Re: [dm-devel] [PATCH V15 00/18] block: support multi-page bvec

Ming Lei
2019-02-20T01:17:51Z

On Tue, Feb 19, 2019 at 08:28:19AM -0800, Bart Van Assche wrote:
> On Sun, 2019-02-17 at 21:11 +0800, Ming Lei wrote:
> > The following patch should fix this issue:
> >
> >
> > diff --git a/block/blk-merge.c b/block/blk-merge.c
> > index bed065904677..066b66430523 100644
> > --- a/block/blk-merge.c
> > +++ b/block/blk-merge.c
> > @@ -363,13 +363,15 @@ static unsigned int __blk_recalc_rq_segments(struct request_queue *q,
> > struct bio_vec bv, bvprv = { NULL };
> > int prev = 0;
> > unsigned int seg_size, nr_phys_segs;
> > - unsigned front_seg_size = bio->bi_seg_front_size;
> > + unsigned front_seg_size;
> > struct bio *fbio, *bbio;
> > struct bvec_iter iter;
> >
> > if (!bio)
> > return 0;
> >
> > + front_seg_size = bio->bi_seg_front_size;
> > +
> > switch (bio_op(bio)) {
> > case REQ_OP_DISCARD:
> > case REQ_OP_SECURE_ERASE:
>
> Hi Ming,
>
> With this patch applied test nvmeof-mp/002 fails as follows:
>
> [ 694.700400] kernel BUG at lib/sg_pool.c:103!
> [ 694.705932] invalid opcode: 0000 [#1] PREEMPT SMP KASAN
> [ 694.708297] CPU: 2 PID: 349 Comm: kworker/2:1H Tainted: G B 5.0.0-rc6-dbg+ #2
> [ 694.711730] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1 04/01/2014
> [ 694.715113] Workqueue: kblockd blk_mq_run_work_fn
> [ 694.716894] RIP: 0010:sg_alloc_table_chained+0xe5/0xf0
> [ 694.758222] Call Trace:
> [ 694.759645] nvme_rdma_queue_rq+0x2aa/0xcc0 [nvme_rdma]
> [ 694.764915] blk_mq_try_issue_directly+0x2a5/0x4b0
> [ 694.771779] blk_insert_cloned_request+0x11e/0x1c0
> [ 694.778417] dm_mq_queue_rq+0x3d1/0x770
> [ 694.793400] blk_mq_dispatch_rq_list+0x5fc/0xb10
> [ 694.798386] blk_mq_sched_dispatch_requests+0x2f7/0x300
> [ 694.803180] __blk_mq_run_hw_queue+0xd6/0x180
> [ 694.808933] blk_mq_run_work_fn+0x27/0x30
> [ 694.810315] process_one_work+0x4f1/0xa40
> [ 694.813178] worker_thread+0x67/0x5b0
> [ 694.814487] kthread+0x1cf/0x1f0
> [ 694.819134] ret_from_fork+0x24/0x30
>
> The code in sg_pool.c that triggers the BUG() statement is as follows:
>
> int sg_alloc_table_chained(struct sg_table *table, int nents,
> struct scatterlist *first_chunk)
> {
> int ret;
>
> BUG_ON(!nents);
> [ ... ]
>
> Bart.

I can reproduce this issue("kernel BUG at lib/sg_pool.c:103") without mp-bvec patches,
so looks it isn't the fault of this patchset.

Thanks,
Ming