@@ -2251,6 +2251,13 @@ static void dm_init_md_queue(struct mapped_device *md)
* This queue is new, so no concurrency on the queue_flags.
*/
queue_flag_clear_unlocked(QUEUE_FLAG_STACKABLE, md->queue);
+
+ /*
+ * Initialize data that will only be used by a non-blk-mq DM queue
+ * - must do so here (in alloc_dev callchain) before queue is used
+ */
+ md->queue->queuedata = md;
+ md->queue->backing_dev_info.congested_data = md;
}
static void dm_init_old_md_queue(struct mapped_device *md)
@@ -2261,10 +2268,7 @@ static void dm_init_old_md_queue(struct mapped_device *md)
/*
* Initialize aspects of queue that aren't relevant for blk-mq
*/
- md->queue->queuedata = md;
md->queue->backing_dev_info.congested_fn = dm_any_congested;
- md->queue->backing_dev_info.congested_data = md;
-
blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY);
}
This is a note to let you know that I have just added a patch titled dm: initialize non-blk-mq queue data before queue is used to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue This patch is scheduled to be released in version 4.2.8-ckt1. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 4.2.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ------ From a16480324d29aeb4b5cefe3837c92e4dada07c96 Mon Sep 17 00:00:00 2001 From: Mikulas Patocka <mpatocka@redhat.com> Date: Tue, 27 Oct 2015 19:06:55 -0400 Subject: dm: initialize non-blk-mq queue data before queue is used commit ad5f498f610fa3fd8bd265139098bc1405cd2783 upstream. Commit bfebd1cdb497a57757c83f5fbf1a29931591e2a4 ("dm: add full blk-mq support to request-based DM") moves the initialization of the fields backing_dev_info.congested_fn, backing_dev_info.congested_data and queuedata from the function dm_init_md_queue (that is called when the device is created) to dm_init_old_md_queue (that is called after the device type is determined). There is no locking when accessing these variables, thus it is possible for other parts of the kernel to briefly see this data in a transient state (e.g. queue->backing_dev_info.congested_fn initialized and md->queue->backing_dev_info.congested_data uninitialized, resulting in passing an incorrect parameter to the function dm_any_congested). This queue data is left initialized for blk-mq devices even though they that don't use it. Fixes: bfebd1cdb497 ("dm: add full blk-mq support to request-based DM") Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- drivers/md/dm.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) -- 1.9.1