The patch titled
block: fix queue_lock NULL pointer derefence in blk_throtl_exit()
has been removed from the -mm tree. Its filename was
block-fix-queue_lock-null-pointer-derefence-in-blk_throtl_exit-v4.patch
This patch was dropped because it is obsolete
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: block: fix queue_lock NULL pointer derefence in blk_throtl_exit()
From: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
BUG: unable to handle kernel NULL pointer dereference at 0000000000000004
IP: [<ffffffff812479d4>] do_raw_spin_lock+0x14/0x122
Process modprobe (pid: 6189, threadinfo ffff88009a898000, task
ffff880154a88000)
Call Trace:
[<ffffffff81486788>] _raw_spin_lock_irq+0x4a/0x51
[<ffffffff8123404b>] ? blk_throtl_exit+0x3b/0xa0
[<ffffffff8105b120>] ? cancel_delayed_work_sync+0xd/0xf
[<ffffffff8123404b>] blk_throtl_exit+0x3b/0xa0
[<ffffffff81229bc8>] blk_release_queue+0x21/0x65
[<ffffffff8123bb06>] kobject_release+0x51/0x66
[<ffffffff8123bab5>] ? kobject_release+0x0/0x66
[<ffffffff8123ce1e>] kref_put+0x43/0x4d
[<ffffffff8123ba27>] kobject_put+0x47/0x4b
[<ffffffff8122717c>] blk_cleanup_queue+0x56/0x5b
[<ffffffffa01c3824>] loop_exit+0x68/0x844 [loop]
[<ffffffff8107cccc>] sys_delete_module+0x1e8/0x25b
[<ffffffff814864c9>] ? trace_hardirqs_on_thunk+0x3a/0x3f
[<ffffffff81002112>] system_call_fastpath+0x16/0x1b
because of an attempt to acquire NULL queue_lock. Added the same lines as
in blk_queue_make_request: 'fall back to embedded per-queue lock' - when
call blk_release_queue on allocated but never initialized queue.
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Cc: Jens Axboe <jaxboe@xxxxxxxxxxxx>
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
block/blk-sysfs.c | 6 ++++++
drivers/block/loop.c | 3 ---
2 files changed, 6 insertions(+), 3 deletions(-)
diff -puN block/blk-sysfs.c~block-fix-queue_lock-null-pointer-derefence-in-blk_throtl_exit-v4 block/blk-sysfs.c
--- a/block/blk-sysfs.c~block-fix-queue_lock-null-pointer-derefence-in-blk_throtl_exit-v4
+++ a/block/blk-sysfs.c
@@ -471,6 +471,12 @@ static void blk_release_queue(struct kob
blk_sync_queue(q);
+ /* It's possible that blk_release_queue will be called on allocated
+ * but never initialized queue. Fall back to our embedded per-queue
+ * locks in this case. */
+ if (!q->queue_lock)
+ q->queue_lock = &q->__queue_lock;
+
blk_throtl_exit(q);
if (rl->rq_pool)
diff -puN drivers/block/loop.c~block-fix-queue_lock-null-pointer-derefence-in-blk_throtl_exit-v4 drivers/block/loop.c
--- a/drivers/block/loop.c~block-fix-queue_lock-null-pointer-derefence-in-blk_throtl_exit-v4
+++ a/drivers/block/loop.c
@@ -1641,9 +1641,6 @@ out:
static void loop_free(struct loop_device *lo)
{
- if (!lo->lo_queue->queue_lock)
- lo->lo_queue->queue_lock = &lo->lo_queue->__queue_lock;
-
blk_cleanup_queue(lo->lo_queue);
put_disk(lo->lo_disk);
list_del(&lo->lo_list);
_
Patches currently in -mm which might be from sergey.senozhatsky@xxxxxxxxx are
mm-grab-rcu-read-lock-in-move_pages.patch
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