On Wed, Oct 26, 2016 at 03:21:53PM -0700, Linus Torvalds wrote: > Could you try the attached patch? It adds a couple of sanity tests: > > - a number of tests to verify that 'rq->queuelist' isn't already on > some queue when it is added to a queue > > - one test to verify that rq->mq_ctx is the same ctx that we have locked. > > I may be completely full of shit, and this patch may be pure garbage > or "obviously will never trigger", but humor me. I gave it a shot too for shits & giggles. This falls out during boot.
[ 9.244030] EXT4-fs (sda4): mounted filesystem with ordered data mode. Opts: (null) [ 9.271391] ------------[ cut here ]------------ [ 9.278420] WARNING: CPU: 0 PID: 1 at block/blk-mq.c:1181 blk_sq_make_request+0x465/0x4a0 [ 9.285613] CPU: 0 PID: 1 Comm: init Not tainted 4.9.0-rc2-think+ #4 [ 9.300106] ffffc90000013848 [ 9.307353] ffffffff8130d27c [ 9.307420] 0000000000000000 [ 9.307456] 0000000000000000 [ 9.307494] ffffc90000013888 [ 9.314780] ffffffff81077a41 [ 9.314847] 0000049d00013898 [ 9.314884] 0000000000000001 [ 9.314922] 0000000000000002 [ 9.322213] ffffe8ffffc06600 [ 9.322280] ffffe8ffff606600 [ 9.322317] ffff8805015c2e80 [ 9.322355] Call Trace: [ 9.329689] [<ffffffff8130d27c>] dump_stack+0x4f/0x73 [ 9.337208] [<ffffffff81077a41>] __warn+0xc1/0xe0 [ 9.344730] [<ffffffff81077b18>] warn_slowpath_null+0x18/0x20 [ 9.352282] [<ffffffff812f7975>] blk_sq_make_request+0x465/0x4a0 [ 9.359816] [<ffffffff812eb44a>] ? generic_make_request+0xca/0x210 [ 9.367367] [<ffffffff812eb457>] generic_make_request+0xd7/0x210 [ 9.374931] [<ffffffff812eb5f9>] submit_bio+0x69/0x120 [ 9.382488] [<ffffffff812004ef>] ? submit_bh_wbc+0x16f/0x1e0 [ 9.390083] [<ffffffff812004ef>] submit_bh_wbc+0x16f/0x1e0 [ 9.397673] [<ffffffff81200bfe>] submit_bh+0xe/0x10 [ 9.405205] [<ffffffff81255eac>] __ext4_get_inode_loc+0x1ac/0x3d0 [ 9.412795] [<ffffffff81258f4b>] ext4_iget+0x6b/0xb70 [ 9.420366] [<ffffffff811d6018>] ? lookup_slow+0xf8/0x1f0 [ 9.427947] [<ffffffff81259a7a>] ext4_iget_normal+0x2a/0x30 [ 9.435541] [<ffffffff81264734>] ext4_lookup+0x114/0x230