• Bart Van Assche's avatar
    Defer processing of REQ_PREEMPT requests for blocked devices · 3e01cca3
    Bart Van Assche authored
    commit bba0bdd7ad4713d82338bcd9b72d57e9335a664b upstream.
    
    SCSI transport drivers and SCSI LLDs block a SCSI device if the
    transport layer is not operational. This means that in this state
    no requests should be processed, even if the REQ_PREEMPT flag has
    been set. This patch avoids that a rescan shortly after a cable
    pull sporadically triggers the following kernel oops:
    
    BUG: unable to handle kernel paging request at ffffc9001a6bc084
    IP: [<ffffffffa04e08f2>] mlx4_ib_post_send+0xd2/0xb30 [mlx4_ib]
    Process rescan-scsi-bus (pid: 9241, threadinfo ffff88053484a000, task ffff880534aae100)
    Call Trace:
     [<ffffffffa0718135>] srp_post_send+0x65/0x70 [ib_srp]
     [<ffffffffa071b9df>] srp_queuecommand+0x1cf/0x3e0 [ib_srp]
     [<ffffffffa0001ff1>] scsi_dispatch_cmd+0x101/0x280 [scsi_mod]
     [<ffffffffa0009ad1>] scsi_request_fn+0x411/0x4d0 [scsi_mod]
     [<ffffffff81223b37>] __blk_run_queue+0x27/0x30
     [<ffffffff8122a8d2>] blk_execute_rq_nowait+0x82/0x110
     [<ffffffff8122a9c2>] blk_execute_rq+0x62/0xf0
     [<ffffffffa000b0e8>] scsi_execute+0xe8/0x190 [scsi_mod]
     [<ffffffffa000b2f3>] scsi_execute_req+0xa3/0x130 [scsi_mod]
     [<ffffffffa000c1aa>] scsi_probe_lun+0x17a/0x450 [scsi_mod]
     [<ffffffffa000ce86>] scsi_probe_and_add_lun+0x156/0x480 [scsi_mod]
     [<ffffffffa000dc2f>] __scsi_scan_target+0xdf/0x1f0 [scsi_mod]
     [<ffffffffa000dfa3>] scsi_scan_host_selected+0x183/0x1c0 [scsi_mod]
     [<ffffffffa000edfb>] scsi_scan+0xdb/0xe0 [scsi_mod]
     [<ffffffffa000ee13>] store_scan+0x13/0x20 [scsi_mod]
     [<ffffffff811c8d9b>] sysfs_write_file+0xcb/0x160
     [<ffffffff811589de>] vfs_write+0xce/0x140
     [<ffffffff81158b53>] sys_write+0x53/0xa0
     [<ffffffff81464592>] system_call_fastpath+0x16/0x1b
     [<00007f611c9d9300>] 0x7f611c9d92ff
    Reported-by: default avatarMax Gurtuvoy <maxg@mellanox.com>
    Signed-off-by: default avatarBart Van Assche <bart.vanassche@sandisk.com>
    Reviewed-by: default avatarMike Christie <michaelc@cs.wisc.edu>
    Signed-off-by: default avatarJames Bottomley <JBottomley@Odin.com>
    Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
    3e01cca3
scsi_lib.c 67 KB