md/raid5: Before freeing old multi-thread worker, it should flush them.
When changing group_thread_cnt from sysfs entry, the kernel can oops.
The kernel messages are:
[ 740.961389] BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
[ 740.961444] IP: [<ffffffff81062570>] process_one_work+0x30/0x500
[ 740.961476] PGD b9013067 PUD b651e067 PMD 0
[ 740.961503] Oops: 0000 [#1] SMP
[ 740.961525] Modules linked in: netconsole e1000e ptp pps_core
[ 740.961577] CPU: 0 PID: 3683 Comm: kworker/u8:5 Not tainted 3.12.0+ #23
[ 740.961602] Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./To be filled by O.E.M., BIOS 080015 11/09/2011
[ 740.961646] task: ffff88013abe0000 ti: ffff88013a246000 task.ti: ffff88013a246000
[ 740.961673] RIP: 0010:[<ffffffff81062570>] [<ffffffff81062570>] process_one_work+0x30/0x500
[ 740.961708] RSP: 0018:ffff88013a247e08 EFLAGS: 00010086
[ 740.961730] RAX: ffff8800b912b400 RBX: ffff88013a61e680 RCX: ffff8800b912b400
[ 740.961757] RDX: ffff8800b912b600 RSI: ffff8800b912b600 RDI: ffff88013a61e680
[ 740.961782] RBP: ffff88013a247e48 R08: ffff88013a246000 R09: 000000000002c09d
[ 740.961808] R10: 000000000000010f R11: 0000000000000000 R12: ffff88013b00cc00
[ 740.961833] R13: 0000000000000000 R14: ffff88013b00cf80 R15: ffff88013a61e6b0
[ 740.961861] FS: 0000000000000000(0000) GS:ffff88013fc00000(0000) knlGS:0000000000000000
[ 740.961893] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[ 740.962001] CR2: 00000000000000b8 CR3: 00000000b24fe000 CR4: 00000000000407f0
[ 740.962001] Stack:
[ 740.962001] 0000000000000008 ffff8800b912b600 ffff88013b00cc00 ffff88013a61e680
[ 740.962001] ffff88013b00cc00 ffff88013b00cc18 ffff88013b00cf80 ffff88013a61e6b0
[ 740.962001] ffff88013a247eb8 ffffffff810639c6 0000000000012a80 ffff88013a247fd8
[ 740.962001] Call Trace:
[ 740.962001] [<ffffffff810639c6>] worker_thread+0x206/0x3f0
[ 740.962001] [<ffffffff810637c0>] ? manage_workers+0x2c0/0x2c0
[ 740.962001] [<ffffffff81069656>] kthread+0xc6/0xd0
[ 740.962001] [<ffffffff81069590>] ? kthread_freezable_should_stop+0x70/0x70
[ 740.962001] [<ffffffff81722ffc>] ret_from_fork+0x7c/0xb0
[ 740.962001] [<ffffffff81069590>] ? kthread_freezable_should_stop+0x70/0x70
[ 740.962001] Code: 89 e5 41 57 41 56 41 55 45 31 ed 41 54 53 48 89 fb 48 83 ec 18 48 8b 06 4c 8b 67 48 48 89 c1 30 c9 a8 04 4c 0f 45 e9 80 7f 58 00 <49> 8b 45 08 44 8b b0 00 01 00 00 78 0c 41 f6 44 24 10 04 0f 84
[ 740.962001] RIP [<ffffffff81062570>] process_one_work+0x30/0x500
[ 740.962001] RSP <ffff88013a247e08>
[ 740.962001] CR2: 0000000000000008
[ 740.962001] ---[ end trace 39181460000748de ]---
[ 740.962001] Kernel panic - not syncing: Fatal exception
This can happen if there are some stripes left, fewer than MAX_STRIPE_BATCH.
A worker is queued to handle them.
But before calling raid5_do_work, raid5d handles those
stripes making conf->active_stripe = 0.
So mddev_suspend() can return.
We might then free old worker resources before the queued
raid5_do_work() handled them. When it runs, it crashes.
raid5d() raid5_store_group_thread_cnt()
queue_work mddev_suspend()
handle_strips
active_stripe=0
free(old worker resources)
process_one_work
raid5_do_work
To avoid this, we should only flush the worker resources before freeing them.
This fixes a bug introduced in 3.12 so is suitable for the 3.12.x
stable series.
Cc: stable@vger.kernel.org (3.12)
Fixes: b721420e8719131896b009b11edbbd27
Signed-off-by: Jianpeng Ma <majianpeng@gmail.com>
Signed-off-by: NeilBrown <neilb@suse.de>
Reviewed-by: Shaohua Li <shli@kernel.org>
1 file changed
