On Tue, Oct 11, 2016 at 11:54:09AM -0400, Chris Mason wrote:
>
>
> On 10/11/2016 10:45 AM, Dave Jones wrote:
> > This is from Linus' current tree, with Al's iovec fixups on top.
> >
> > ------------[ cut here ]------------
> > WARNING: CPU: 1 PID: 3673 at lib/list_debug.c:33 __list_add+0x89/0xb0
> > list_add corruption. prev->next should be next (ffffe8ffff806648), but was
> > ffffc9000067fcd8. (prev=ffff880503878b80).
> > CPU: 1 PID: 3673 Comm: trinity-c0 Not tainted 4.8.0-think+ #13
> > ffffc90000d87458 ffffffff8d32007c ffffc90000d874a8 0000000000000000
> > ffffc90000d87498 ffffffff8d07a6c1 0000002100000246 ffff88050388e880
> > ffff880503878b80 ffffe8ffff806648 ffffe8ffffc06600 ffff880502808008
> > Call Trace:
> > [<ffffffff8d32007c>] dump_stack+0x4f/0x73
> > [<ffffffff8d07a6c1>] __warn+0xc1/0xe0
> > [<ffffffff8d07a73a>] warn_slowpath_fmt+0x5a/0x80
> > [<ffffffff8d33e689>] __list_add+0x89/0xb0
> > [<ffffffff8d30a1c8>] blk_sq_make_request+0x2f8/0x350
>
> /*
>
> * A task plug currently exists. Since this is completely lockless,
>
> * utilize that to temporarily store requests until the task is
>
> * either done or scheduled away.
>
> */
>
> plug = current->plug;
>
> if (plug) {
>
> blk_mq_bio_to_request(rq, bio);
>
> if (!request_count)
>
> trace_block_plug(q);
>
>
>
> blk_mq_put_ctx(data.ctx);
>
>
>
> if (request_count >= BLK_MAX_REQUEST_COUNT) {
>
> blk_flush_plug_list(plug, false);
>
> trace_block_plug(q);
>
> }
>
>
>
> list_add_tail(&rq->queuelist, &plug->mq_list);
>
> ^^^^^^^^^^^^^^^^^^^^^^
>
> Dave, is this where we're crashing? This seems strange.
According to objdump -S ..
ffffffff8130a1b7: 48 8b 70 50 mov 0x50(%rax),%rsi
list_add_tail(&rq->queuelist, &ctx->rq_list);
ffffffff8130a1bb: 48 8d 50 48 lea 0x48(%rax),%rdx
ffffffff8130a1bf: 48 89 45 a8 mov %rax,-0x58(%rbp)
ffffffff8130a1c3: e8 38 44 03 00 callq ffffffff8133e600
<__list_add>
blk_mq_hctx_mark_pending(hctx, ctx);
ffffffff8130a1c8: 48 8b 45 a8 mov -0x58(%rbp),%rax
ffffffff8130a1cc: 4c 89 ff mov %r15,%rdi
That looks like the list_add_tail from __blk_mq_insert_req_list
Dave
