path: root/block
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authorTejun Heo <>2011-10-17 13:42:43 +0200
committerGreg Kroah-Hartman <>2011-11-11 09:44:30 -0800
commit6022736e9bb4ff26f0e5556814aa43c4057e7e86 (patch)
treea2f433596ddcd4b9b77a54361727ba029dc47fd5 /block
parent819bac2f91d8ae8433bd5beb85797bb0c63cbaa2 (diff)
block: make gendisk hold a reference to its queue
commit f992ae801a7dec34a4ed99a6598bbbbfb82af4fb upstream. The following command sequence triggers an oops. # mount /dev/sdb1 /mnt # echo 1 > /sys/class/scsi_device/0\:0\:1\:0/device/delete # umount /mnt general protection fault: 0000 [#1] PREEMPT SMP CPU 2 Modules linked in: Pid: 791, comm: umount Not tainted 3.1.0-rc3-work+ #8 Bochs Bochs RIP: 0010:[<ffffffff810d0879>] [<ffffffff810d0879>] __lock_acquire+0x389/0x1d60 ... Call Trace: [<ffffffff810d2845>] lock_acquire+0x95/0x140 [<ffffffff81aed87b>] _raw_spin_lock+0x3b/0x50 [<ffffffff811573bc>] bdi_lock_two+0x5c/0x70 [<ffffffff811c2f6c>] bdev_inode_switch_bdi+0x4c/0xf0 [<ffffffff811c3fcb>] __blkdev_put+0x11b/0x1d0 [<ffffffff811c4010>] __blkdev_put+0x160/0x1d0 [<ffffffff811c40df>] blkdev_put+0x5f/0x190 [<ffffffff8118f18d>] kill_block_super+0x4d/0x80 [<ffffffff8118f4a5>] deactivate_locked_super+0x45/0x70 [<ffffffff8119003a>] deactivate_super+0x4a/0x70 [<ffffffff811ac4ad>] mntput_no_expire+0xed/0x130 [<ffffffff811acf2e>] sys_umount+0x7e/0x3a0 [<ffffffff81aeeeab>] system_call_fastpath+0x16/0x1b This is because bdev holds on to disk but disk doesn't pin the associated queue. If a SCSI device is removed while the device is still open, the sdev puts the base reference to the queue on release. When the bdev is finally released, the associated queue is already gone along with the bdi and bdev_inode_switch_bdi() ends up dereferencing already freed bdi. Even if it were not for this bug, disk not holding onto the associated queue is very unusual and error-prone. Fix it by making add_disk() take an extra reference to its queue and put it on disk_release() and ensuring that disk and its fops owner are put in that order after all accesses to the disk and queue are complete. Signed-off-by: Tejun Heo <> Cc: Jens Axboe <> Signed-off-by: Jens Axboe <> Signed-off-by: Greg Kroah-Hartman <>
Diffstat (limited to 'block')
1 files changed, 8 insertions, 0 deletions
diff --git a/block/genhd.c b/block/genhd.c
index e2f67902dd02..d261b73b9744 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -611,6 +611,12 @@ void add_disk(struct gendisk *disk)
+ /*
+ * Take an extra ref on queue which will be put on disk_release()
+ * so that it sticks around as long as @disk is there.
+ */
+ WARN_ON_ONCE(blk_get_queue(disk->queue));
retval = sysfs_create_link(&disk_to_dev(disk)->kobj, &bdi->dev->kobj,
@@ -1095,6 +1101,8 @@ static void disk_release(struct device *dev)
disk_replace_part_tbl(disk, NULL);
+ if (disk->queue)
+ blk_put_queue(disk->queue);
struct class block_class = {