4.2.8-ckt7 -stable review patch. If anyone has any objections, please let me know.
---8<------------------------------------------------------------
From: Shaohua Li <shli@xxxxxx>
commit 27a353c026a879a1001e5eac4bda75b16262c44a upstream.
check_reshape() is called from raid5d thread. raid5d thread shouldn't
call mddev_suspend(), because mddev_suspend() waits for all IO finish
but IO is handled in raid5d thread, we could easily deadlock here.
This issue is introduced by
738a273 ("md/raid5: fix allocation of 'scribble' array.")
Reported-and-tested-by: Artur Paszkiewicz <artur.paszkiewicz@xxxxxxxxx>
Reviewed-by: NeilBrown <neilb@xxxxxxxx>
Signed-off-by: Shaohua Li <shli@xxxxxx>
Signed-off-by: Kamal Mostafa <kamal@xxxxxxxxxxxxx>
---
drivers/md/raid5.c | 18 ++++++++++++++++++
drivers/md/raid5.h | 2 ++
2 files changed, 20 insertions(+)
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index a6917f0..a55b6859 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -2091,6 +2091,14 @@ static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
unsigned long cpu;
int err = 0;
+ /*
+ * Never shrink. And mddev_suspend() could deadlock if this is called
+ * from raid5d. In that case, scribble_disks and scribble_sectors
+ * should equal to new_disks and new_sectors
+ */
+ if (conf->scribble_disks >= new_disks &&
+ conf->scribble_sectors >= new_sectors)
+ return 0;
mddev_suspend(conf->mddev);
get_online_cpus();
for_each_present_cpu(cpu) {
@@ -2112,6 +2120,10 @@ static int resize_chunks(struct r5conf *conf, int new_disks, int new_sectors)
}
put_online_cpus();
mddev_resume(conf->mddev);
+ if (!err) {
+ conf->scribble_disks = new_disks;
+ conf->scribble_sectors = new_sectors;
+ }
return err;
}
@@ -6379,6 +6391,12 @@ static int raid5_alloc_percpu(struct r5conf *conf)
}
put_online_cpus();
+ if (!err) {
+ conf->scribble_disks = max(conf->raid_disks,
+ conf->previous_raid_disks);
+ conf->scribble_sectors = max(conf->chunk_sectors,
+ conf->prev_chunk_sectors);
+ }
return err;
}
diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
index d051442..65ecd49 100644
--- a/drivers/md/raid5.h
+++ b/drivers/md/raid5.h
@@ -501,6 +501,8 @@ struct r5conf {
* conversions
*/
} __percpu *percpu;
+ int scribble_disks;
+ int scribble_sectors;
#ifdef CONFIG_HOTPLUG_CPU
struct notifier_block cpu_notify;
#endif
--
2.7.4
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