• Bart Van Assche's avatar
    IB/srp: Fix deadlock between host removal and multipathd · 1b29db8c
    Bart Van Assche authored
    commit bcc05910 upstream.
    
    If scsi_remove_host() is invoked after a SCSI device has been blocked,
    if the fast_io_fail_tmo or dev_loss_tmo work gets scheduled on the
    workqueue executing srp_remove_work() and if an I/O request is
    scheduled after the SCSI device had been blocked by e.g. multipathd
    then the following deadlock can occur:
    
        kworker/6:1     D ffff880831f3c460     0   195      2 0x00000000
        Call Trace:
         [<ffffffff814aafd9>] schedule+0x29/0x70
         [<ffffffff814aa0ef>] schedule_timeout+0x10f/0x2a0
         [<ffffffff8105af6f>] msleep+0x2f/0x40
         [<ffffffff8123b0ae>] __blk_drain_queue+0x4e/0x180
         [<ffffffff8123d2d5>] blk_cleanup_queue+0x225/0x230
         [<ffffffffa0010732>] __scsi_remove_device+0x62/0xe0 [scsi_mod]
         [<ffffffffa000ed2f>] scsi_forget_host+0x6f/0x80 [scsi_mod]
         [<ffffffffa0002eba>] scsi_remove_host+0x7a/0x130 [scsi_mod]
         [<ffffffffa07cf5c5>] srp_remove_work+0x95/0x180 [ib_srp]
         [<ffffffff8106d7aa>] process_one_work+0x1ea/0x6c0
         [<ffffffff8106dd9b>] worker_thread+0x11b/0x3a0
         [<ffffffff810758bd>] kthread+0xed/0x110
         [<ffffffff814b972c>] ret_from_fork+0x7c/0xb0
        multipathd      D ffff880096acc460     0  5340      1 0x00000000
        Call Trace:
         [<ffffffff814aafd9>] schedule+0x29/0x70
         [<ffffffff814aa0ef>] schedule_timeout+0x10f/0x2a0
         [<ffffffff814ab79b>] io_schedule_timeout+0x9b/0xf0
         [<ffffffff814abe1c>] wait_for_completion_io_timeout+0xdc/0x110
         [<ffffffff81244b9b>] blk_execute_rq+0x9b/0x100
         [<ffffffff8124f665>] sg_io+0x1a5/0x450
         [<ffffffff8124fd21>] scsi_cmd_ioctl+0x2a1/0x430
         [<ffffffff8124fef2>] scsi_cmd_blk_ioctl+0x42/0x50
         [<ffffffffa00ec97e>] sd_ioctl+0xbe/0x140 [sd_mod]
         [<ffffffff8124bd04>] blkdev_ioctl+0x234/0x840
         [<ffffffff811cb491>] block_ioctl+0x41/0x50
         [<ffffffff811a0df0>] do_vfs_ioctl+0x300/0x520
         [<ffffffff811a1051>] SyS_ioctl+0x41/0x80
         [<ffffffff814b9962>] tracesys+0xd0/0xd5
    
    Fix this by scheduling removal work on another workqueue than the
    transport layer timers.
    Signed-off-by: default avatarBart Van Assche <bvanassche@acm.org>
    Reviewed-by: default avatarSagi Grimberg <sagig@mellanox.com>
    Reviewed-by: default avatarDavid Dillow <dave@thedillows.org>
    Cc: Sebastian Parschauer <sebastian.riemer@profitbricks.com>
    Signed-off-by: default avatarRoland Dreier <roland@purestorage.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    1b29db8c
ib_srp.c 88.2 KB