- rel 2; fix raid10 lockup on resync/raid checkauto/th/kernel-nopae-4.20.0-2auto/th/kernel-4.20.0-2

1 files changed, 124 insertions, 0 deletions

diff --git a/kernel-small_fixes.patch b/kernel-small_fixes.patch
index b97c7aa..63bd479 100644
--- a/kernel-small_fixes.patch
+++ b/kernel-small_fixes.patch
@@ -38,3 +38,127 @@ index 584cf2d..aea3bc2 100644
  
  	/* version 5 superblocks support inode version counters. */
  	if (XFS_SB_VERSION_NUM(&mp->m_sb) == XFS_SB_VERSION_5)
+From e820d55cb99dd93ac2dc949cf486bb187e5cd70d Mon Sep 17 00:00:00 2001
+From: Guoqing Jiang <gqjiang@suse.com>
+Date: Wed, 19 Dec 2018 14:19:25 +0800
+Subject: md: fix raid10 hang issue caused by barrier
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+When both regular IO and resync IO happen at the same time,
+and if we also need to split regular. Then we can see tasks
+hang due to barrier.
+
+1. resync thread
+[ 1463.757205] INFO: task md1_resync:5215 blocked for more than 480 seconds.
+[ 1463.757207]       Not tainted 4.19.5-1-default #1
+[ 1463.757209] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
+[ 1463.757212] md1_resync      D    0  5215      2 0x80000000
+[ 1463.757216] Call Trace:
+[ 1463.757223]  ? __schedule+0x29a/0x880
+[ 1463.757231]  ? raise_barrier+0x8d/0x140 [raid10]
+[ 1463.757236]  schedule+0x78/0x110
+[ 1463.757243]  raise_barrier+0x8d/0x140 [raid10]
+[ 1463.757248]  ? wait_woken+0x80/0x80
+[ 1463.757257]  raid10_sync_request+0x1f6/0x1e30 [raid10]
+[ 1463.757265]  ? _raw_spin_unlock_irq+0x22/0x40
+[ 1463.757284]  ? is_mddev_idle+0x125/0x137 [md_mod]
+[ 1463.757302]  md_do_sync.cold.78+0x404/0x969 [md_mod]
+[ 1463.757311]  ? wait_woken+0x80/0x80
+[ 1463.757336]  ? md_rdev_init+0xb0/0xb0 [md_mod]
+[ 1463.757351]  md_thread+0xe9/0x140 [md_mod]
+[ 1463.757358]  ? _raw_spin_unlock_irqrestore+0x2e/0x60
+[ 1463.757364]  ? __kthread_parkme+0x4c/0x70
+[ 1463.757369]  kthread+0x112/0x130
+[ 1463.757374]  ? kthread_create_worker_on_cpu+0x40/0x40
+[ 1463.757380]  ret_from_fork+0x3a/0x50
+
+2. regular IO
+[ 1463.760679] INFO: task kworker/0:8:5367 blocked for more than 480 seconds.
+[ 1463.760683]       Not tainted 4.19.5-1-default #1
+[ 1463.760684] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
+[ 1463.760687] kworker/0:8     D    0  5367      2 0x80000000
+[ 1463.760718] Workqueue: md submit_flushes [md_mod]
+[ 1463.760721] Call Trace:
+[ 1463.760731]  ? __schedule+0x29a/0x880
+[ 1463.760741]  ? wait_barrier+0xdd/0x170 [raid10]
+[ 1463.760746]  schedule+0x78/0x110
+[ 1463.760753]  wait_barrier+0xdd/0x170 [raid10]
+[ 1463.760761]  ? wait_woken+0x80/0x80
+[ 1463.760768]  raid10_write_request+0xf2/0x900 [raid10]
+[ 1463.760774]  ? wait_woken+0x80/0x80
+[ 1463.760778]  ? mempool_alloc+0x55/0x160
+[ 1463.760795]  ? md_write_start+0xa9/0x270 [md_mod]
+[ 1463.760801]  ? try_to_wake_up+0x44/0x470
+[ 1463.760810]  raid10_make_request+0xc1/0x120 [raid10]
+[ 1463.760816]  ? wait_woken+0x80/0x80
+[ 1463.760831]  md_handle_request+0x121/0x190 [md_mod]
+[ 1463.760851]  md_make_request+0x78/0x190 [md_mod]
+[ 1463.760860]  generic_make_request+0x1c6/0x470
+[ 1463.760870]  raid10_write_request+0x77a/0x900 [raid10]
+[ 1463.760875]  ? wait_woken+0x80/0x80
+[ 1463.760879]  ? mempool_alloc+0x55/0x160
+[ 1463.760895]  ? md_write_start+0xa9/0x270 [md_mod]
+[ 1463.760904]  raid10_make_request+0xc1/0x120 [raid10]
+[ 1463.760910]  ? wait_woken+0x80/0x80
+[ 1463.760926]  md_handle_request+0x121/0x190 [md_mod]
+[ 1463.760931]  ? _raw_spin_unlock_irq+0x22/0x40
+[ 1463.760936]  ? finish_task_switch+0x74/0x260
+[ 1463.760954]  submit_flushes+0x21/0x40 [md_mod]
+
+So resync io is waiting for regular write io to complete to
+decrease nr_pending (conf->barrier++ is called before waiting).
+The regular write io splits another bio after call wait_barrier
+which call nr_pending++, then the splitted bio would continue
+with raid10_write_request -> wait_barrier, so the splitted bio
+has to wait for barrier to be zero, then deadlock happens as
+follows.
+
+	resync io		regular io
+
+	raise_barrier
+				wait_barrier
+				generic_make_request
+				wait_barrier
+
+To resolve the issue, we need to call allow_barrier to decrease
+nr_pending before generic_make_request since regular IO is not
+issued to underlying devices, and wait_barrier is called again
+to ensure no internal IO happening.
+
+Fixes: fc9977dd069e ("md/raid10: simplify the splitting of requests.")
+Reported-and-tested-by: Siniša Bandin <sinisa@4net.rs>
+Signed-off-by: Guoqing Jiang <gqjiang@suse.com>
+Signed-off-by: Shaohua Li <shli@fb.com>
+---
+ drivers/md/raid10.c | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
+index 76c92e31afc0..abb5d382f64d 100644
+--- a/drivers/md/raid10.c
++++ b/drivers/md/raid10.c
+@@ -1209,7 +1209,9 @@ static void raid10_read_request(struct mddev *mddev, struct bio *bio,
+ 		struct bio *split = bio_split(bio, max_sectors,
+ 					      gfp, &conf->bio_split);
+ 		bio_chain(split, bio);
++		allow_barrier(conf);
+ 		generic_make_request(bio);
++		wait_barrier(conf);
+ 		bio = split;
+ 		r10_bio->master_bio = bio;
+ 		r10_bio->sectors = max_sectors;
+@@ -1492,7 +1494,9 @@ retry_write:
+ 		struct bio *split = bio_split(bio, r10_bio->sectors,
+ 					      GFP_NOIO, &conf->bio_split);
+ 		bio_chain(split, bio);
++		allow_barrier(conf);
+ 		generic_make_request(bio);
++		wait_barrier(conf);
+ 		bio = split;
+ 		r10_bio->master_bio = bio;
+ 	}
+-- 
+cgit 1.2-0.3.lf.el7
+