Re: [PATCH 1/4] block: add rq_flags to struct blk_mq_alloc_data

Guenter Roeck
2021-11-03T19:54:17Z

Hi,

On Tue, Oct 19, 2021 at 09:32:57AM -0600, Jens Axboe wrote:
> There's a hole here we can use, and it's faster to set this earlier
> rather than need to check q->elevator multiple times.
>
> Signed-off-by: Jens Axboe <axboe@kernel.dk>

This patch results in a warning backtrace with one of my qemu
boot tests.

[ 48.268501] ------------[ cut here ]------------
[ 48.268620] WARNING: CPU: 0 PID: 1 at block/blk-mq-sched.c:432 blk_mq_sched_insert_request+0x3e/0x150
[ 48.268771] Modules linked in:
[ 48.268973] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.15.0+ #1
[ 48.269198] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
[ 48.269419] RIP: 0010:blk_mq_sched_insert_request+0x3e/0x150
[ 48.269613] Code: ec 20 4c 8b 47 08 4c 8b 77 10 65 48 8b 04 25 28 00 00 00 48 89 44 24 18 48 8b 07 4c 8b 78 08 4d 85 ff 74 08 83 7f 20 ff 74 02 <0f> 0b f6 45 1c 10 0f 85 a6 00 00 00 0f b6 45 18 44 0f b6 e6 83 e8
[ 48.269851] RSP: 0018:ffff991500013a00 EFLAGS: 00000217
[ 48.269955] RAX: ffff88e4c36e8ce8 RBX: 0000000000000001 RCX: 0000000000000000
[ 48.270131] RDX: 0000000000000001 RSI: 0000000000000001 RDI: ffff88e4c369d340
[ 48.270232] RBP: ffff88e4c369d340 R08: ffffb914ffc02f80 R09: 0000000000000000
[ 48.270328] R10: ffff88e4c2d419e0 R11: 0000000000000001 R12: 0000000000000001
[ 48.270423] R13: 0000000000000000 R14: ffff88e4c36e4c00 R15: ffff88e4c3818400
[ 48.270566] FS: 0000000000000000(0000) GS:ffff88e4fbc00000(0000) knlGS:0000000000000000
[ 48.270679] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 48.270767] CR2: 0000000000000000 CR3: 0000000116422000 CR4: 00000000003506f0
[ 48.270926] Call Trace:
[ 48.271310] ? lockdep_init_map_type+0x47/0x240
[ 48.271469] blk_execute_rq+0x5c/0xe0
[ 48.271648] __scsi_execute+0x158/0x2b0
[ 48.271744] __scsi_scan_target+0x2e1/0x4d0
[ 48.271897] scsi_scan_target+0xd4/0xf0
[ 48.271990] sas_rphy_add+0x123/0x180
[ 48.272170] mptsas_add_end_device.isra.0.cold+0x89/0xc8
[ 48.272267] ? mptsas_refreshing_device_handles+0x70/0xd0
[ 48.272364] mptsas_scan_sas_topology+0x147/0x290
[ 48.272441] ? _raw_spin_unlock_irqrestore+0x3d/0x70
[ 48.272571] mptsas_probe+0x3b2/0x470
[ 48.272656] local_pci_probe+0x3d/0x70
[ 48.272739] pci_device_probe+0xc6/0x150
[ 48.272835] really_probe.part.0+0xa0/0x290
[ 48.272918] __driver_probe_device+0x8b/0x120
[ 48.272998] driver_probe_device+0x19/0x90
[ 48.273147] __driver_attach+0x79/0x120
[ 48.273212] ? __device_attach_driver+0x90/0x90
[ 48.273289] bus_for_each_dev+0x76/0xc0
[ 48.273376] bus_add_driver+0x109/0x1b0
[ 48.273455] driver_register+0x8a/0xe0
[ 48.273515] ? fusion_init+0x103/0x103
[ 48.273583] mptsas_init+0x10f/0x128
[ 48.273649] do_one_initcall+0x56/0x2e0
[ 48.273741] ? rcu_read_lock_sched_held+0x3a/0x70
[ 48.273828] kernel_init_freeable+0x24c/0x299
[ 48.273898] ? rest_init+0x250/0x250
[ 48.273969] kernel_init+0x11/0x110
[ 48.274099] ret_from_fork+0x22/0x30
[ 48.274304] irq event stamp: 10417319
[ 48.274371] hardirqs last enabled at (10417327): [<ffffffffa6ae0f22>] __up_console_sem+0x62/0x70
[ 48.274523] hardirqs last disabled at (10417334): [<ffffffffa6ae0f07>] __up_console_sem+0x47/0x70
[ 48.274637] softirqs last enabled at (10416158): [<ffffffffa6a73db8>] irq_exit_rcu+0xd8/0x120
[ 48.274756] softirqs last disabled at (10416145): [<ffffffffa6a73db8>] irq_exit_rcu+0xd8/0x120
[ 48.274937] ---[ end trace 3376dfd19d6a9ecf ]---

Bisect log is attached.

Guenter

---
# bad: [dcd68326d29b62f3039e4f4d23d3e38f24d37360] Merge tag 'devicetree-for-5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/robh/linux
# good: [8bb7eca972ad531c9b149c0a51ab43a417385813] Linux 5.15
git bisect start 'HEAD' 'v5.15'
# good: [84882cf72cd774cf16fd338bdbf00f69ac9f9194] Revert "net: avoid double accounting for pure zerocopy skbs"
git bisect good 84882cf72cd774cf16fd338bdbf00f69ac9f9194
# bad: [d2fac0afe89fe30c39eaa98dda71f7c4cea190c2] Merge tag 'audit-pr-20211101' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/audit
git bisect bad d2fac0afe89fe30c39eaa98dda71f7c4cea190c2
# bad: [8cb1ae19bfae92def42c985417cd6e894ddaa047] Merge tag 'x86-fpu-2021-11-01' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
git bisect bad 8cb1ae19bfae92def42c985417cd6e894ddaa047
# bad: [71ae42629e65edab618651c8ff9c88e1edd717aa] Merge tag 'for-5.16/passthrough-flag-2021-10-29' of git://git.kernel.dk/linux-block
git bisect bad 71ae42629e65edab618651c8ff9c88e1edd717aa
# bad: [33c8846c814c1c27c6e33af005042d15061f948b] Merge tag 'for-5.16/block-2021-10-29' of git://git.kernel.dk/linux-block
git bisect bad 33c8846c814c1c27c6e33af005042d15061f948b
# good: [057178cf518e699695a4b614a7a08c350b1fdcfd] fs: bdev: fix conflicting comment from lookup_bdev
git bisect good 057178cf518e699695a4b614a7a08c350b1fdcfd
# good: [203a31516616111b8eaaf00c16fa3fcaa25e6f81] mm/writeback: Add __folio_mark_dirty()
git bisect good 203a31516616111b8eaaf00c16fa3fcaa25e6f81
# bad: [02f7eab0095a47b45f48a4321d33de3569c59061] block: improve readability of blk_mq_end_request_batch()
git bisect bad 02f7eab0095a47b45f48a4321d33de3569c59061
# good: [54a88eb838d37af930c9f19e1930a4fba6789cb5] block: add single bio async direct IO helper
git bisect good 54a88eb838d37af930c9f19e1930a4fba6789cb5
# good: [842e39b013465a279fb60348427b9309427a29de] block: add async version of bio_set_polled
git bisect good 842e39b013465a279fb60348427b9309427a29de
# bad: [c7b84d4226adaa601e9f73574ef123d1500cf712] block: re-flow blk_mq_rq_ctx_init()
git bisect bad c7b84d4226adaa601e9f73574ef123d1500cf712
# bad: [fe6134f66906dfa16d4877cab60106275f48eef7] block: pass in blk_mq_tags to blk_mq_rq_ctx_init()
git bisect bad fe6134f66906dfa16d4877cab60106275f48eef7
# bad: [56f8da642bd827ef50a952e7bc3728c5830452be] block: add rq_flags to struct blk_mq_alloc_data
git bisect bad 56f8da642bd827ef50a952e7bc3728c5830452be
# first bad commit: [56f8da642bd827ef50a952e7bc3728c5830452be] block: add rq_flags to struct blk_mq_alloc_data