1. 07 Dec, 2018 3 commits
    • Israel Rukshin's avatar
      nvmet-rdma: fix response use after free · d7dcdf9d
      Israel Rukshin authored
      nvmet_rdma_release_rsp() may free the response before using it at error
      Fixes: 8407879c
       ("nvmet-rdma: fix possible bogus dereference under heavy load")
      Signed-off-by: default avatarIsrael Rukshin <israelr@mellanox.com>
      Reviewed-by: default avatarSagi Grimberg <sagi@grimberg.me>
      Reviewed-by: default avatarMax Gurtovoy <maxg@mellanox.com>
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
    • James Smart's avatar
      nvme: validate controller state before rescheduling keep alive · 86880d64
      James Smart authored
      Delete operations are seeing NULL pointer references in call_timer_fn.
      Tracking these back, the timer appears to be the keep alive timer.
      nvme_keep_alive_work() which is tied to the timer that is cancelled
      by nvme_stop_keep_alive(), simply starts the keep alive io but doesn't
      wait for it's completion. So nvme_stop_keep_alive() only stops a timer
      when it's pending. When a keep alive is in flight, there is no timer
      running and the nvme_stop_keep_alive() will have no affect on the keep
      alive io. Thus, if the io completes successfully, the keep alive timer
      will be rescheduled.   In the failure case, delete is called, the
      controller state is changed, the nvme_stop_keep_alive() is called while
      the io is outstanding, and the delete path continues on. The keep
      alive happens to successfully complete before the delete paths mark it
      as aborted as part of the queue termination, so the timer is restarted.
      The delete paths then tear down the controller, and later on the timer
      code fires and the timer entry is now corrupt.
      Fix by validating the controller state before rescheduling the keep
      alive. Testing with the fix has confirmed the condition above was hit.
      Signed-off-by: default avatarJames Smart <jsmart2021@gmail.com>
      Reviewed-by: default avatarSagi Grimberg <sagi@grimberg.me>
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
    • Paolo Valente's avatar
      block, bfq: fix decrement of num_active_groups · ba7aeae5
      Paolo Valente authored
      Since commit '2d29c9f8 ("block, bfq: improve asymmetric scenarios
      detection")', if there are process groups with I/O requests waiting for
      completion, then BFQ tags the scenario as 'asymmetric'. This detection
      is needed for preserving service guarantees (for details, see comments
      on the computation * of the variable asymmetric_scenario in the
      function bfq_better_to_idle).
      Unfortunately, commit '2d29c9f8 ("block, bfq: improve asymmetric
      scenarios detection")' contains an error exactly in the updating of
      the number of groups with I/O requests waiting for completion: if a
      group has more than one descendant process, then the above number of
      groups, which is renamed from num_active_groups to a more appropriate
      num_groups_with_pending_reqs by this commit, may happen to be wrongly
      decremented multiple times, namely every time one of the descendant
      processes gets all its pending I/O requests completed.
      A correct, complete solution should work as follows. Consider a group
      that is inactive, i.e., that has no descendant process with pending
      I/O inside BFQ queues. Then suppose that num_groups_with_pending_reqs
      is still accounting for this group, because the group still has some
      descendant process with some I/O request still in
      flight. num_groups_with_pending_reqs should be decremented when the
      in-flight request of the last descendant process is finally completed
      (assuming that nothing else has changed for the group in the meantime,
      in terms of composition of the group and active/inactive state of
      child groups and processes). To accomplish this, an additional
      pending-request counter must be added to entities, and must be
      updated correctly.
      To avoid this additional field and operations, this commit resorts to
      the following tradeoff between simplicity and accuracy: for an
      inactive group that is still counted in num_groups_with_pending_reqs,
      this commit decrements num_groups_with_pending_reqs when the first
      descendant process of the group remains with no request waiting for
      This simplified scheme provides a fix to the unbalanced decrements
      introduced by 2d29c9f8. Since this error was also caused by lack
      of comments on this non-trivial issue, this commit also adds related
      Fixes: 2d29c9f8
       ("block, bfq: improve asymmetric scenarios detection")
      Reported-by: default avatarSteven Barrett <steven@liquorix.net>
      Tested-by: default avatarSteven Barrett <steven@liquorix.net>
      Tested-by: default avatarLucjan Lucjanov <lucjan.lucjanov@gmail.com>
      Reviewed-by: default avatarFederico Motta <federico@willer.it>
      Signed-off-by: default avatarPaolo Valente <paolo.valente@linaro.org>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
  2. 05 Dec, 2018 1 commit
    • Jens Axboe's avatar
      blk-mq: fix corruption with direct issue · ffe81d45
      Jens Axboe authored
      If we attempt a direct issue to a SCSI device, and it returns BUSY, then
      we queue the request up normally. However, the SCSI layer may have
      already setup SG tables etc for this particular command. If we later
      merge with this request, then the old tables are no longer valid. Once
      we issue the IO, we only read/write the original part of the request,
      not the new state of it.
      This causes data corruption, and is most often noticed with the file
      system complaining about the just read data being invalid:
      [  235.934465] EXT4-fs error (device sda1): ext4_iget:4831: inode #7142: comm dpkg-query: bad extra_isize 24937 (inode size 256)
      because most of it is garbage...
      This doesn't happen from the normal issue path, as we will simply defer
      the request to the hardware queue dispatch list if we fail. Once it's on
      the dispatch list, we never merge with it.
      Fix this from the direct issue path by flagging the request as
      REQ_NOMERGE so we don't change the size of it before issue.
      See also:
      Tested-by: default avatarGuenter Roeck <linux@roeck-us.net>
      Fixes: 6ce3dd6e
       ("blk-mq: issue directly if hw queue isn't busy in case of 'none'")
      Cc: stable@vger.kernel.org
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
  3. 03 Dec, 2018 1 commit
  4. 30 Nov, 2018 6 commits
    • Jens Axboe's avatar
      Merge branch 'nvme-4.20' of git://git.infradead.org/nvme into for-linus · 1c9b357c
      Jens Axboe authored
      Pull NVMe fixes from Christoph:
      "Various fixlets all over."
      * 'nvme-4.20' of git://git.infradead.org/nvme:
        nvme-rdma: fix double freeing of async event data
        nvme: flush namespace scanning work just before removing namespaces
        nvme: warn when finding multi-port subsystems without multipathing enabled
        nvme-pci: fix surprise removal
        nvme-fc: initialize nvme_req(rq)->ctrl after calling __nvme_fc_init_request()
        nvme: Free ctrl device name on init failure
    • Ming Lei's avatar
      block: fix single range discard merge · 2a5cf35c
      Ming Lei authored
      There are actually two kinds of discard merge:
      - one is the normal discard merge, just like normal read/write request,
      and call it single-range discard
      - another is the multi-range discard, queue_max_discard_segments(rq->q) > 1
      For the former case, queue_max_discard_segments(rq->q) is 1, and we
      should handle this kind of discard merge like the normal read/write
      This patch fixes the following kernel panic issue[1], which is caused by
      not removing the single-range discard request from elevator queue.
      Guangwu has one raid discard test case, in which this issue is a bit
      easier to trigger, and I verified that this patch can fix the kernel
      panic issue in Guangwu's test case.
      [1] kernel panic log from Jens's report
       BUG: unable to handle kernel NULL pointer dereference at 0000000000000148
       PGD 0 P4D 0.
       Oops: 0000 [#1] SMP PTI
       CPU: 37 PID: 763 Comm: kworker/37:1H Not tainted \
      4.20.0-rc3-00649-ge64d9a554a91-dirty #14  Hardware name: Wiwynn \
      Leopard-Orv2/Leopard-DDR BW, BIOS LBM08   03/03/2017       Workqueue: kblockd \
      blk_mq_run_work_fn                                            RIP: \
      0010:blk_mq_get_driver_tag+0x81/0x120                                       Code: 24 \
      10 48 89 7c 24 20 74 21 83 fa ff 0f 95 c0 48 8b 4c 24 28 65 48 33 0c 25 28 00 00 00 \
      0f 85 96 00 00 00 48 83 c4 30 5b 5d c3 <48> 8b 87 48 01 00 00 8b 40 04 39 43 20 72 37 \
      f6 87 b0 00 00 00 02  RSP: 0018:ffffc90004aabd30 EFLAGS: 00010246                     \
        RAX: 0000000000000003 RBX: ffff888465ea1300 RCX: ffffc90004aabde8
       RDX: 00000000ffffffff RSI: ffffc90004aabde8 RDI: 0000000000000000
       RBP: 0000000000000000 R08: ffff888465ea1348 R09: 0000000000000000
       R10: 0000000000001000 R11: 00000000ffffffff R12: ffff888465ea1300
       R13: 0000000000000000 R14: ffff888465ea1348 R15: ffff888465d10000
       FS:  0000000000000000(0000) GS:ffff88846f9c0000(0000) knlGS:0000000000000000
       CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
       CR2: 0000000000000148 CR3: 000000000220a003 CR4: 00000000003606e0
       DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
       DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
       Call Trace:
        ? elv_rb_del+0x11/0x30
        ? process_one_work+0x350/0x350
        ? kthread_destroy_worker+0x50/0x50
       Modules linked in: sb_edac x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel \
      kvm switchtec irqbypass iTCO_wdt iTCO_vendor_support efivars cdc_ether usbnet mii \
      cdc_acm i2c_i801 lpc_ich mfd_core ipmi_si ipmi_devintf ipmi_msghandler acpi_cpufreq \
      button sch_fq_codel nfsd nfs_acl lockd grace auth_rpcgss oid_registry sunrpc nvme \
      nvme_core fuse sg loop efivarfs autofs4  CR2: 0000000000000148                        \
       ---[ end trace 340a1fb996df1b9b ]---
       RIP: 0010:blk_mq_get_driver_tag+0x81/0x120
       Code: 24 10 48 89 7c 24 20 74 21 83 fa ff 0f 95 c0 48 8b 4c 24 28 65 48 33 0c 25 28 \
      00 00 00 0f 85 96 00 00 00 48 83 c4 30 5b 5d c3 <48> 8b 87 48 01 00 00 8b 40 04 39 43 \
      20 72 37 f6 87 b0 00 00 00 02
      Fixes: 445251d0
       ("blk-mq: fix discard merge with scheduler attached")
      Reported-by: default avatarJens Axboe <axboe@kernel.dk>
      Cc: Guangwu Zhang <guazhang@redhat.com>
      Cc: Christoph Hellwig <hch@lst.de>
      Cc: Jianchao Wang <jianchao.w.wang@oracle.com>
      Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
    • Prabhath Sajeepa's avatar
      nvme-rdma: fix double freeing of async event data · 6344d02d
      Prabhath Sajeepa authored
      Some error paths in configuration of admin queue free data buffer
      associated with async request SQE without resetting the data buffer
      pointer to NULL, This buffer is also freed up again if the controller
      is shutdown or reset.
      Signed-off-by: default avatarPrabhath Sajeepa <psajeepa@purestorage.com>
      Reviewed-by: default avatarRoland Dreier <roland@purestorage.com>
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
    • Sagi Grimberg's avatar
      nvme: flush namespace scanning work just before removing namespaces · f6c8e432
      Sagi Grimberg authored
      nvme_stop_ctrl can be called also for reset flow and there is no need to
      flush the scan_work as namespaces are not being removed. This can cause
      deadlock in rdma, fc and loop drivers since nvme_stop_ctrl barriers
      before controller teardown (and specifically I/O cancellation of the
      scan_work itself) takes place, but the scan_work will be blocked anyways
      so there is no need to flush it.
      Instead, move scan_work flush to nvme_remove_namespaces() where it really
      needs to flush.
      Reported-by: default avatarMing Lei <ming.lei@redhat.com>
      Signed-off-by: default avatarSagi Grimberg <sagi@grimberg.me>
      Reviewed-by: default avatarKeith Busch <keith.busch@intel.com>
      Reviewed by: James Smart <jsmart2021@gmail.com>
      Tested-by: default avatarEwan D. Milne <emilne@redhat.com>
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
    • Christoph Hellwig's avatar
      nvme: warn when finding multi-port subsystems without multipathing enabled · 14a1336e
      Christoph Hellwig authored
      Without CONFIG_NVME_MULTIPATH enabled a multi-port subsystem might
      show up as invididual devices and cause problems, warn about it.
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
      Reviewed-by: default avatarSagi Grimberg <sagi@grimberg.me>
    • Maximilian Heyne's avatar
      fs: fix lost error code in dio_complete · 41e817bc
      Maximilian Heyne authored
      commit e2592217 ("fs: simplify the
      generic_write_sync prototype") reworked callers of generic_write_sync(),
      and ended up dropping the error return for the directio path. Prior to
      that commit, in dio_complete(), an error would be bubbled up the stack,
      but after that commit, errors passed on to dio_complete were eaten up.
      This was reported on the list earlier, and a fix was proposed in
      https://lore.kernel.org/lkml/20160921141539.GA17898@infradead.org/, but
      never followed up with.  We recently hit this bug in our testing where
      fencing io errors, which were previously erroring out with EIO, were
      being returned as success operations after this commit.
      The fix proposed on the list earlier was a little short -- it would have
      still called generic_write_sync() in case `ret` already contained an
      error. This fix ensures generic_write_sync() is only called when there's
      no pending error in the write. Additionally, transferred is replaced
      with ret to bring this code in line with other callers.
      Fixes: e2592217
       ("fs: simplify the generic_write_sync prototype")
      Reported-by: default avatarRavi Nankani <rnankani@amazon.com>
      Signed-off-by: default avatarMaximilian Heyne <mheyne@amazon.de>
      Reviewed-by: default avatarChristoph Hellwig <hch@lst.de>
      CC: Torsten Mehlan <tomeh@amazon.de>
      CC: Uwe Dannowski <uwed@amazon.de>
      CC: Amit Shah <aams@amazon.de>
      CC: David Woodhouse <dwmw@amazon.co.uk>
      CC: stable@vger.kernel.org
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
  5. 27 Nov, 2018 3 commits
    • Igor Konopko's avatar
      nvme-pci: fix surprise removal · 751a0cc0
      Igor Konopko authored
      When a PCIe NVMe device is not present, nvme_dev_remove_admin() calls
      blk_cleanup_queue() on the admin queue, which frees the hctx for that
      queue.  Moments later, on the same path nvme_kill_queues() calls
      blk_mq_unquiesce_queue() on admin queue and tries to access hctx of it,
      which leads to following OOPS:
      Oops: 0000 [#1] SMP PTI
      RIP: 0010:sbitmap_any_bit_set+0xb/0x40
      Call Trace:
      Fixes: cb4bfda6
       ("nvme-pci: fix hot removal during error handling")
      Signed-off-by: default avatarIgor Konopko <igor.j.konopko@intel.com>
      Reviewed-by: default avatarKeith Busch <keith.busch@intel.com>
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
    • Ewan D. Milne's avatar
      nvme-fc: initialize nvme_req(rq)->ctrl after calling __nvme_fc_init_request() · dfa74422
      Ewan D. Milne authored
      __nvme_fc_init_request() invokes memset() on the nvme_fcp_op_w_sgl structure, which
      NULLed-out the nvme_req(req)->ctrl field previously set by nvme_fc_init_request().
      This apparently was not referenced until commit faf4a44fff ("nvme: support traffic
      based keep-alive") which now results in a crash in nvme_complete_rq():
      [ 8386.897130] RIP: 0010:panic+0x220/0x26c
      [ 8386.901406] Code: 83 3d 6f ee 72 01 00 74 05 e8 e8 54 02 00 48 c7 c6 40 fd 5b b4 48 c7 c7 d8 8d c6 b3 31e
      [ 8386.922359] RSP: 0018:ffff99650019fc40 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
      [ 8386.930804] RAX: 0000000000000046 RBX: 0000000000000000 RCX: 0000000000000006
      [ 8386.938764] RDX: 0000000000000000 RSI: 0000000000000082 RDI: ffff8e325f8168b0
      [ 8386.946725] RBP: ffff99650019fcb0 R08: 0000000000000000 R09: 00000000000004f8
      [ 8386.954687] R10: 0000000000000000 R11: ffff99650019f9b8 R12: ffffffffb3c55f3c
      [ 8386.962648] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000001
      [ 8386.970613]  oops_end+0xd1/0xe0
      [ 8386.974116]  no_context+0x1b2/0x3c0
      [ 8386.978006]  do_page_fault+0x32/0x140
      [ 8386.982090]  page_fault+0x1e/0x30
      [ 8386.985786] RIP: 0010:nvme_complete_rq+0x65/0x1d0 [nvme_core]
      [ 8386.992195] Code: 41 bc 03 00 00 00 74 16 0f 86 c3 00 00 00 66 3d 83 00 41 bc 06 00 00 00 0f 85 e7 00 000
      [ 8387.013147] RSP: 0018:ffff99650019fe18 EFLAGS: 00010246
      [ 8387.018973] RAX: 0000000000000000 RBX: ffff8e322ae51280 RCX: 0000000000000001
      [ 8387.026935] RDX: 0000000000000400 RSI: 0000000000000001 RDI: ffff8e322ae51280
      [ 8387.034897] RBP: ffff8e322ae51280 R08: 0000000000000000 R09: ffffffffb2f0b890
      [ 8387.042859] R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
      [ 8387.050821] R13: 0000000000000100 R14: 0000000000000004 R15: ffff8e2b0446d990
      [ 8387.058782]  ? swiotlb_unmap_page+0x40/0x40
      [ 8387.063448]  nvme_fc_complete_rq+0x2d/0x70 [nvme_fc]
      [ 8387.068986]  blk_done_softirq+0xa1/0xd0
      [ 8387.073264]  __do_softirq+0xd6/0x2a9
      [ 8387.077251]  run_ksoftirqd+0x26/0x40
      [ 8387.081238]  smpboot_thread_fn+0x10e/0x160
      [ 8387.085807]  kthread+0xf8/0x130
      [ 8387.089309]  ? sort_range+0x20/0x20
      [ 8387.093198]  ? kthread_stop+0x110/0x110
      [ 8387.097475]  ret_from_fork+0x35/0x40
      [ 8387.101462] ---[ end trace 7106b0adf5e422f8 ]---
      Fixes: faf4a44fff ("nvme: support traffic based keep-alive")
      Signed-off-by: default avatarEwan D. Milne <emilne@redhat.com>
      Reviewed-by: default avatarHannes Reinecke <hare@suse.com>
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
    • Keith Busch's avatar
      nvme: Free ctrl device name on init failure · d6a2b953
      Keith Busch authored
      Free the kobject name that was allocated for the controller device on
      failure rather than its parent.
      Fixes: d22524a4
       ("nvme: switch controller refcounting to use struct device")
      Signed-off-by: default avatarKeith Busch <keith.busch@intel.com>
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
  6. 21 Nov, 2018 1 commit
  7. 15 Nov, 2018 1 commit
    • James Smart's avatar
      nvme-fc: resolve io failures during connect · 4cff280a
      James Smart authored
      If an io error occurs on an io issued while connecting, recovery
      of the io falls flat as the state checking ends up nooping the error
      Create an err_work work item that is scheduled upon an io error while
      connecting. The work thread terminates all io on all queues and marks
      the queues as not connected.  The termination of the io will return
      back to the callee, which will then back out of the connection attempt
      and will reschedule, if possible, the connection attempt.
      The changes:
      - in case there are several commands hitting the error handler, a
        state flag is kept so that the error work is only scheduled once,
        on the first error. The subsequent errors can be ignored.
      - The calling sequence to stop keep alive and terminate the queues
        and their io is lifted from the reset routine. Made a small
        service routine used by both reset and err_work.
      - During debugging, found that the teardown path can reference
        an uninitialized pointer, resulting in a NULL pointer oops.
        The aen_ops weren't initialized yet. Add validation on their
        initialization before calling the teardown routine.
      Signed-off-by: default avatarJames Smart <jsmart2021@gmail.com>
      Signed-off-by: default avatarChristoph Hellwig <hch@lst.de>
  8. 14 Nov, 2018 2 commits
    • Ming Lei's avatar
      SCSI: fix queue cleanup race before queue initialization is done · 8dc765d4
      Ming Lei authored
      c2856ae2 ("blk-mq: quiesce queue before freeing queue") has
      already fixed this race, however the implied synchronize_rcu()
      in blk_mq_quiesce_queue() can slow down LUN probe a lot, so caused
      performance regression.
      Then 1311326c ("blk-mq: avoid to synchronize rcu inside blk_cleanup_queue()")
      tried to quiesce queue for avoiding unnecessary synchronize_rcu()
      only when queue initialization is done, because it is usual to see
      lots of inexistent LUNs which need to be probed.
      However, turns out it isn't safe to quiesce queue only when queue
      initialization is done. Because when one SCSI command is completed,
      the user of sending command can be waken up immediately, then the
      scsi device may be removed, meantime the run queue in scsi_end_request()
      is still in-progress, so kernel panic can be caused.
      In Red Hat QE lab, there are several reports about this kind of kernel
      panic triggered during kernel booting.
      This patch tries to address the issue by grabing one queue usage
      counter during freeing one request and the following run queue.
      Fixes: 1311326c
       ("blk-mq: avoid to synchronize rcu inside blk_cleanup_queue()")
      Cc: Andrew Jones <drjones@redhat.com>
      Cc: Bart Van Assche <bart.vanassche@wdc.com>
      Cc: linux-scsi@vger.kernel.org
      Cc: Martin K. Petersen <martin.petersen@oracle.com>
      Cc: Christoph Hellwig <hch@lst.de>
      Cc: James E.J. Bottomley <jejb@linux.vnet.ibm.com>
      Cc: stable <stable@vger.kernel.org>
      Cc: jianchao.wang <jianchao.w.wang@oracle.com>
      Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
    • Dave Chinner's avatar
      block: fix 32 bit overflow in __blkdev_issue_discard() · 4800bf7b
      Dave Chinner authored
      A discard cleanup merged into 4.20-rc2 causes fstests xfs/259 to
      fall into an endless loop in the discard code. The test is creating
      a device that is exactly 2^32 sectors in size to test mkfs boundary
      conditions around the 32 bit sector overflow region.
      mkfs issues a discard for the entire device size by default, and
      hence this throws a sector count of 2^32 into
      blkdev_issue_discard(). It takes the number of sectors to discard as
      a sector_t - a 64 bit value.
      The commit ba5d7385 ("block: cleanup __blkdev_issue_discard")
      takes this sector count and casts it to a 32 bit value before
      comapring it against the maximum allowed discard size the device
      has. This truncates away the upper 32 bits, and so if the lower 32
      bits of the sector count is zero, it starts issuing discards of
      length 0. This causes the code to fall into an endless loop, issuing
      a zero length discards over and over again on the same sector.
      Fixes: ba5d7385
       ("block: cleanup __blkdev_issue_discard")
      Tested-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
      Reviewed-by: default avatarDarrick J. Wong <darrick.wong@oracle.com>
      Signed-off-by: default avatarDave Chinner <dchinner@redhat.com>
      Killed pointless WARN_ON().
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
  9. 12 Nov, 2018 3 commits
  10. 10 Nov, 2018 1 commit
    • Jens Axboe's avatar
      floppy: fix race condition in __floppy_read_block_0() · de7b75d8
      Jens Axboe authored
      LKP recently reported a hang at bootup in the floppy code:
      [  245.678853] INFO: task mount:580 blocked for more than 120 seconds.
      [  245.679906]       Tainted: G                T 4.19.0-rc6-00172-ga9f38e1d #1
      [  245.680959] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
      [  245.682181] mount           D 6372   580      1 0x00000004
      [  245.683023] Call Trace:
      [  245.683425]  __schedule+0x2df/0x570
      [  245.683975]  schedule+0x2d/0x80
      [  245.684476]  schedule_timeout+0x19d/0x330
      [  245.685090]  ? wait_for_common+0xa5/0x170
      [  245.685735]  wait_for_common+0xac/0x170
      [  245.686339]  ? do_sched_yield+0x90/0x90
      [  245.686935]  wait_for_completion+0x12/0x20
      [  245.687571]  __floppy_read_block_0+0xfb/0x150
      [  245.688244]  ? floppy_resume+0x40/0x40
      [  245.688844]  floppy_revalidate+0x20f/0x240
      [  245.689486]  check_disk_change+0x43/0x60
      [  245.690087]  floppy_open+0x1ea/0x360
      [  245.690653]  __blkdev_get+0xb4/0x4d0
      [  245.691212]  ? blkdev_get+0x1db/0x370
      [  245.691777]  blkdev_get+0x1f3/0x370
      [  245.692351]  ? path_put+0x15/0x20
      [  245.692871]  ? lookup_bdev+0x4b/0x90
      [  245.693539]  blkdev_get_by_path+0x3d/0x80
      [  245.694165]  mount_bdev+0x2a/0x190
      [  245.694695]  squashfs_mount+0x10/0x20
      [  245.695271]  ? squashfs_alloc_inode+0x30/0x30
      [  245.695960]  mount_fs+0xf/0x90
      [  245.696451]  vfs_kern_mount+0x43/0x130
      [  245.697036]  do_mount+0x187/0xc40
      [  245.697563]  ? memdup_user+0x28/0x50
      [  245.698124]  ksys_mount+0x60/0xc0
      [  245.698639]  sys_mount+0x19/0x20
      [  245.699167]  do_int80_syscall_32+0x61/0x130
      [  245.699813]  entry_INT80_32+0xc7/0xc7
      showing that we never complete that read request. The reason is that
      the completion setup is racy - it initializes the completion event
      AFTER submitting the IO, which means that the IO could complete
      before/during the init. If it does, we are passing garbage to
      complete() and we may sleep forever waiting for the event to
      Fixes: 7b7b68bb
       ("floppy: bail out in open() if drive is not responding to block0 read")
      Reviewed-by: default avatarOmar Sandoval <osandov@fb.com>
      Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
  11. 09 Nov, 2018 10 commits
  12. 08 Nov, 2018 8 commits