diff options
| author | Yang Erkun <yangerkun@huawei.com> | 2025-07-31 19:45:30 +0800 |
|---|---|---|
| committer | Yu Kuai <yukuai3@huawei.com> | 2025-08-03 13:08:18 +0800 |
| commit | 13017b427118f4311471ee47df74872372ca8482 (patch) | |
| tree | da7f9a131a9785f7b852ba89dc99b9722ee6c9b7 | |
| parent | 178d1391c5ce0fc829f3e748058acab9bd9ca4f4 (diff) | |
md: make rdev_addable usable for rcu mode
Our testcase trigger panic:
BUG: kernel NULL pointer dereference, address: 00000000000000e0
...
Oops: Oops: 0000 [#1] SMP NOPTI
CPU: 2 UID: 0 PID: 85 Comm: kworker/2:1 Not tainted 6.16.0+ #94
PREEMPT(none)
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.16.1-2.fc37 04/01/2014
Workqueue: md_misc md_start_sync
RIP: 0010:rdev_addable+0x4d/0xf0
...
Call Trace:
<TASK>
md_start_sync+0x329/0x480
process_one_work+0x226/0x6d0
worker_thread+0x19e/0x340
kthread+0x10f/0x250
ret_from_fork+0x14d/0x180
ret_from_fork_asm+0x1a/0x30
</TASK>
Modules linked in: raid10
CR2: 00000000000000e0
---[ end trace 0000000000000000 ]---
RIP: 0010:rdev_addable+0x4d/0xf0
md_spares_need_change in md_start_sync will call rdev_addable which
protected by rcu_read_lock/rcu_read_unlock. This rcu context will help
protect rdev won't be released, but rdev->mddev will be set to NULL
before we call synchronize_rcu in md_kick_rdev_from_array. Fix this by
using READ_ONCE and check does rdev->mddev still alive.
Fixes: bc08041b32ab ("md: suspend array in md_start_sync() if array need reconfiguration")
Fixes: 570b9147deb6 ("md: use RCU lock to protect traversal in md_spares_need_change()")
Signed-off-by: Yang Erkun <yangerkun@huawei.com>
Link: https://lore.kernel.org/linux-raid/20250731114530.776670-1-yangerkun@huawei.com
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
| -rw-r--r-- | drivers/md/md.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c index 9c7ed23c45ad..ac85ec73a409 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -9427,6 +9427,12 @@ static bool rdev_is_spare(struct md_rdev *rdev) static bool rdev_addable(struct md_rdev *rdev) { + struct mddev *mddev; + + mddev = READ_ONCE(rdev->mddev); + if (!mddev) + return false; + /* rdev is already used, don't add it again. */ if (test_bit(Candidate, &rdev->flags) || rdev->raid_disk >= 0 || test_bit(Faulty, &rdev->flags)) @@ -9437,7 +9443,7 @@ static bool rdev_addable(struct md_rdev *rdev) return true; /* Allow to add if array is read-write. */ - if (md_is_rdwr(rdev->mddev)) + if (md_is_rdwr(mddev)) return true; /* |