On Mon, Nov 7, 2022 at 6:17 AM Jiang Li <jiang.li1388@xxxxxxxxx> wrote:
>
> From: Jiang Li <jiang.li@xxxxxxxxxx>
>
> fail run raid1 array when we assemble array with the inactive disk only,
> but the mdx_raid1 thread were not stop, Even if the associated resources
> have been released. it will caused a NULL dereference when we do poweroff.
>
> This causes the following Oops:
> [ 287.587787] BUG: kernel NULL pointer dereference, address: 0000000000000070
> [ 287.594762] #PF: supervisor read access in kernel mode
> [ 287.599912] #PF: error_code(0x0000) - not-present page
> [ 287.605061] PGD 0 P4D 0
> [ 287.607612] Oops: 0000 [#1] SMP NOPTI
> [ 287.611287] CPU: 3 PID: 5265 Comm: md0_raid1 Tainted: G U 5.10.146 #0
> [ 287.619029] Hardware name: xxxxxxx/To be filled by O.E.M, BIOS 5.19 06/16/2022
> [ 287.626775] RIP: 0010:md_check_recovery+0x57/0x500 [md_mod]
> [ 287.632357] Code: fe 01 00 00 48 83 bb 10 03 00 00 00 74 08 48 89 ......
> [ 287.651118] RSP: 0018:ffffc90000433d78 EFLAGS: 00010202
> [ 287.656347] RAX: 0000000000000000 RBX: ffff888105986800 RCX: 0000000000000000
> [ 287.663491] RDX: ffffc90000433bb0 RSI: 00000000ffffefff RDI: ffff888105986800
> [ 287.670634] RBP: ffffc90000433da0 R08: 0000000000000000 R09: c0000000ffffefff
> [ 287.677771] R10: 0000000000000001 R11: ffffc90000433ba8 R12: ffff888105986800
> [ 287.684907] R13: 0000000000000000 R14: fffffffffffffe00 R15: ffff888100b6b500
> [ 287.692052] FS: 0000000000000000(0000) GS:ffff888277f80000(0000) knlGS:0000000000000000
> [ 287.700149] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 287.705897] CR2: 0000000000000070 CR3: 000000000320a000 CR4: 0000000000350ee0
> [ 287.713033] Call Trace:
> [ 287.715498] raid1d+0x6c/0xbbb [raid1]
> [ 287.719256] ? __schedule+0x1ff/0x760
> [ 287.722930] ? schedule+0x3b/0xb0
> [ 287.726260] ? schedule_timeout+0x1ed/0x290
> [ 287.730456] ? __switch_to+0x11f/0x400
> [ 287.734219] md_thread+0xe9/0x140 [md_mod]
> [ 287.738328] ? md_thread+0xe9/0x140 [md_mod]
> [ 287.742601] ? wait_woken+0x80/0x80
> [ 287.746097] ? md_register_thread+0xe0/0xe0 [md_mod]
> [ 287.751064] kthread+0x11a/0x140
> [ 287.754300] ? kthread_park+0x90/0x90
> [ 287.757974] ret_from_fork+0x1f/0x30
>
> In fact, when raid1 array run fail, we need to do
> md_unregister_thread() before raid1_free().
>
> Signed-off-by: Jiang Li <jiang.li@xxxxxxxxxx>
Applied to md-next. Thanks!
Song
> ---
> Hi,
> my full name is Jiang Li. Thanks!
>
> The following steps can be used to reproduce the problem:
> mdadm --create /dev/md0 --level=1 --raid-devices=2 /dev/sd[a-b]
> mdadm -A /dev/md0 /dev/sd[a-b]
> mkfs.ext4 /dev/md0
> mount /dev/md0 /mnt/md0
>
> mdadm -S /dev/md0
>
> mdadm -A /dev/md0 /dev/sda --run
> mount /dev/md0 /mnt/md0
> #Store a certain amount of data, so that the rebuilding will not be completed in a short time
> dd if=/dev/urandom of=/mnt/md0/test.db bs=1M count=40960
>
> mdadm --add /dev/md0 /dev/sdb
> sleep 1
> #when the array were rebuilding, we stop the array.
> umount /dev/md0
> mdadm -S /dev/md0
>
> #assemble array with the sdb only in --run insist mode:
> mdadm -A /dev/md0 /dev/sdb --run
>
> #md run fail with kernel message as follow:
> [ 850.593441] md: md0 stopped.
> [ 850.672071] md: pers->run() failed ...
> [ 850.686913] md: md0 stopped.
>
> #we can see the md0_raid1 thread were not stop:
> $ps -ef | grep raid1
> root 5672 2 0 Oct31 ? 00:00:04 [md0_raid1]
>
> #now, do poweroff can reproduce the problem.
>
> drivers/md/raid1.c | 1 +
> 1 file changed, 1 insertion(+)
>
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index 05d8438cfec8..58f705f42948 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -3159,6 +3159,7 @@ static int raid1_run(struct mddev *mddev)
> * RAID1 needs at least one disk in active
> */
> if (conf->raid_disks - mddev->degraded < 1) {
> + md_unregister_thread(&conf->thread);
> ret = -EINVAL;
> goto abort;
> }
> --
> 2.25.1
>
