On Mon, Aug 23, 2021 at 6:17 PM Guoqing Jiang <guoqing.jiang@xxxxxxxxx> wrote: > > From: Guoqing Jiang <jiangguoqing@xxxxxxxxxx> > > 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 > > Reported-by: Jens Stutte <jens@xxxxxxxxxxxxxxxxxx> > Tested-by: Jens Stutte <jens@xxxxxxxxxxxxxxxxxx> > Reviewed-by: Christoph Hellwig <hch@xxxxxx> > Signed-off-by: Guoqing Jiang <jiangguoqing@xxxxxxxxxx> I am confused. Which tree does this apply to? Thanks, Song > --- > V4 change: > 1. fix issue reported by lkp. > 2. add Reviewed-by tag. > > V3 change: > 1. add comment before test WriteMostly. > 2. reduce line length. > > V2 change: > 1. add checking for write-behind case and relevant comments from Christoph. > > drivers/md/raid1.c | 19 +++++++++++++++++++ > 1 file changed, 19 insertions(+) > > diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c > index 3c44c4bb40fc..ad51a60f1a93 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 +1382,15 @@ 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); > + > + /* > + * The write-behind io is only attempted on drives marked as > + * write-mostly, which means we could allocate write behind > + * bio later. > + */ > + if (rdev && test_bit(WriteMostly, &rdev->flags)) > + write_behind = true; > + > if (rdev && unlikely(test_bit(Blocked, &rdev->flags))) { > atomic_inc(&rdev->nr_pending); > blocked_rdev = rdev; > @@ -1454,6 +1464,15 @@ 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 >
