From: Heinz Mauelshagen <heinzm@xxxxxxxxxx>
This patch avoids oopses caused by a callback racing
with the destrution of a mapping.
Signed-off-by: Heinz Mauelshagen <heinzm@xxxxxxxxxx>
Tested-by: Heinz Mauelshagen <heinzm@xxxxxxxxxx>
---
drivers/md/dm-raid.c | 18 ++++++++++++++++++
1 file changed, 18 insertions(+)
diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 88e4c7f..fc4bc83 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -1614,6 +1614,17 @@ static void raid_presuspend(struct dm_target *ti)
{
struct raid_set *rs = ti->private;
+ /*
+ * Address a teardown race when calling
+ * raid_(pre|post)suspend followed by raid_dtr:
+ *
+ * MD's call chain md_stop_writes()->md_reap_sync_thread()
+ * causes work to be queued on the md_misc_wq queue
+ * not flushing it, hence the callback can occur after
+ * a potential destruction of the raid set causing an oops.
+ */
+ rs->md.event_work.func = NULL;
+
md_stop_writes(&rs->md);
}
@@ -1684,6 +1695,13 @@ static void raid_resume(struct dm_target *ti)
{
struct raid_set *rs = ti->private;
+ /*
+ * See "Address a teardown race" in raid_presuspend()
+ *
+ * Reenable the worker function.
+ */
+ rs->md.event_work.func = do_table_event;
+
set_bit(MD_CHANGE_DEVS, &rs->md.flags);
if (!rs->bitmap_loaded) {
bitmap_load(&rs->md);
--
2.1.0
--
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