6.5-stable review patch. If anyone has any objections, please let me know.
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From: Yu Kuai yukuai3@huawei.com
[ Upstream commit 99892147f028d711f9d40fefad4f33632593864c ]
Commit a1d767191096 ("md: use mddev->external to select holder in export_rdev()") fix the problem that 'claim_rdev' is used for blkdev_get_by_dev() while 'rdev' is used for blkdev_put().
However, if mddev->external is changed from 0 to 1, then 'rdev' is used for blkdev_get_by_dev() while 'claim_rdev' is used for blkdev_put(). And this problem can be reporduced reliably by following:
New file: mdadm/tests/23rdev-lifetime
devname=${dev0##*/} devt=`cat /sys/block/$devname/dev` pid="" runtime=2
clean_up_test() { pill -9 $pid echo clear > /sys/block/md0/md/array_state }
trap 'clean_up_test' EXIT
add_by_sysfs() { while true; do echo $devt > /sys/block/md0/md/new_dev done }
remove_by_sysfs(){ while true; do echo remove > /sys/block/md0/md/dev-${devname}/state done }
echo md0 > /sys/module/md_mod/parameters/new_array || die "create md0 failed"
add_by_sysfs & pid="$pid $!"
remove_by_sysfs & pid="$pid $!"
sleep $runtime exit 0
Test cmd:
./test --save-logs --logdir=/tmp/ --keep-going --dev=loop --tests=23rdev-lifetime
Test result:
------------[ cut here ]------------ WARNING: CPU: 0 PID: 960 at block/bdev.c:618 blkdev_put+0x27c/0x330 Modules linked in: multipath md_mod loop CPU: 0 PID: 960 Comm: test Not tainted 6.5.0-rc2-00121-g01e55c376936-dirty #50 RIP: 0010:blkdev_put+0x27c/0x330 Call Trace: <TASK> export_rdev.isra.23+0x50/0xa0 [md_mod] mddev_unlock+0x19d/0x300 [md_mod] rdev_attr_store+0xec/0x190 [md_mod] sysfs_kf_write+0x52/0x70 kernfs_fop_write_iter+0x19a/0x2a0 vfs_write+0x3b5/0x770 ksys_write+0x74/0x150 __x64_sys_write+0x22/0x30 do_syscall_64+0x40/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd
Fix the problem by recording if 'rdev' is used as holder.
Fixes: a1d767191096 ("md: use mddev->external to select holder in export_rdev()") Signed-off-by: Yu Kuai yukuai3@huawei.com Signed-off-by: Song Liu song@kernel.org Link: https://lore.kernel.org/r/20230825025532.1523008-3-yukuai1@huaweicloud.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/md/md.c | 15 ++++++++++++--- drivers/md/md.h | 3 +++ 2 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/drivers/md/md.c b/drivers/md/md.c index fba2809cd384a..06a8ccdb5135d 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -2452,7 +2452,8 @@ static void export_rdev(struct md_rdev *rdev, struct mddev *mddev) if (test_bit(AutoDetected, &rdev->flags)) md_autodetect_dev(rdev->bdev->bd_dev); #endif - blkdev_put(rdev->bdev, mddev->external ? &claim_rdev : rdev); + blkdev_put(rdev->bdev, + test_bit(Holder, &rdev->flags) ? rdev : &claim_rdev); rdev->bdev = NULL; kobject_put(&rdev->kobj); } @@ -3632,6 +3633,7 @@ EXPORT_SYMBOL_GPL(md_rdev_init); static struct md_rdev *md_import_device(dev_t newdev, int super_format, int super_minor) { struct md_rdev *rdev; + struct md_rdev *holder; sector_t size; int err;
@@ -3646,8 +3648,15 @@ static struct md_rdev *md_import_device(dev_t newdev, int super_format, int supe if (err) goto out_clear_rdev;
+ if (super_format == -2) { + holder = &claim_rdev; + } else { + holder = rdev; + set_bit(Holder, &rdev->flags); + } + rdev->bdev = blkdev_get_by_dev(newdev, BLK_OPEN_READ | BLK_OPEN_WRITE, - super_format == -2 ? &claim_rdev : rdev, NULL); + holder, NULL); if (IS_ERR(rdev->bdev)) { pr_warn("md: could not open device unknown-block(%u,%u).\n", MAJOR(newdev), MINOR(newdev)); @@ -3684,7 +3693,7 @@ static struct md_rdev *md_import_device(dev_t newdev, int super_format, int supe return rdev;
out_blkdev_put: - blkdev_put(rdev->bdev, super_format == -2 ? &claim_rdev : rdev); + blkdev_put(rdev->bdev, holder); out_clear_rdev: md_rdev_clear(rdev); out_free_rdev: diff --git a/drivers/md/md.h b/drivers/md/md.h index 1aef86bf3fc31..b0a0f5a5c7836 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -211,6 +211,9 @@ enum flag_bits { * check if there is collision between raid1 * serial bios. */ + Holder, /* rdev is used as holder while opening + * underlying disk exclusively. + */ };
static inline int is_badblock(struct md_rdev *rdev, sector_t s, int sectors,