[dm-devel] bioset_exit poison from dm_destroy

[Jens Axboe]

On 5/31/22 1:49 PM, Mike Snitzer wrote:
> On Tue, May 31 2022 at  3:00P -0400,
> Jens Axboe <axboe at kernel.dk> wrote:
> 
>> On 5/31/22 12:58 PM, Mike Snitzer wrote:
>>> On Sun, May 29 2022 at  8:46P -0400,
>>> Jens Axboe <axboe at kernel.dk> wrote:
>>>
>>>> On 5/28/22 6:17 PM, Matthew Wilcox wrote:
>>>>> Not quite sure whose bug this is.  Current Linus head running xfstests
>>>>> against ext4 (probably not ext4's fault?)
>>>>>
>>>>> 01818 generic/250	run fstests generic/250 at 2022-05-28 23:48:09
>>>>> 01818 EXT4-fs (dm-0): mounted filesystem with ordered data mode. Quota mode: none.
>>>>> 01818 EXT4-fs (dm-0): unmounting filesystem.
>>>>> 01818 EXT4-fs (dm-0): mounted filesystem with ordered data mode. Quota mode: none.
>>>>> 01818 EXT4-fs (dm-0): unmounting filesystem.
>>>>> 01818 EXT4-fs (dm-0): mounted filesystem with ordered data mode. Quota mode: none.
>>>>> 01818 Buffer I/O error on dev dm-0, logical block 3670000, async page read
>>>>> 01818 EXT4-fs (dm-0): unmounting filesystem.
>>>>> 01818 EXT4-fs (dm-0): mounted filesystem with ordered data mode. Quota mode: none.
>>>>> 01818 EXT4-fs (dm-0): unmounting filesystem.
>>>>> 01818 general protection fault, probably for non-canonical address 0xdead000000000122: 0000 [#1] PREEMPT SMP NOPTI
>>>>> 01818 CPU: 0 PID: 1579117 Comm: dmsetup Kdump: loaded Not tainted 5.18.0-11049-g1dec3d7fd0c3-dirty #262
>>>>> 01818 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.15.0-1 04/01/2014
>>>>> 01818 RIP: 0010:__cpuhp_state_remove_instance+0xf0/0x1b0
>>>>> 01818 Code: a0 f8 d7 81 42 3b 1c 28 7f d9 4c 89 e1 31 d2 89 de 89 7d dc e8 01 fd ff ff 8b 7d dc eb c5 49 8b 04 24 49 8b 54 24 08 48 85 c0 <48> 89 02 74 04 48 89 50 08 48 b8 00 01 00 00 00 00 ad de 48 c7 c7
>>>>> 01818 RSP: 0018:ffff888101fcfc60 EFLAGS: 00010286
>>>>> 01818 RAX: dead000000000100 RBX: 0000000000000017 RCX: 0000000000000000
>>>>> 01818 RDX: dead000000000122 RSI: ffff8881233b0ae8 RDI: ffffffff81e3b080
>>>>> 01818 RBP: ffff888101fcfc88 R08: 0000000000000008 R09: 0000000000000003
>>>>> 01818 R10: 0000000000000000 R11: 00000000002dc6c0 R12: ffff8881233b0ae8
>>>>> 01818 R13: 0000000000000000 R14: ffffffff81e38f58 R15: ffff88817b5a3c00
>>>>> 01818 FS:  00007ff56daec280(0000) GS:ffff888275800000(0000) knlGS:0000000000000000
>>>>> 01818 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
>>>>> 01818 CR2: 00005591ad94f198 CR3: 000000017b5a0004 CR4: 0000000000770eb0
>>>>> 01818 PKRU: 55555554
>>>>> 01818 Call Trace:
>>>>> 01818  <TASK>
>>>>> 01818  ? kfree+0x66/0x250
>>>>> 01818  bioset_exit+0x32/0x210
>>>>> 01818  cleanup_mapped_device+0x34/0xf0
>>>>> 01818  __dm_destroy+0x149/0x1f0
>>>>> 01818  ? table_clear+0xc0/0xc0
>>>>> 01818  dm_destroy+0xe/0x10
>>>>> 01818  dev_remove+0xd9/0x120
>>>>> 01818  ctl_ioctl+0x1cb/0x420
>>>>> 01818  dm_ctl_ioctl+0x9/0x10
>>>>> 01818  __x64_sys_ioctl+0x89/0xb0
>>>>> 01818  do_syscall_64+0x35/0x80
>>>>> 01818  entry_SYSCALL_64_after_hwframe+0x46/0xb0
>>>>> 01818 RIP: 0033:0x7ff56de3b397
>>>>> 01818 Code: 3c 1c e8 1c ff ff ff 85 c0 79 87 49 c7 c4 ff ff ff ff 5b 5d 4c 89 e0 41 5c c3 66 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d a9 da 0d 00 f7 d8 64 89 01 48
>>>>> 01818 RSP: 002b:00007ffe55367ef8 EFLAGS: 00000206 ORIG_RAX: 0000000000000010
>>>>> 01818 RAX: ffffffffffffffda RBX: 00007ff56df31a8e RCX: 00007ff56de3b397
>>>>> 01818 RDX: 000055daad7cab30 RSI: 00000000c138fd04 RDI: 0000000000000003
>>>>> 01818 RBP: 00007ffe55367fb0 R08: 00007ff56df81558 R09: 00007ffe55367d60
>>>>> 01818 R10: 00007ff56df808a2 R11: 0000000000000206 R12: 00007ff56df808a2
>>>>> 01818 R13: 00007ff56df808a2 R14: 00007ff56df808a2 R15: 00007ff56df808a2
>>>>> 01818  </TASK>
>>>>> 01818 Modules linked in: crct10dif_generic crct10dif_common [last unloaded: crc_t10dif]
>>>>
>>>> I suspect dm is calling bioset_exit() multiple times? Which it probably
>>>> should not.
>>>>
>>>> The reset of bioset_exit() is resilient against this, so might be best
>>>> to include bio_alloc_cache_destroy() in that.
>>>>
>>>>
>>>> diff --git a/block/bio.c b/block/bio.c
>>>> index a3893d80dccc..be3937b84e68 100644
>>>> --- a/block/bio.c
>>>> +++ b/block/bio.c
>>>> @@ -722,6 +722,7 @@ static void bio_alloc_cache_destroy(struct bio_set *bs)
>>>>  		bio_alloc_cache_prune(cache, -1U);
>>>>  	}
>>>>  	free_percpu(bs->cache);
>>>> +	bs->cache = NULL;
>>>>  }
>>>>  
>>>>  /**
>>>
>>> Yes, we need the above to fix the crash.  Does it also make sense to
>>> add this?
>>>
>>> diff --git a/include/linux/bio.h b/include/linux/bio.h
>>> index 49eff01fb829..f410c78e9c0c 100644
>>> --- a/include/linux/bio.h
>>> +++ b/include/linux/bio.h
>>> @@ -681,7 +681,7 @@ struct bio_set {
>>>
>>>  static inline bool bioset_initialized(struct bio_set *bs)
>>>  {
>>> -	return bs->bio_slab != NULL;
>>> +	return (bs->bio_slab != NULL || bs->cache != NULL);
>>>  }
>>
>> Should not be possible to have valid bs->cache without bs->bio_slab?
> 
> Not quite following your question, but I sprinkled this extra check in
> purely because DM core uses bioset_initialized() to verify that the
> bioset is _not_ yet initialized.
> 
> But it really doesn't make sense to consider the bioset _fully_
> initialized if bs->bio_slab is NULL but bs->cache is NOT...

Honestly, I'd be way happier getting rid of bioset_initialized()!

> Anyway, really don't need this change but we do need your earlier
> patch to reset bs->cache to NULL.

Certainly, that patch will be going upstream in a day or two.

-- 
Jens Axboe