On 02/10/2017 08:40 PM, Ming Lei wrote: > Inside set_status, transfer need to setup again, so > we have to drain IO before the transition, otherwise > oops may be triggered like the following: > > divide error: 0000 [#1] SMP KASAN > CPU: 0 PID: 2935 Comm: loop7 Not tainted 4.10.0-rc7+ #213 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs > 01/01/2011 > task: ffff88006ba1e840 task.stack: ffff880067338000 > RIP: 0010:transfer_xor+0x1d1/0x440 drivers/block/loop.c:110 > RSP: 0018:ffff88006733f108 EFLAGS: 00010246 > RAX: 0000000000000000 RBX: ffff8800688d7000 RCX: 0000000000000059 > RDX: 0000000000000000 RSI: 1ffff1000d743f43 RDI: ffff880068891c08 > RBP: ffff88006733f160 R08: ffff8800688d7001 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: ffff8800688d7000 > R13: ffff880067b7d000 R14: dffffc0000000000 R15: 0000000000000000 > FS: 0000000000000000(0000) GS:ffff88006d000000(0000) > knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00000000006c17e0 CR3: 0000000066e3b000 CR4: 00000000001406f0 > Call Trace: > lo_do_transfer drivers/block/loop.c:251 [inline] > lo_read_transfer drivers/block/loop.c:392 [inline] > do_req_filebacked drivers/block/loop.c:541 [inline] > loop_handle_cmd drivers/block/loop.c:1677 [inline] > loop_queue_work+0xda0/0x49b0 drivers/block/loop.c:1689 > kthread_worker_fn+0x4c3/0xa30 kernel/kthread.c:630 > kthread+0x326/0x3f0 kernel/kthread.c:227 > ret_from_fork+0x31/0x40 arch/x86/entry/entry_64.S:430 > Code: 03 83 e2 07 41 29 df 42 0f b6 04 30 4d 8d 44 24 01 38 d0 7f 08 > 84 c0 0f 85 62 02 00 00 44 89 f8 41 0f b6 48 ff 25 ff 01 00 00 99 <f7> > 7d c8 48 63 d2 48 03 55 d0 48 89 d0 48 89 d7 48 c1 e8 03 83 > RIP: transfer_xor+0x1d1/0x440 drivers/block/loop.c:110 RSP: > ffff88006733f108 > ---[ end trace 0166f7bd3b0c0933 ]--- Thanks Ming, added for 4.11. -- Jens Axboe
