Check pers->hot_remove_disk instead of pers->hot_add_disk in slot_store() during disk removal. The linear personality only has ->hot_add_disk and no ->hot_remove_disk, so that removing disk in the array resulted to following kernel bug: $ sudo mdadm --create /dev/md0 --level=linear --raid-devices=4 /dev/loop[0-3] $ echo none | sudo tee /sys/block/md0/md/dev-loop2/slot BUG: unable to handle kernel NULL pointer dereference at (null) IP: [< (null)>] (null) PGD c9f5d067 PUD 8575a067 PMD 0 Oops: 0010 [#1] SMP CPU 2 Modules linked in: linear loop bridge stp llc kvm_intel kvm asus_atk0110 sr_mod cdrom sg Pid: 10450, comm: tee Not tainted 3.0.0-rc1-leonard+ #173 System manufacturer System Product Name/P5G41TD-M PRO RIP: 0010:[<0000000000000000>] [< (null)>] (null) RSP: 0018:ffff880085757df0 EFLAGS: 00010282 RAX: ffffffffa00168e0 RBX: ffff8800d1431800 RCX: 000000000000006e RDX: 0000000000000001 RSI: 0000000000000002 RDI: ffff88008543c000 RBP: ffff880085757e48 R08: 0000000000000002 R09: 000000000000000a R10: 0000000000000000 R11: ffff88008543c2e0 R12: 00000000ffffffff R13: ffff8800b4641000 R14: 0000000000000005 R15: 0000000000000000 FS: 00007fe8c9e05700(0000) GS:ffff88011fa00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000000 CR3: 00000000b4502000 CR4: 00000000000406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process tee (pid: 10450, threadinfo ffff880085756000, task ffff8800c9f08000) Stack: ffffffff8138496a ffff8800b4641000 ffff88008543c268 0000000000000000 ffff8800b4641000 ffff88008543c000 ffff8800d1431868 ffffffff81a78a90 ffff8800b4641000 ffff88008543c000 ffff8800d1431800 ffff880085757e98 Call Trace: [<ffffffff8138496a>] ? slot_store+0xaa/0x265 [<ffffffff81384bae>] rdev_attr_store+0x89/0xa8 [<ffffffff8115a96a>] sysfs_write_file+0x108/0x144 [<ffffffff81106b87>] vfs_write+0xb1/0x10d [<ffffffff8106e6c0>] ? trace_hardirqs_on_caller+0x111/0x135 [<ffffffff81106cac>] sys_write+0x4d/0x77 [<ffffffff814fe702>] system_call_fastpath+0x16/0x1b Code: Bad RIP value. RIP [< (null)>] (null) RSP <ffff880085757df0> CR2: 0000000000000000 ---[ end trace ba5fc64319a826fb ]--- Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxx> Cc: stable@xxxxxxxxxx --- drivers/md/md.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index f210e42a56ca..3db106b7b245 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -2461,7 +2461,7 @@ slot_store(mdk_rdev_t *rdev, const char *buf, size_t len) if (rdev->raid_disk == -1) return -EEXIST; /* personality does all needed checks */ - if (rdev->mddev->pers->hot_add_disk == NULL) + if (rdev->mddev->pers->hot_remove_disk == NULL) return -EINVAL; err = rdev->mddev->pers-> hot_remove_disk(rdev->mddev, rdev->raid_disk); -- 1.7.5.2 -- To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
