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* [PATCH V2] raid1: ensure write behind bio has less than BIO_MAX_VECS sectors
@ 2021-08-18  7:37 Guoqing Jiang
  2021-08-18  7:57 ` Guoqing Jiang
                   ` (3 more replies)
  0 siblings, 4 replies; 9+ messages in thread
From: Guoqing Jiang @ 2021-08-18  7:37 UTC (permalink / raw)
  To: axboe; +Cc: linux-block, linux-raid

From: Guoqing Jiang <jiangguoqing@kylinos.cn>

We can't split write behind bio with more than BIO_MAX_VECS sectors,
otherwise the below call trace was triggered because we could allocate
oversized write behind bio later.

[ 8.097936] bvec_alloc+0x90/0xc0
[ 8.098934] bio_alloc_bioset+0x1b3/0x260
[ 8.099959] raid1_make_request+0x9ce/0xc50 [raid1]
[ 8.100988] ? __bio_clone_fast+0xa8/0xe0
[ 8.102008] md_handle_request+0x158/0x1d0 [md_mod]
[ 8.103050] md_submit_bio+0xcd/0x110 [md_mod]
[ 8.104084] submit_bio_noacct+0x139/0x530
[ 8.105127] submit_bio+0x78/0x1d0
[ 8.106163] ext4_io_submit+0x48/0x60 [ext4]
[ 8.107242] ext4_writepages+0x652/0x1170 [ext4]
[ 8.108300] ? do_writepages+0x41/0x100
[ 8.109338] ? __ext4_mark_inode_dirty+0x240/0x240 [ext4]
[ 8.110406] do_writepages+0x41/0x100
[ 8.111450] __filemap_fdatawrite_range+0xc5/0x100
[ 8.112513] file_write_and_wait_range+0x61/0xb0
[ 8.113564] ext4_sync_file+0x73/0x370 [ext4]
[ 8.114607] __x64_sys_fsync+0x33/0x60
[ 8.115635] do_syscall_64+0x33/0x40
[ 8.116670] entry_SYSCALL_64_after_hwframe+0x44/0xae

Thanks for the comment from Christoph.

[1]. https://bugs.archlinux.org/task/70992

Cc: Song Liu <song@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Reported-by: Jens Stutte <jens@chianterastutte.eu>
Tested-by: Jens Stutte <jens@chianterastutte.eu>
Signed-off-by: Guoqing Jiang <jiangguoqing@kylinos.cn>
---
Hi Jens,

Could you consider apply this to block tree? Since it depends
on commit 018eca456c4b4dca56aaf1ec27f309c74d0fe246 in block
tree for-next branch, otherwise lkp would complain about compile
issue again.

Thanks,
Guoqing

V2 change:
1. add checking for write-behind case and relevant comments from Christoph.

 drivers/md/raid1.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
index 3c44c4bb40fc..e8c8e6bb0439 100644
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -1329,6 +1329,7 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio,
 	struct raid1_plug_cb *plug = NULL;
 	int first_clone;
 	int max_sectors;
+	bool write_behind = false;
 
 	if (mddev_is_clustered(mddev) &&
 	     md_cluster_ops->area_resyncing(mddev, WRITE,
@@ -1381,6 +1382,10 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio,
 	max_sectors = r1_bio->sectors;
 	for (i = 0;  i < disks; i++) {
 		struct md_rdev *rdev = rcu_dereference(conf->mirrors[i].rdev);
+
+		if (test_bit(WriteMostly, &mirror->rdev->flags))
+			write_behind = true;
+
 		if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) {
 			atomic_inc(&rdev->nr_pending);
 			blocked_rdev = rdev;
@@ -1454,6 +1459,14 @@ static void raid1_write_request(struct mddev *mddev, struct bio *bio,
 		goto retry_write;
 	}
 
+	/*
+	 * When using a bitmap, we may call alloc_behind_master_bio below.
+	 * alloc_behind_master_bio allocates a copy of the data payload a page
+	 * at a time and thus needs a new bio that can fit the whole payload
+	 * this bio in page sized chunks.
+	 */
+	if (write_behind && bitmap)
+		max_sectors = min_t(int, max_sectors, BIO_MAX_VECS * PAGE_SECTORS);
 	if (max_sectors < bio_sectors(bio)) {
 		struct bio *split = bio_split(bio, max_sectors,
 					      GFP_NOIO, &conf->bio_split);
-- 
2.25.1


^ permalink raw reply related	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2021-08-23  6:51 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-08-18  7:37 [PATCH V2] raid1: ensure write behind bio has less than BIO_MAX_VECS sectors Guoqing Jiang
2021-08-18  7:57 ` Guoqing Jiang
2021-08-18 11:03 ` kernel test robot
2021-08-18 11:03   ` kernel test robot
2021-08-18 12:02 ` kernel test robot
2021-08-18 12:02   ` kernel test robot
2021-08-19  8:55 ` Christoph Hellwig
2021-08-20  8:19   ` Guoqing Jiang
2021-08-23  6:50     ` Christoph Hellwig

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