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This patch avoids that sparse reports the following:
block/blk-mq.c:637:33: warning: context imbalance in 'hctx_unlock' - unexpected unlock
block/blk-mq.c:642:9: warning: context imbalance in 'hctx_lock' - wrong count at exit
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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After the first few months, the message has not led to many bug reports.
It's been almost five years now, and in practice the main source of
it seems to be MTIOCGET that someone is using to detect tape devices.
While we could whitelist it just like CDROM_GET_CAPABILITY, this patch
just removes the message altogether.
The patch also removes the "safe but not very useful" ioctl whitelist,
as suggested by Christoph. I doubt anything is using most of those
ioctls _in general_, let alone on a partition.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Move completion related items (like the call single data) near the
end of the struct, instead of mixing them in with the initial
queueing related fields.
Move queuelist below the bio structures. Then we have all
queueing related bits in the first cache line.
This yields a 1.5-2% increase in IOPS for a null_blk test, both for
sync and for high thread count access. Sync test goes form 975K to
992K, 32-thread case from 20.8M to 21.2M IOPS.
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We only have one atomic flag left. Instead of using an entire
unsigned long for that, steal the bottom bit of the deadline
field that we already reserved.
Remove ->atomic_flags, since it's now unused.
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We reduce the resolution of request expiry, but since we're already
using jiffies for this where resolution depends on the kernel
configuration and since the timeout resolution is coarse anyway,
that should be fine.
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We don't need this to be an atomic flag, it can be a regular
flag. We either end up on the same CPU for the polling, in which
case the state is sane, or we did the sleep which would imply
the needed barrier to ensure we see the right state.
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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We are missing ZONE_WRITE_LOCKED and MQ_TIMEOUT_EXPIRED, add them
so the debugfs bits can decode them.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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It is nontrivial to derive from the blk-mq source code when
blk_mq_tags.active_queues is decremented. Hence add a comment that
explains this.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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UFS partitions from newer versions of FreeBSD 10 and 11 use relative
addressing for their subpartitions. But older versions of FreeBSD still
use absolute addressing just like OpenBSD and NetBSD.
Instead of simply testing for a FreeBSD partition, the code needs to
also test if the starting offset of the C subpartition is zero.
https://bugzilla.kernel.org/show_bug.cgi?id=197733
Signed-off-by: Richard Narron <comet.berkeley@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Commit '7b9e93616399' ("blk-mq-sched: unify request finished methods")
changed the old name of current bfq_finish_request method, but left it
unchanged elsewhere in the code (related comments, part of function
name bfq_put_rq_priv_body).
This commit fixes all occurrences of the old name of this method by
changing them into the current name.
Fixes: 7b9e93616399 ("blk-mq-sched: unify request finished methods")
Reviewed-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Federico Motta <federico@willer.it>
Signed-off-by: Chiara Bruschi <bruschi.chiara@outlook.it>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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This reverts commit a2d37968d784363842f87820a21e106741d28004.
If max segment size isn't 512-aligned, this patch won't work well.
Also once multipage bvec is enabled, adjacent bvecs won't be physically
contiguous if page is added via bio_add_page(), so we don't need this
kind of complicated logic.
Reported-by: Dmitry Osipenko <digetx@gmail.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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It's not available if we don't have group io scheduling set, and
there's no need to call it.
Fixes: 0d52af590552 ("block, bfq: release oom-queue ref to root group on exit")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Commit 3a025e1d1c2e ("Add optional check for bad kernel-doc comments")
causes W=1 the kernel-doc script to be run and thereby causes several
new warnings to appear when building the kernel with W=1. Fix the
block layer kernel-doc headers such that the block layer again builds
cleanly with W=1.
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Change "nedeing" into "needing" and "caes" into "cases".
Fixes: commit f906a6a0f426 ("blk-mq: improve tag waiting setup for non-shared tags")
Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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In some stupider versions of gcc, it complains:
block/blk-mq.c: In function ‘blk_mq_complete_request’:
./include/linux/srcu.h:175:2: warning: ‘srcu_idx’ may be used uninitialized in this function [-Wmaybe-uninitialized]
__srcu_read_unlock(sp, idx);
^
block/blk-mq.c:620:6: note: ‘srcu_idx’ was declared here
int srcu_idx;
^
which is completely bogus, since we only use srcu_idx when
hctx->flags & BLK_MQ_F_BLOCKING is set, and that's the case where
hctx_lock() has initialized it.
Just set it to '0' in the normal path in hctx_lock() to silence
this annoying warning.
Fixes: 04ced159cec8 ("blk-mq: move hctx lock/unlock into a helper")
Fixes: 5197c05e16b4 ("blk-mq: protect completion path with RCU")
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The RCU protection has been expanded to cover both queueing and
completion paths making ->queue_rq_srcu a misnomer. Rename it to
->srcu as suggested by Bart.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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After the recent updates to use generation number and state based
synchronization, we can easily replace REQ_ATOM_STARTED usages by
adding an extra state to distinguish completed but not yet freed
state.
Add MQ_RQ_COMPLETE and replace REQ_ATOM_STARTED usages with
blk_mq_rq_state() tests. REQ_ATOM_STARTED no longer has any users
left and is removed.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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After the recent updates to use generation number and state based
synchronization, blk-mq no longer depends on REQ_ATOM_COMPLETE except
to avoid firing the same timeout multiple times.
Remove all REQ_ATOM_COMPLETE usages and use a new rq_flags flag
RQF_MQ_TIMEOUT_EXPIRED to avoid firing the same timeout multiple
times. This removes atomic bitops from hot paths too.
v2: Removed blk_clear_rq_complete() from blk_mq_rq_timed_out().
v3: Added RQF_MQ_TIMEOUT_EXPIRED flag.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: "jianchao.wang" <jianchao.w.wang@oracle.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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With issue/complete and timeout paths now using the generation number
and state based synchronization, blk_abort_request() is the only one
which depends on REQ_ATOM_COMPLETE for arbitrating completion.
There's no reason for blk_abort_request() to be a completely separate
path. This patch makes blk_abort_request() piggyback on the timeout
path instead of trying to terminate the request directly.
This removes the last dependency on REQ_ATOM_COMPLETE in blk-mq.
Note that this makes blk_abort_request() asynchronous - it initiates
abortion but the actual termination will happen after a short while,
even when the caller owns the request. AFAICS, SCSI and ATA should be
fine with that and I think mtip32xx and dasd should be safe but not
completely sure. It'd be great if people who know the drivers take a
look.
v2: - Add comment explaining the lack of synchronization around
->deadline update as requested by Bart.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Asai Thambi SP <asamymuthupa@micron.com>
Cc: Stefan Haberland <sth@linux.vnet.ibm.com>
Cc: Jan Hoeppner <hoeppner@linux.vnet.ibm.com>
Cc: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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blk_mq_check_inflight() and blk_mq_poll_hybrid_sleep() test
REQ_ATOM_COMPLETE to determine the request state. Both uses are
speculative and we can test REQ_ATOM_STARTED and blk_mq_rq_state() for
equivalent results. Replace the tests. This will allow removing
REQ_ATOM_COMPLETE usages from blk-mq.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Currently, blk-mq timeout path synchronizes against the usual
issue/completion path using a complex scheme involving atomic
bitflags, REQ_ATOM_*, memory barriers and subtle memory coherence
rules. Unfortunately, it contains quite a few holes.
There's a complex dancing around REQ_ATOM_STARTED and
REQ_ATOM_COMPLETE between issue/completion and timeout paths; however,
they don't have a synchronization point across request recycle
instances and it isn't clear what the barriers add.
blk_mq_check_expired() can easily read STARTED from N-2'th iteration,
deadline from N-1'th, blk_mark_rq_complete() against Nth instance.
In fact, it's pretty easy to make blk_mq_check_expired() terminate a
later instance of a request. If we induce 5 sec delay before
time_after_eq() test in blk_mq_check_expired(), shorten the timeout to
2s, and issue back-to-back large IOs, blk-mq starts timing out
requests spuriously pretty quickly. Nothing actually timed out. It
just made the call on a recycle instance of a request and then
terminated a later instance long after the original instance finished.
The scenario isn't theoretical either.
This patch replaces the broken synchronization mechanism with a RCU
and generation number based one.
1. Each request has a u64 generation + state value, which can be
updated only by the request owner. Whenever a request becomes
in-flight, the generation number gets bumped up too. This provides
the basis for the timeout path to distinguish different recycle
instances of the request.
Also, marking a request in-flight and setting its deadline are
protected with a seqcount so that the timeout path can fetch both
values coherently.
2. The timeout path fetches the generation, state and deadline. If
the verdict is timeout, it records the generation into a dedicated
request abortion field and does RCU wait.
3. The completion path is also protected by RCU (from the previous
patch) and checks whether the current generation number and state
match the abortion field. If so, it skips completion.
4. The timeout path, after RCU wait, scans requests again and
terminates the ones whose generation and state still match the ones
requested for abortion.
By now, the timeout path knows that either the generation number
and state changed if it lost the race or the completion will yield
to it and can safely timeout the request.
While it's more lines of code, it's conceptually simpler, doesn't
depend on direct use of subtle memory ordering or coherence, and
hopefully doesn't terminate the wrong instance.
While this change makes REQ_ATOM_COMPLETE synchronization unnecessary
between issue/complete and timeout paths, REQ_ATOM_COMPLETE isn't
removed yet as it's still used in other places. Future patches will
move all state tracking to the new mechanism and remove all bitops in
the hot paths.
Note that this patch adds a comment explaining a race condition in
BLK_EH_RESET_TIMER path. The race has always been there and this
patch doesn't change it. It's just documenting the existing race.
v2: - Fixed BLK_EH_RESET_TIMER handling as pointed out by Jianchao.
- s/request->gstate_seqc/request->gstate_seq/ as suggested by Peter.
- READ_ONCE() added in blk_mq_rq_update_state() as suggested by Peter.
v3: - Fixed possible extended seqcount / u64_stats_sync read looping
spotted by Peter.
- MQ_RQ_IDLE was incorrectly being set in complete_request instead
of free_request. Fixed.
v4: - Rebased on top of hctx_lock() refactoring patch.
- Added comment explaining the use of hctx_lock() in completion path.
v5: - Added comments requested by Bart.
- Note the addition of BLK_EH_RESET_TIMER race condition in the
commit message.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: "jianchao.wang" <jianchao.w.wang@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Bart Van Assche <Bart.VanAssche@wdc.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Currently, blk-mq protects only the issue path with RCU. This patch
puts the completion path under the same RCU protection. This will be
used to synchronize issue/completion against timeout by later patches,
which will also add the comments.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Move the RCU vs SRCU logic into lock/unlock helpers, which makes
the actual functional bits within the locked region much easier
to read.
tj: Reordered in front of timeout revamp patches and added the missing
blk_mq_run_hw_queue() conversion.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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On scheduler init, a reference to the root group, and a reference to
its corresponding blkg are taken for the oom queue. Yet these
references are not released on scheduler exit, which prevents these
objects from be freed. This commit adds the missing reference
releases.
Reported-by: Davide Ferrari <davideferrari8@gmail.com>
Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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For each pair [device for which bfq is selected as I/O scheduler,
group in blkio/io], bfq maintains a corresponding bfq group. Each such
bfq group contains a set of async queues, with each async queue
created on demand, i.e., when some I/O request arrives for it. On
creation, an async queue gets an extra reference, to make sure that
the queue is not freed as long as its bfq group exists. Accordingly,
to allow the queue to be freed after the group exited, this extra
reference must released on group exit.
The above holds also for a bfq root group, i.e., for the bfq group
corresponding to the root blkio/io root for a given device. Yet, by
mistake, the references to the existing async queues of a root group
are not released when the latter exits. This causes a memory leak when
the instance of bfq for a given device exits. In a similar vein,
bfqg_stats_xfer_dead is not executed for a root group.
This commit fixes bfq_pd_offline so that the latter executes the above
missing operations for a root group too.
Reported-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Reported-by: Guoqing Jiang <gqjiang@suse.com>
Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Signed-off-by: Davide Ferrari <davideferrari8@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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HW queues may be unmapped in some cases, such as blk_mq_update_nr_hw_queues(),
then we need to check it before calling blk_mq_tag_idle(), otherwise
the following kernel oops can be triggered, so fix it by checking if
the hw queue is unmapped since it doesn't make sense to idle the tags
any more after hw queues are unmapped.
[ 440.771298] Workqueue: nvme-wq nvme_rdma_del_ctrl_work [nvme_rdma]
[ 440.779104] task: ffff894bae755ee0 ti: ffff893bf9bc8000 task.ti: ffff893bf9bc8000
[ 440.788359] RIP: 0010:[<ffffffffb730e2b4>] [<ffffffffb730e2b4>] __blk_mq_tag_idle+0x24/0x40
[ 440.798697] RSP: 0018:ffff893bf9bcbd10 EFLAGS: 00010286
[ 440.805538] RAX: 0000000000000000 RBX: ffff895bb131dc00 RCX: 000000000000011f
[ 440.814426] RDX: 00000000ffffffff RSI: 0000000000000120 RDI: ffff895bb131dc00
[ 440.823301] RBP: ffff893bf9bcbd10 R08: 000000000001b860 R09: 4a51d361c00c0000
[ 440.832193] R10: b5907f32b4cc7003 R11: ffffd6cabfb57000 R12: ffff894bafd1e008
[ 440.841091] R13: 0000000000000001 R14: ffff895baf770000 R15: 0000000000000080
[ 440.849988] FS: 0000000000000000(0000) GS:ffff894bbdcc0000(0000) knlGS:0000000000000000
[ 440.859955] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 440.867274] CR2: 0000000000000008 CR3: 000000103d098000 CR4: 00000000001407e0
[ 440.876169] Call Trace:
[ 440.879818] [<ffffffffb7309d68>] blk_mq_exit_hctx+0xd8/0xe0
[ 440.887051] [<ffffffffb730dc40>] blk_mq_free_queue+0xf0/0x160
[ 440.894465] [<ffffffffb72ff679>] blk_cleanup_queue+0xd9/0x150
[ 440.901881] [<ffffffffc08a802b>] nvme_ns_remove+0x5b/0xb0 [nvme_core]
[ 440.910068] [<ffffffffc08a811b>] nvme_remove_namespaces+0x3b/0x60 [nvme_core]
[ 440.919026] [<ffffffffc08b817b>] __nvme_rdma_remove_ctrl+0x2b/0xb0 [nvme_rdma]
[ 440.928079] [<ffffffffc08b8237>] nvme_rdma_del_ctrl_work+0x17/0x20 [nvme_rdma]
[ 440.937126] [<ffffffffb70ab58a>] process_one_work+0x17a/0x440
[ 440.944517] [<ffffffffb70ac3a8>] worker_thread+0x278/0x3c0
[ 440.951607] [<ffffffffb70ac130>] ? manage_workers.isra.24+0x2a0/0x2a0
[ 440.959760] [<ffffffffb70b352f>] kthread+0xcf/0xe0
[ 440.966055] [<ffffffffb70b3460>] ? insert_kthread_work+0x40/0x40
[ 440.973715] [<ffffffffb76d8658>] ret_from_fork+0x58/0x90
[ 440.980586] [<ffffffffb70b3460>] ? insert_kthread_work+0x40/0x40
[ 440.988229] Code: 5b 41 5c 5d c3 66 90 0f 1f 44 00 00 48 8b 87 20 01 00 00 f0 0f ba 77 40 01 19 d2 85 d2 75 08 c3 0f 1f 80 00 00 00 00 55 48 89 e5 <f0> ff 48 08 48 8d 78 10 e8 7f 0f 05 00 5d c3 0f 1f 00 66 2e 0f
[ 441.011620] RIP [<ffffffffb730e2b4>] __blk_mq_tag_idle+0x24/0x40
[ 441.019301] RSP <ffff893bf9bcbd10>
[ 441.024052] CR2: 0000000000000008
Reported-by: Zhang Yi <yizhan@redhat.com>
Tested-by: Zhang Yi <yizhan@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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In both elevator_switch_mq() and blk_mq_update_nr_hw_queues(), sched tags
can be allocated, and q->nr_hw_queue is used, and race is inevitable, for
example: blk_mq_init_sched() may trigger use-after-free on hctx, which is
freed in blk_mq_realloc_hw_ctxs() when nr_hw_queues is decreased.
This patch fixes the race be holding q->sysfs_lock.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Tested-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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blk_mq_pci_map_queues() may not map one CPU into any hw queue, but its
previous map isn't cleared yet, and may point to one stale hw queue
index.
This patch fixes the following issue by clearing the mapping table before
setting it up in blk_mq_pci_map_queues().
This patches fixes this following issue reported by Zhang Yi:
[ 101.202734] BUG: unable to handle kernel NULL pointer dereference at 0000000094d3013f
[ 101.211487] IP: blk_mq_map_swqueue+0xbc/0x200
[ 101.216346] PGD 0 P4D 0
[ 101.219171] Oops: 0000 [#1] SMP
[ 101.222674] Modules linked in: sunrpc ipmi_ssif vfat fat intel_rapl sb_edac x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel intel_cstate intel_uncore mxm_wmi intel_rapl_perf iTCO_wdt ipmi_si ipmi_devintf pcspkr iTCO_vendor_support sg dcdbas ipmi_msghandler wmi mei_me lpc_ich shpchp mei acpi_power_meter dm_multipath ip_tables xfs libcrc32c sd_mod mgag200 i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops ttm drm ahci libahci crc32c_intel libata tg3 nvme nvme_core megaraid_sas ptp i2c_core pps_core dm_mirror dm_region_hash dm_log dm_mod
[ 101.284881] CPU: 0 PID: 504 Comm: kworker/u25:5 Not tainted 4.15.0-rc2 #1
[ 101.292455] Hardware name: Dell Inc. PowerEdge R730xd/072T6D, BIOS 2.5.5 08/16/2017
[ 101.301001] Workqueue: nvme-wq nvme_reset_work [nvme]
[ 101.306636] task: 00000000f2c53190 task.stack: 000000002da874f9
[ 101.313241] RIP: 0010:blk_mq_map_swqueue+0xbc/0x200
[ 101.318681] RSP: 0018:ffffc9000234fd70 EFLAGS: 00010282
[ 101.324511] RAX: ffff88047ffc9480 RBX: ffff88047e130850 RCX: 0000000000000000
[ 101.332471] RDX: ffffe8ffffd40580 RSI: ffff88047e509b40 RDI: ffff88046f37a008
[ 101.340432] RBP: 000000000000000b R08: ffff88046f37a008 R09: 0000000011f94280
[ 101.348392] R10: ffff88047ffd4d00 R11: 0000000000000000 R12: ffff88046f37a008
[ 101.356353] R13: ffff88047e130f38 R14: 000000000000000b R15: ffff88046f37a558
[ 101.364314] FS: 0000000000000000(0000) GS:ffff880277c00000(0000) knlGS:0000000000000000
[ 101.373342] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 101.379753] CR2: 0000000000000098 CR3: 000000047f409004 CR4: 00000000001606f0
[ 101.387714] Call Trace:
[ 101.390445] blk_mq_update_nr_hw_queues+0xbf/0x130
[ 101.395791] nvme_reset_work+0x6f4/0xc06 [nvme]
[ 101.400848] ? pick_next_task_fair+0x290/0x5f0
[ 101.405807] ? __switch_to+0x1f5/0x430
[ 101.409988] ? put_prev_entity+0x2f/0xd0
[ 101.414365] process_one_work+0x141/0x340
[ 101.418836] worker_thread+0x47/0x3e0
[ 101.422921] kthread+0xf5/0x130
[ 101.426424] ? rescuer_thread+0x380/0x380
[ 101.430896] ? kthread_associate_blkcg+0x90/0x90
[ 101.436048] ret_from_fork+0x1f/0x30
[ 101.440034] Code: 48 83 3c ca 00 0f 84 2b 01 00 00 48 63 cd 48 8b 93 10 01 00 00 8b 0c 88 48 8b 83 20 01 00 00 4a 03 14 f5 60 04 af 81 48 8b 0c c8 <48> 8b 81 98 00 00 00 f0 4c 0f ab 30 8b 81 f8 00 00 00 89 42 44
[ 101.461116] RIP: blk_mq_map_swqueue+0xbc/0x200 RSP: ffffc9000234fd70
[ 101.468205] CR2: 0000000000000098
[ 101.471907] ---[ end trace 5fe710f98228a3ca ]---
[ 101.482489] Kernel panic - not syncing: Fatal exception
[ 101.488505] Kernel Offset: disabled
[ 101.497752] ---[ end Kernel panic - not syncing: Fatal exception
Reviewed-by: Christoph Hellwig <hch@lst.de>
Suggested-by: Christoph Hellwig <hch@lst.de>
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Tested-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Dispatch may still be in-progress after queue is frozen, so we have to
quiesce queue before switching IO scheduler and updating nr_requests.
Also when switching io schedulers, blk_mq_run_hw_queue() may still be
called somewhere(such as from nvme_reset_work()), and io scheduler's
per-hctx data may not be setup yet, so cause oops even inside
blk_mq_hctx_has_pending(), such as it can be run just between:
ret = e->ops.mq.init_sched(q, e);
AND
ret = e->ops.mq.init_hctx(hctx, i)
inside blk_mq_init_sched().
This reverts commit 7a148c2fcff8330(block: don't call blk_mq_quiesce_queue()
after queue is frozen) basically, and makes sure blk_mq_hctx_has_pending
won't be called if queue is quiesced.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Fixes: 7a148c2fcff83309(block: don't call blk_mq_quiesce_queue() after queue is frozen)
Reported-by: Yi Zhang <yi.zhang@redhat.com>
Tested-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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After queue is frozen, dispatch still may happen, for example:
1) requests are submitted from several contexts
2) requests from all these contexts are inserted to queue, but may dispatch
to LLD in one of these paths, but other paths sill need to move on even all
these requests are completed(that means blk_mq_freeze_queue_wait() returns
at that time)
3) dispatch after queue freezing still moves on and causes use-after-free,
because request queue is freed
This patch quiesces queue after it is frozen, and makes sure all
in-progress dispatch are completed.
This patch fixes the following kernel crash when running heavy IOs vs.
deleting device:
[ 36.719251] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
[ 36.720318] IP: kyber_has_work+0x14/0x40
[ 36.720847] PGD 254bf5067 P4D 254bf5067 PUD 255e6a067 PMD 0
[ 36.721584] Oops: 0000 [#1] PREEMPT SMP
[ 36.722105] Dumping ftrace buffer:
[ 36.722570] (ftrace buffer empty)
[ 36.723057] Modules linked in: scsi_debug ebtable_filter ebtables ip6table_filter ip6_tables tcm_loop iscsi_target_mod target_core_file target_core_iblock target_core_pscsi target_core_mod xt_CHECKSUM iptable_mangle ipt_MASQUERADE nf_nat_masquerade_ipv4 iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack libcrc32c bridge stp llc fuse iptable_filter ip_tables sd_mod sg btrfs xor zstd_decompress zstd_compress xxhash raid6_pq mptsas mptscsih bcache crc32c_intel ahci mptbase libahci serio_raw scsi_transport_sas nvme libata shpchp lpc_ich virtio_scsi nvme_core binfmt_misc dm_mod iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi null_blk configs
[ 36.733438] CPU: 2 PID: 2374 Comm: fio Not tainted 4.15.0-rc2.blk_mq_quiesce+ #714
[ 36.735143] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.9.3-1.fc25 04/01/2014
[ 36.736688] RIP: 0010:kyber_has_work+0x14/0x40
[ 36.737515] RSP: 0018:ffffc9000209bca0 EFLAGS: 00010202
[ 36.738431] RAX: 0000000000000008 RBX: ffff88025578bfc8 RCX: ffff880257bf4ed0
[ 36.739581] RDX: 0000000000000038 RSI: ffffffff81a98c6d RDI: ffff88025578bfc8
[ 36.740730] RBP: ffff880253cebfc8 R08: ffffc9000209bda0 R09: ffff8802554f3480
[ 36.741885] R10: ffffc9000209be60 R11: ffff880263f72538 R12: ffff88025573e9e8
[ 36.743036] R13: ffff88025578bfd0 R14: 0000000000000001 R15: 0000000000000000
[ 36.744189] FS: 00007f9b9bee67c0(0000) GS:ffff88027fc80000(0000) knlGS:0000000000000000
[ 36.746617] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 36.748483] CR2: 0000000000000008 CR3: 0000000254bf4001 CR4: 00000000003606e0
[ 36.750164] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 36.751455] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[ 36.752796] Call Trace:
[ 36.753992] blk_mq_do_dispatch_sched+0x7f/0xe0
[ 36.755110] blk_mq_sched_dispatch_requests+0x119/0x190
[ 36.756179] __blk_mq_run_hw_queue+0x83/0x90
[ 36.757144] __blk_mq_delay_run_hw_queue+0xaf/0x110
[ 36.758046] blk_mq_run_hw_queue+0x24/0x70
[ 36.758845] blk_mq_flush_plug_list+0x1e7/0x270
[ 36.759676] blk_flush_plug_list+0xd6/0x240
[ 36.760463] blk_finish_plug+0x27/0x40
[ 36.761195] do_io_submit+0x19b/0x780
[ 36.761921] ? entry_SYSCALL_64_fastpath+0x1a/0x7d
[ 36.762788] entry_SYSCALL_64_fastpath+0x1a/0x7d
[ 36.763639] RIP: 0033:0x7f9b9699f697
[ 36.764352] RSP: 002b:00007ffc10f991b8 EFLAGS: 00000206 ORIG_RAX: 00000000000000d1
[ 36.765773] RAX: ffffffffffffffda RBX: 00000000008f6f00 RCX: 00007f9b9699f697
[ 36.766965] RDX: 0000000000a5e6c0 RSI: 0000000000000001 RDI: 00007f9b8462a000
[ 36.768377] RBP: 0000000000000000 R08: 0000000000000001 R09: 00000000008f6420
[ 36.769649] R10: 00007f9b846e5000 R11: 0000000000000206 R12: 00007f9b795d6a70
[ 36.770807] R13: 00007f9b795e4140 R14: 00007f9b795e3fe0 R15: 0000000100000000
[ 36.771955] Code: 83 c7 10 e9 3f 68 d1 ff 0f 1f 44 00 00 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 8b 97 b0 00 00 00 48 8d 42 08 48 83 c2 38 <48> 3b 00 74 06 b8 01 00 00 00 c3 48 3b 40 08 75 f4 48 83 c0 10
[ 36.775004] RIP: kyber_has_work+0x14/0x40 RSP: ffffc9000209bca0
[ 36.776012] CR2: 0000000000000008
[ 36.776690] ---[ end trace 4045cbce364ff2a4 ]---
[ 36.777527] Kernel panic - not syncing: Fatal exception
[ 36.778526] Dumping ftrace buffer:
[ 36.779313] (ftrace buffer empty)
[ 36.780081] Kernel Offset: disabled
[ 36.780877] ---[ end Kernel panic - not syncing: Fatal exception
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org
Tested-by: Yi Zhang <yi.zhang@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Don't pass in the hardware queue to __dd_dispatch_request(), since it
leads the reader to believe that we are returning a request for that
specific hardware queue. That's not how mq-deadline works, the state
for determining which request to serve next is shared across all
hardware queues for a device.
Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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In this case, 'sectors' can't be zero at all, so remove the check
and let the bio be split.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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