Whenever multipath_dtr is happening, we should prevent queueing any further path
activation work. There was a kernel panic where after pg_init_done() decrements
pg_init_in_progress to 0, wait_for_pg_init_completion call assumes there are no
more pending path management commands. But if pg_init_required is set by
pg_init_done call due to retriable mode_select errors , then process_queued_ios()
will again queue the path activation work. If free_multipath call has been
completed by the time activate_path work is called, kernel panic was seen on
accessing multipath members.
BUG: unable to handle kernel NULL pointer dereference at 0000000000000090
RIP: 0010:[<ffffffffa003db1b>] [<ffffffffa003db1b>] activate_path+0x1b/0x30 [dm_multipath]
[<ffffffff81090ac0>] worker_thread+0x170/0x2a0
[<ffffffff81096c80>] ? autoremove_wake_function+0x0/0x40
Signed-off-by: Shiva Krishna Merla<shivakrishna.merla@xxxxxxxxxx>
Reviewed-by: Krishnasamy Somasundaram<somasundaram.krishnasamy@xxxxxxxxxx>
Tested-by: Speagle Andy<Andy.Speagle@xxxxxxxxxx>
---
--- a/drivers/md/dm-mpath.c 2013-01-29 10:12:10.000000000 -0600
+++ b/drivers/md/dm-mpath.c 2013-10-29 21:02:03.267685017 -0500
@@ -73,6 +73,7 @@ struct multipath {
wait_queue_head_t pg_init_wait; /* Wait for pg_init completion */
+ unsigned dtr_in_progress; /* multipath destroy in progress */
unsigned pg_init_required; /* pg_init needs calling? */
unsigned pg_init_in_progress; /* Only one pg_init allowed at once */
unsigned pg_init_delay_retry; /* Delay pg_init retry? */
@@ -498,7 +499,8 @@ static void process_queued_ios(struct wo
(!pgpath && !m->queue_if_no_path))
must_queue = 0;
- if (m->pg_init_required && !m->pg_init_in_progress && pgpath)
+ if (m->pg_init_required && !m->pg_init_in_progress && pgpath &&
+ !m->dtr_in_progress)
__pg_init_all_paths(m);
spin_unlock_irqrestore(&m->lock, flags);
@@ -951,6 +953,11 @@ static void flush_multipath_work(struct
static void multipath_dtr(struct dm_target *ti)
{
struct multipath *m = ti->private;
+ unsigned long flags;
+
+ spin_lock_irqsave(&m->lock, flags);
+ m->dtr_in_progress = 1;
+ spin_unlock_irqrestore(&m->lock, flags);
flush_multipath_work(m);
free_multipath(m);
@@ -1164,7 +1171,7 @@ static int pg_init_limit_reached(struct
spin_lock_irqsave(&m->lock, flags);
- if (m->pg_init_count <= m->pg_init_retries)
+ if (m->pg_init_count <= m->pg_init_retries && !m->dtr_in_progress)
m->pg_init_required = 1;
else
limit_reached = 1;
--
--
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