queue tagset Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Modified by me to also check at driver tag allocation time if the original request was reserved, so we can be sure to allocate a properly reserved tag at that point in time, too. Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq-sched: add flush insertion into blk_mq_sched_insert_request()Jens Axboe2017-01-271-1/+7
| | | | | | | | | | Instead of letting the caller check this and handle the details of inserting a flush request, put the logic in the scheduler insertion function. This fixes direct flush insertion outside of the usual make_request_fn calls, like from dm via blk_insert_cloned_request(). Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: move tags and sched_tags info from sysfs to debugfsOmar Sandoval2017-01-271-27/+0
| | | | | | | | | | | These are very tied to the blk-mq tag implementation, so exposing them to sysfs isn't a great idea. Move the debugging information to debugfs and add basic entries for the number of tags and the number of reserved tags to sysfs. Reviewed-by: Hannes Reinecke <hare@suse.com> Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: only apply active queue tag throttling for driver tagsJens Axboe2017-01-251-5/+7
| | | | | | | | | If we have a scheduler attached, we have two sets of tags. We don't want to apply our active queue throttling for the scheduler side of tags, that only applies to driver tags since that's the resource we need to dispatch an IO. Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: allow resize of scheduler requestsJens Axboe2017-01-201-7/+44
| | | | | | | | | | | | | Add support for growing the tags associated with a hardware queue, for the scheduler tags. Currently we only support resizing within the limits of the original depth, change that so we can grow it as well by allocating and replacing the existing scheduler tag set. This is similar to how we could increase the software queue depth with the legacy IO stack and schedulers. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Omar Sandoval <osandov@fb.com>
* blk-mq-tag: remove redundant check for 'data->hctx' being non-NULLJens Axboe2017-01-191-4/+2
| | | | | | | | | | We used to pass in NULL for hctx for reserved tags, but we don't do that anymore. Hence the check for whether hctx is NULL or not is now redundant, kill it. Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Fixes: a642a158aec6 ("blk-mq-tag: cleanup the normal/reserved tag allocation") Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: split tag ->rqs[] into twoJens Axboe2017-01-171-2/+2
| | | | | | | | This is in preparation for having two sets of tags available. For that we need a static index, and a dynamically assignable one. Signed-off-by: Jens Axboe <axboe@fb.com> Reviewed-by: Omar Sandoval <osandov@fb.com>
* blk-mq-tag: cleanup the normal/reserved tag allocationJens Axboe2017-01-171-58/+36
| | | | | | | | | | This is in preparation for having another tag set available. Cleanup the parameters, and allow passing in of tags for blk_mq_put_tag(). Signed-off-by: Jens Axboe <axboe@fb.com> [hch: even more cleanups] Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Omar Sandoval <osandov@fb.com>
* Merge branch 'for-4.9/block-irq' of git://git.kernel.dk/linux-blockLinus Torvalds2016-10-091-9/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull blk-mq irq/cpu mapping updates from Jens Axboe: "This is the block-irq topic branch for 4.9-rc. It's mostly from Christoph, and it allows drivers to specify their own mappings, and more importantly, to share the blk-mq mappings with the IRQ affinity mappings. It's a good step towards making this work better out of the box" * 'for-4.9/block-irq' of git://git.kernel.dk/linux-block: blk_mq: linux/blk-mq.h does not include all the headers it depends on blk-mq: kill unused blk_mq_create_mq_map() blk-mq: get rid of the cpumask in struct blk_mq_tags nvme: remove the post_scan callout nvme: switch to use pci_alloc_irq_vectors blk-mq: provide a default queue mapping for PCI device blk-mq: allow the driver to pass in a queue mapping blk-mq: remove ->map_queue blk-mq: only allocate a single mq_map per tag_set blk-mq: don't redistribute hardware queues on a CPU hotplug event
| * blk-mq: get rid of the cpumask in struct blk_mq_tagsChristoph Hellwig2016-09-151-6/+0
| | | | | | | | | | | | | | | | Unused now that NVMe sets up irq affinity before calling into blk-mq. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: remove ->map_queueChristoph Hellwig2016-09-151-3/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | All drivers use the default, so provide an inline version of it. If we ever need other queue mapping we can add an optional method back, although supporting will also require major changes to the queue setup code. This provides better code generation, and better debugability as well. Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* | sbitmap: randomize initial alloc_hint valuesOmar Sandoval2016-09-171-8/+0
| | | | | | | | | | | | | | | | | | | | | | | | In order to get good cache behavior from a sbitmap, we want each CPU to stick to its own cacheline(s) as much as possible. This might happen naturally as the bitmap gets filled up and the alloc_hint values spread out, but we really want this behavior from the start. blk-mq apparently intended to do this, but the code to do this was never wired up. Get rid of the dead code and make it part of the sbitmap library. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* | sbitmap: push alloc policy into sbitmap_queueOmar Sandoval2016-09-171-18/+15
| | | | | | | | | | | | | | | | Again, there's no point in passing this in every time. Make it part of struct sbitmap_queue and clean up the API. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* | sbitmap: push per-cpu last_tag into sbitmap_queueOmar Sandoval2016-09-171-36/+17
| | | | | | | | | | | | | | | | | | | | Allocating your own per-cpu allocation hint separately makes for an awkward API. Instead, allocate the per-cpu hint as part of the struct sbitmap_queue. There's no point for a struct sbitmap_queue without the cache, but you can still use a bare struct sbitmap. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* | blk-mq: abstract tag allocation out into sbitmap libraryOmar Sandoval2016-09-171-353/+110
|/ | | | | | | | | | | | | | This is a generally useful data structure, so make it available to anyone else who might want to use it. It's also a nice cleanup separating the allocation logic from the rest of the tag handling logic. The code is behind a new Kconfig option, CONFIG_SBITMAP, which is only selected by CONFIG_BLOCK for now. This should be a complete noop functionality-wise. Signed-off-by: Omar Sandoval <osandov@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: Introduce blk_mq_reinit_tagsetSagi Grimberg2016-07-081-0/+26
| | | | | | | | | | | | | | | The new nvme-rdma driver will need to reinitialize all the tags as part of the error recovery procedure (realloc the tag memory region). Add a helper in blk-mq for it that can iterate over all requests in a tagset to make this easier. Signed-off-by: Sagi Grimberg <sagi@grimberg.me> Tested-by: Ming Lin <ming.l@ssi.samsung.com> Reviewed-by: Stephen Bates <Stephen.Bates@pmcs.com> Signed-off-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Steve Wise <swise@opengridcomputing.com> Tested-by: Steve Wise <swise@opengridcomputing.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: Make blk_mq_all_tag_busy_iter staticSagi Grimberg2016-04-121-3/+2
| | | | | | | | | | No caller outside the blk-mq code so we can settle with it static. Signed-off-by: Sagi Grimberg <sagig@mellanox.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: Export tagset iter functionSagi Grimberg2016-04-121-0/+12
| | | | | | | | | | | Its useful to iterate on all the active tags in cases where we will need to fail all the queues IO. Signed-off-by: Sagi Grimberg <sagig@mellanox.com> [hch: carefully check for valid tagsets] Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: add a flags parameter to blk_mq_alloc_requestChristoph Hellwig2015-12-011-6/+5
| | | | | | | | | We already have the reserved flag, and a nowait flag awkwardly encoded as a gfp_t. Add a real flags argument to make the scheme more extensible and allow for a nicer calling convention. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
* mm, page_alloc: distinguish between being unable to sleep, unwilling to ↵Mel Gorman2015-11-061-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | sleep and avoiding waking kswapd __GFP_WAIT has been used to identify atomic context in callers that hold spinlocks or are in interrupts. They are expected to be high priority and have access one of two watermarks lower than "min" which can be referred to as the "atomic reserve". __GFP_HIGH users get access to the first lower watermark and can be called the "high priority reserve". Over time, callers had a requirement to not block when fallback options were available. Some have abused __GFP_WAIT leading to a situation where an optimisitic allocation with a fallback option can access atomic reserves. This patch uses __GFP_ATOMIC to identify callers that are truely atomic, cannot sleep and have no alternative. High priority users continue to use __GFP_HIGH. __GFP_DIRECT_RECLAIM identifies callers that can sleep and are willing to enter direct reclaim. __GFP_KSWAPD_RECLAIM to identify callers that want to wake kswapd for background reclaim. __GFP_WAIT is redefined as a caller that is willing to enter direct reclaim and wake kswapd for background reclaim. This patch then converts a number of sites o __GFP_ATOMIC is used by callers that are high priority and have memory pools for those requests. GFP_ATOMIC uses this flag. o Callers that have a limited mempool to guarantee forward progress clear __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall into this category where kswapd will still be woken but atomic reserves are not used as there is a one-entry mempool to guarantee progress. o Callers that are checking if they are non-blocking should use the helper gfpflags_allow_blocking() where possible. This is because checking for __GFP_WAIT as was done historically now can trigger false positives. Some exceptions like dm-crypt.c exist where the code intent is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to flag manipulations. o Callers that built their own GFP flags instead of starting with GFP_KERNEL and friends now also need to specify __GFP_KSWAPD_RECLAIM. The first key hazard to watch out for is callers that removed __GFP_WAIT and was depending on access to atomic reserves for inconspicuous reasons. In some cases it may be appropriate for them to use __GFP_HIGH. The second key hazard is callers that assembled their own combination of GFP flags instead of starting with something like GFP_KERNEL. They may now wish to specify __GFP_KSWAPD_RECLAIM. It's almost certainly harmless if it's missed in most cases as other activity will wake kswapd. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Christoph Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Vitaly Wool <vitalywool@gmail.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* Merge branch 'for-4.4/core' of git://git.kernel.dk/linux-blockLinus Torvalds2015-11-041-0/+4
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull core block updates from Jens Axboe: "This is the core block pull request for 4.4. I've got a few more topic branches this time around, some of them will layer on top of the core+drivers changes and will come in a separate round. So not a huge chunk of changes in this round. This pull request contains: - Enable blk-mq page allocation tracking with kmemleak, from Catalin. - Unused prototype removal in blk-mq from Christoph. - Cleanup of the q->blk_trace exchange, using cmpxchg instead of two xchg()'s, from Davidlohr. - A plug flush fix from Jeff. - Also from Jeff, a fix that means we don't have to update shared tag sets at init time unless we do a state change. This cuts down boot times on thousands of devices a lot with scsi/blk-mq. - blk-mq waitqueue barrier fix from Kosuke. - Various fixes from Ming: - Fixes for segment merging and splitting, and checks, for the old core and blk-mq. - Potential blk-mq speedup by marking ctx pending at the end of a plug insertion batch in blk-mq. - direct-io no page dirty on kernel direct reads. - A WRITE_SYNC fix for mpage from Roman" * 'for-4.4/core' of git://git.kernel.dk/linux-block: blk-mq: avoid excessive boot delays with large lun counts blktrace: re-write setting q->blk_trace blk-mq: mark ctx as pending at batch in flush plug path blk-mq: fix for trace_block_plug() block: check bio_mergeable() early before merging blk-mq: check bio_mergeable() early before merging block: avoid to merge splitted bio block: setup bi_phys_segments after splitting block: fix plug list flushing for nomerge queues blk-mq: remove unused blk_mq_clone_flush_request prototype blk-mq: fix waitqueue_active without memory barrier in block/blk-mq-tag.c fs: direct-io: don't dirtying pages for ITER_BVEC/ITER_KVEC direct read fs/mpage.c: forgotten WRITE_SYNC in case of data integrity write block: kmemleak: Track the page allocations for struct request
| * blk-mq: fix waitqueue_active without memory barrier in block/blk-mq-tag.cKosuke Tatsukawa2015-10-091-0/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | blk_mq_tag_update_depth() seems to be missing a memory barrier which might cause the waker to not notice the waiter and fail to send a wake_up as in the following figure. blk_mq_tag_update_depth bt_get ------------------------------------------------------------------------ if (waitqueue_active(&bs->wait)) /* The CPU might reorder the test for the waitqueue up here, before prior writes complete */ prepare_to_wait(&bs->wait, &wait, TASK_UNINTERRUPTIBLE); tag = __bt_get(hctx, bt, last_tag, tags); /* Value set in bt_update_count not visible yet */ bt_update_count(&tags->bitmap_tags, tdepth); /* blk_mq_tag_wakeup_all(tags, false); */ bt = &tags->bitmap_tags; wake_index = atomic_read(&bt->wake_index); ... io_schedule(); ------------------------------------------------------------------------ This patch adds the missing memory barrier. I found this issue when I was looking through the linux source code for places calling waitqueue_active() before wake_up*(), but without preceding memory barriers, after sending a patch to fix a similar issue in drivers/tty/n_tty.c (Details about the original issue can be found here: https://lkml.org/lkml/2015/9/28/849). Signed-off-by: Kosuke Tatsukawa <tatsu@ab.jp.nec.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* | blk-mq: fix use-after-free in blk_mq_free_tag_set()Junichi Nomura2015-10-151-0/+1
|/ | | | | | | | | | | | | | | tags is freed in blk_mq_free_rq_map() and should not be used after that. The problem doesn't manifest if CONFIG_CPUMASK_OFFSTACK is false because free_cpumask_var() is nop. tags->cpumask is allocated in blk_mq_init_tags() so it's natural to free cpumask in its counter part, blk_mq_free_tags(). Fixes: f26cdc8536ad ("blk-mq: Shared tag enhancements") Signed-off-by: Jun'ichi Nomura <j-nomura@ce.jp.nec.com> Cc: Keith Busch <keith.busch@intel.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: factor out a helper to iterate all tags for a request_queueChristoph Hellwig2015-10-011-7/+20
| | | | | | | | | And replace the blk_mq_tag_busy_iter with it - the driver use has been replaced with a new helper a while ago, and internal to the block we only need the new version. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: fix race between timeout and freeing requestMing Lei2015-08-151-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Inside timeout handler, blk_mq_tag_to_rq() is called to retrieve the request from one tag. This way is obviously wrong because the request can be freed any time and some fiedds of the request can't be trusted, then kernel oops might be triggered[1]. Currently wrt. blk_mq_tag_to_rq(), the only special case is that the flush request can share same tag with the request cloned from, and the two requests can't be active at the same time, so this patch fixes the above issue by updating tags->rqs[tag] with the active request(either flush rq or the request cloned from) of the tag. Also blk_mq_tag_to_rq() gets much simplified with this patch. Given blk_mq_tag_to_rq() is mainly for drivers and the caller must make sure the request can't be freed, so in bt_for_each() this helper is replaced with tags->rqs[tag]. [1] kernel oops log [ 439.696220] BUG: unable to handle kernel NULL pointer dereference at 0000000000000158^M [ 439.697162] IP: [<ffffffff812d89ba>] blk_mq_tag_to_rq+0x21/0x6e^M [ 439.700653] PGD 7ef765067 PUD 7ef764067 PMD 0 ^M [ 439.700653] Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC ^M [ 439.700653] Dumping ftrace buffer:^M [ 439.700653] (ftrace buffer empty)^M [ 439.700653] Modules linked in: nbd ipv6 kvm_intel kvm serio_raw^M [ 439.700653] CPU: 6 PID: 2779 Comm: stress-ng-sigfd Not tainted 4.2.0-rc5-next-20150805+ #265^M [ 439.730500] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011^M [ 439.730500] task: ffff880605308000 ti: ffff88060530c000 task.ti: ffff88060530c000^M [ 439.730500] RIP: 0010:[<ffffffff812d89ba>] [<ffffffff812d89ba>] blk_mq_tag_to_rq+0x21/0x6e^M [ 439.730500] RSP: 0018:ffff880819203da0 EFLAGS: 00010283^M [ 439.730500] RAX: ffff880811b0e000 RBX: ffff8800bb465f00 RCX: 0000000000000002^M [ 439.730500] RDX: 0000000000000000 RSI: 0000000000000202 RDI: 0000000000000000^M [ 439.730500] RBP: ffff880819203db0 R08: 0000000000000002 R09: 0000000000000000^M [ 439.730500] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000202^M [ 439.730500] R13: ffff880814104800 R14: 0000000000000002 R15: ffff880811a2ea00^M [ 439.730500] FS: 00007f165b3f5740(0000) GS:ffff880819200000(0000) knlGS:0000000000000000^M [ 439.730500] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b^M [ 439.730500] CR2: 0000000000000158 CR3: 00000007ef766000 CR4: 00000000000006e0^M [ 439.730500] Stack:^M [ 439.730500] 0000000000000008 ffff8808114eed90 ffff880819203e00 ffffffff812dc104^M [ 439.755663] ffff880819203e40 ffffffff812d9f5e 0000020000000000 ffff8808114eed80^M [ 439.755663] Call Trace:^M [ 439.755663] <IRQ> ^M [ 439.755663] [<ffffffff812dc104>] bt_for_each+0x6e/0xc8^M [ 439.755663] [<ffffffff812d9f5e>] ? blk_mq_rq_timed_out+0x6a/0x6a^M [ 439.755663] [<ffffffff812d9f5e>] ? blk_mq_rq_timed_out+0x6a/0x6a^M [ 439.755663] [<ffffffff812dc1b3>] blk_mq_tag_busy_iter+0x55/0x5e^M [ 439.755663] [<ffffffff812d88b4>] ? blk_mq_bio_to_request+0x38/0x38^M [ 439.755663] [<ffffffff812d8911>] blk_mq_rq_timer+0x5d/0xd4^M [ 439.755663] [<ffffffff810a3e10>] call_timer_fn+0xf7/0x284^M [ 439.755663] [<ffffffff810a3d1e>] ? call_timer_fn+0x5/0x284^M [ 439.755663] [<ffffffff812d88b4>] ? blk_mq_bio_to_request+0x38/0x38^M [ 439.755663] [<ffffffff810a46d6>] run_timer_softirq+0x1ce/0x1f8^M [ 439.755663] [<ffffffff8104c367>] __do_softirq+0x181/0x3a4^M [ 439.755663] [<ffffffff8104c76e>] irq_exit+0x40/0x94^M [ 439.755663] [<ffffffff81031482>] smp_apic_timer_interrupt+0x33/0x3e^M [ 439.755663] [<ffffffff815559a4>] apic_timer_interrupt+0x84/0x90^M [ 439.755663] <EOI> ^M [ 439.755663] [<ffffffff81554350>] ? _raw_spin_unlock_irq+0x32/0x4a^M [ 439.755663] [<ffffffff8106a98b>] finish_task_switch+0xe0/0x163^M [ 439.755663] [<ffffffff8106a94d>] ? finish_task_switch+0xa2/0x163^M [ 439.755663] [<ffffffff81550066>] __schedule+0x469/0x6cd^M [ 439.755663] [<ffffffff8155039b>] schedule+0x82/0x9a^M [ 439.789267] [<ffffffff8119b28b>] signalfd_read+0x186/0x49a^M [ 439.790911] [<ffffffff8106d86a>] ? wake_up_q+0x47/0x47^M [ 439.790911] [<ffffffff811618c2>] __vfs_read+0x28/0x9f^M [ 439.790911] [<ffffffff8117a289>] ? __fget_light+0x4d/0x74^M [ 439.790911] [<ffffffff811620a7>] vfs_read+0x7a/0xc6^M [ 439.790911] [<ffffffff8116292b>] SyS_read+0x49/0x7f^M [ 439.790911] [<ffffffff81554c17>] entry_SYSCALL_64_fastpath+0x12/0x6f^M [ 439.790911] Code: 48 89 e5 e8 a9 b8 e7 ff 5d c3 0f 1f 44 00 00 55 89 f2 48 89 e5 41 54 41 89 f4 53 48 8b 47 60 48 8b 1c d0 48 8b 7b 30 48 8b 53 38 <48> 8b 87 58 01 00 00 48 85 c0 75 09 48 8b 97 88 0c 00 00 eb 10 ^M [ 439.790911] RIP [<ffffffff812d89ba>] blk_mq_tag_to_rq+0x21/0x6e^M [ 439.790911] RSP <ffff880819203da0>^M [ 439.790911] CR2: 0000000000000158^M [ 439.790911] ---[ end trace d40af58949325661 ]---^M Cc: <stable@vger.kernel.org> Signed-off-by: Ming Lei <ming.lei@canonical.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: Shared tag enhancementsKeith Busch2015-06-011-0/+38
| | | | | | | | | | | | Storage controllers may expose multiple block devices that share hardware resources managed by blk-mq. This patch enhances the shared tags so a low-level driver can access the shared resources not tied to the unshared h/w contexts. This way the LLD can dynamically add and delete disks and request queues without having to track all the request_queue hctx's to iterate outstanding tags. Signed-off-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blkmq: Fix NULL pointer deref when all reserved tags inSam Bradshaw2015-03-181-2/+4
| | | | | | | | | | | | | | | | | | | When allocating from the reserved tags pool, bt_get() is called with a NULL hctx. If all tags are in use, the hw queue is kicked to push out any pending IO, potentially freeing tags, and tag allocation is retried. The problem is that blk_mq_run_hw_queue() doesn't check for a NULL hctx. So we avoid it with a simple NULL hctx test. Tested by hammering mtip32xx with concurrent smartctl/hdparm. Signed-off-by: Sam Bradshaw <sbradshaw@micron.com> Signed-off-by: Selvan Mani <smani@micron.com> Fixes: b32232073e80 ("blk-mq: fix hang in bt_get()") Cc: stable@kernel.org Added appropriate comment. Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: fix double-free in error pathTony Battersby2015-02-111-0/+1
| | | | | | | | | | | If the allocation of bt->bs fails, then bt->map can be freed twice, once in blk_mq_init_bitmap_tags() -> bt_alloc(), and once in blk_mq_init_bitmap_tags() -> bt_free(). Fix by setting the pointer to NULL after the first free. Cc: <stable@vger.kernel.org> Signed-off-by: Tony Battersby <tonyb@cybernetics.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: add tag allocation policyShaohua Li2015-01-231-15/+24
| | | | | | | | | | | | | | | This is the blk-mq part to support tag allocation policy. The default allocation policy isn't changed (though it's not a strict FIFO). The new policy is round-robin for libata. But it's a try-best implementation. If multiple tasks are competing, the tags returned will be mixed (which is unavoidable even with !mq, as requests from different tasks can be mixed in queue) Cc: Jens Axboe <axboe@fb.com> Cc: Tejun Heo <tj@kernel.org> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Shaohua Li <shli@fb.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: fix false negative out-of-tags conditionJens Axboe2015-01-141-17/+26
| | | | | | | | | | | | | | | | | | | The blk-mq tagging tries to maintain some locality between CPUs and the tags issued. The tags are split into groups of words, and the words may not be fully populated. When searching for a new free tag, blk-mq may look at partial words, hence it passes in an offset/size to find_next_zero_bit(). However, it does that wrong, the size must always be the full length of the number of tags in that word, otherwise we'll potentially miss some near the end. Another issue is when __bt_get() goes from one word set to the next. It bumps the index, but not the last_tag associated with the previous index. Bump that to be in the range of the new word. Finally, clean up __bt_get() and __bt_get_word() a bit and get rid of the goto in there, and the unnecessary 'wrap' variable. Signed-off-by: Jens Axboe <axboe@fb.com>
* block: wake up waiters when a queue is marked dyingJens Axboe2014-12-311-4/+10
| | | | | | | | | | | If it's dying, we can't expect new request to complete and come in an wake up other tasks waiting for requests. So after we have marked it as dying, wake up everybody currently waiting for a request. Once they wake, they will retry their allocation and fail appropriately due to the state of the queue. Tested-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* Revert "blk-mq: Micro-optimize bt_get()"Jens Axboe2014-12-151-1/+3
| | | | | | | | | | | This reverts commit 52f7eb945f2ba62b324bb9ae16d945326a961dcf. The optimization is only really safe for a single queue, otherwise 'bs' and 'bt' can indeed change, and if we don't do a finish_wait() for each loop, we'll potentially change the wait structure and corrupt task wait list. Reported-by: Jan Kara <jack@suse.cz>
* Merge branch 'for-3.19/core' of git://git.kernel.dk/linux-blockLinus Torvalds2014-12-131-29/+31
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull block driver core update from Jens Axboe: "This is the pull request for the core block IO changes for 3.19. Not a huge round this time, mostly lots of little good fixes: - Fix a bug in sysfs blktrace interface causing a NULL pointer dereference, when enabled/disabled through that API. From Arianna Avanzini. - Various updates/fixes/improvements for blk-mq: - A set of updates from Bart, mostly fixing buts in the tag handling. - Cleanup/code consolidation from Christoph. - Extend queue_rq API to be able to handle batching issues of IO requests. NVMe will utilize this shortly. From me. - A few tag and request handling updates from me. - Cleanup of the preempt handling for running queues from Paolo. - Prevent running of unmapped hardware queues from Ming Lei. - Move the kdump memory limiting check to be in the correct location, from Shaohua. - Initialize all software queues at init time from Takashi. This prevents a kobject warning when CPUs are brought online that weren't online when a queue was registered. - Single writeback fix for I_DIRTY clearing from Tejun. Queued with the core IO changes, since it's just a single fix. - Version X of the __bio_add_page() segment addition retry from Maurizio. Hope the Xth time is the charm. - Documentation fixup for IO scheduler merging from Jan. - Introduce (and use) generic IO stat accounting helpers for non-rq drivers, from Gu Zheng. - Kill off artificial limiting of max sectors in a request from Christoph" * 'for-3.19/core' of git://git.kernel.dk/linux-block: (26 commits) bio: modify __bio_add_page() to accept pages that don't start a new segment blk-mq: Fix uninitialized kobject at CPU hotplugging blktrace: don't let the sysfs interface remove trace from running list blk-mq: Use all available hardware queues blk-mq: Micro-optimize bt_get() blk-mq: Fix a race between bt_clear_tag() and bt_get() blk-mq: Avoid that __bt_get_word() wraps multiple times blk-mq: Fix a use-after-free blk-mq: prevent unmapped hw queue from being scheduled blk-mq: re-check for available tags after running the hardware queue blk-mq: fix hang in bt_get() blk-mq: move the kdump check to blk_mq_alloc_tag_set blk-mq: cleanup tag free handling blk-mq: use 'nr_cpu_ids' as highest CPU ID count for hwq <-> cpu map blk: introduce generic io stat accounting help function blk-mq: handle the single queue case in blk_mq_hctx_next_cpu genhd: check for int overflow in disk_expand_part_tbl() blk-mq: add blk_mq_free_hctx_request() blk-mq: export blk_mq_free_request() blk-mq: use get_cpu/put_cpu instead of preempt_disable/preempt_enable ...
| * blk-mq: Micro-optimize bt_get()Bart Van Assche2014-12-091-3/+1
| | | | | | | | | | | | | | | | | | | | | | | | Remove a superfluous finish_wait() call. Convert the two bt_wait_ptr() calls into a single call. Signed-off-by: Bart Van Assche <bvanassche@acm.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Robert Elliott <elliott@hp.com> Cc: Ming Lei <ming.lei@canonical.com> Cc: Alexander Gordeev <agordeev@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: Fix a race between bt_clear_tag() and bt_get()Bart Van Assche2014-12-091-6/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | What we need is the following two guarantees: * Any thread that observes the effect of the test_and_set_bit() by __bt_get_word() also observes the preceding addition of 'current' to the appropriate wait list. This is guaranteed by the semantics of the spin_unlock() operation performed by prepare_and_wait(). Hence the conversion of test_and_set_bit_lock() into test_and_set_bit(). * The wait lists are examined by bt_clear() after the tag bit has been cleared. clear_bit_unlock() guarantees that any thread that observes that the bit has been cleared also observes the store operations preceding clear_bit_unlock(). However, clear_bit_unlock() does not prevent that the wait lists are examined before that the tag bit is cleared. Hence the addition of a memory barrier between clear_bit() and the wait list examination. Signed-off-by: Bart Van Assche <bvanassche@acm.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Robert Elliott <elliott@hp.com> Cc: Ming Lei <ming.lei@canonical.com> Cc: Alexander Gordeev <agordeev@redhat.com> Cc: <stable@vger.kernel.org> # v3.13+ Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: Avoid that __bt_get_word() wraps multiple timesBart Van Assche2014-12-091-2/+4
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | If __bt_get_word() is called with last_tag != 0, if the first find_next_zero_bit() fails, if after wrap-around the test_and_set_bit() call fails and find_next_zero_bit() succeeds, if the next test_and_set_bit() call fails and subsequently find_next_zero_bit() does not find a zero bit, then another wrap-around will occur. Avoid this by introducing an additional local variable. Signed-off-by: Bart Van Assche <bvanassche@acm.org> Cc: Christoph Hellwig <hch@lst.de> Cc: Robert Elliott <elliott@hp.com> Cc: Ming Lei <ming.lei@canonical.com> Cc: Alexander Gordeev <agordeev@redhat.com> Cc: <stable@vger.kernel.org> # v3.13+ Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: re-check for available tags after running the hardware queueJens Axboe2014-12-081-0/+8
| | | | | | | | | | | | | | | | If we run out of tags and have to sleep, we run the hardware queue to kick pending IO into gear. During that run, we may have completed requests, so re-check if we have free tags before going to sleep. Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: fix hang in bt_get()Bart Van Assche2014-12-081-0/+7
| | | | | | | | | | | | | | | | | | | | | | | | Avoid that if there are fewer hardware queues than CPU threads that bt_get() can hang. The symptoms of the hang were as follows: * All tags allocated for a particular hardware queue. * (nr_tags) pending commands for that hardware queue. * No pending commands for the software queues associated with that hardware queue. Signed-off-by: Jens Axboe <axboe@fb.com>
| * blk-mq: cleanup tag free handlingJens Axboe2014-11-241-18/+6
| | | | | | | | | | | | | | | | We only call __blk_mq_put_tag() and __blk_mq_put_reserved_tag() from blk_mq_put_tag(), so just inline the two calls instead of having them as separate functions. Signed-off-by: Jens Axboe <axboe@fb.com>
* | blk-mq: add blk_mq_unique_tag()Bart Van Assche2014-11-121-0/+28
|/ | | | | | | | | | | | | | | | The queuecommand() callback functions in SCSI low-level drivers need to know which hardware context has been selected by the block layer. Since this information is not available in the request structure, and since passing the hctx pointer directly to the queuecommand callback function would require modification of all SCSI LLDs, add a function to the block layer that allows to query the hardware context index. Signed-off-by: Bart Van Assche <bvanassche@acm.org> Acked-by: Jens Axboe <axboe@kernel.dk> Reviewed-by: Sagi Grimberg <sagig@mellanox.com> Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> Signed-off-by: Christoph Hellwig <hch@lst.de>
* blk-mq: Make bt_clear_tag() easier to readBart Van Assche2014-10-071-5/+2
| | | | | | | Eliminate a backwards goto statement from bt_clear_tag(). Signed-off-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: fix potential hang if rolling wakeup depth is too highJens Axboe2014-10-071-2/+2
| | | | | | | | | | | | | | We currently divide the queue depth by 4 as our batch wakeup count, but we split the wakeups over BT_WAIT_QUEUES number of wait queues. This defaults to 8. If the product of the resulting batch wake count and BT_WAIT_QUEUES is higher than the device queue depth, we can get into a situation where a task goes to sleep waiting for a request, but never gets woken up. Reported-by: Bart Van Assche <bvanassche@acm.org> Fixes: 4bb659b156996 Cc: stable@kernel.org Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: fix and simplify tag iteration for the timeout handlerChristoph Hellwig2014-09-221-26/+18
| | | | | | | | | | | | Don't do a kmalloc from timer to handle timeouts, chances are we could be under heavy load or similar and thus just miss out on the timeouts. Fortunately it is very easy to just iterate over all in use tags, and doing this properly actually cleans up the blk_mq_busy_iter API as well, and prepares us for the next patch by passing a reserved argument to the iterator. Signed-off-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: bitmap tag: fix races in bt_get() functionAlexander Gordeev2014-06-171-8/+5
| | | | | | | | | | | | | | | | | | | This update fixes few issues in bt_get() function: - list_empty(&wait.task_list) check is not protected; - was_empty check is always true which results in *every* thread entering the loop resets bt_wait_state::wait_cnt counter rather than every bt->wake_cnt'th thread; - 'bt_wait_state::wait_cnt' counter update is redundant, since it also gets reset in bt_clear_tag() function; Cc: Christoph Hellwig <hch@infradead.org> Cc: Ming Lei <tom.leiming@gmail.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Alexander Gordeev <agordeev@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: bitmap tag: fix race on blk_mq_bitmap_tags::wake_cntAlexander Gordeev2014-06-171-2/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This piece of code in bt_clear_tag() function is racy: bs = bt_wake_ptr(bt); if (bs && atomic_dec_and_test(&bs->wait_cnt)) { atomic_set(&bs->wait_cnt, bt->wake_cnt); wake_up(&bs->wait); } Since nothing prevents bt_wake_ptr() from returning the very same 'bs' address on multiple CPUs, the following scenario is possible: CPU1 CPU2 ---- ---- 0. bs = bt_wake_ptr(bt); bs = bt_wake_ptr(bt); 1. atomic_dec_and_test(&bs->wait_cnt) 2. atomic_dec_and_test(&bs->wait_cnt) 3. atomic_set(&bs->wait_cnt, bt->wake_cnt); If the decrement in [1] yields zero then for some amount of time the decrement in [2] results in a negative/overflow value, which is not expected. The follow-up assignment in [3] overwrites the invalid value with the batch value (and likely prevents the issue from being severe) which is still incorrect and should be a lesser. Cc: Ming Lei <tom.leiming@gmail.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Alexander Gordeev <agordeev@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: bitmap tag: fix races on shared ::wake_index fieldsAlexander Gordeev2014-06-171-11/+21
| | | | | | | | | Fix racy updates of shared blk_mq_bitmap_tags::wake_index and blk_mq_hw_ctx::wake_index fields. Cc: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Alexander Gordeev <agordeev@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: fix schedule from atomic contextMing Lei2014-06-031-17/+31
| | | | | | | | | | | blk_mq_put_ctx() has to be called before io_schedule() in bt_get(). This patch fixes the problem by taking similar approach from percpu_ida allocation for the situation. Signed-off-by: Ming Lei <tom.leiming@gmail.com> Signed-off-by: Jens Axboe <axboe@fb.com>
* blk-mq: add file comments and update copyright noticesJens Axboe2014-05-281-0/+12
| | | | | | | | None of the blk-mq files have an explanatory comment at the top for what that particular file does. Add that and add appropriate copyright notices as well. Signed-off-by: Jens Axboe <axboe@fb.com>
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