[moderation] [block?] KCSAN: data-race in __blk_mq_alloc_driver_tag / bt_tags_for_each

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 5eff55d725a4 Merge tag 'platform-drivers-x86-v6.7-7' of gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1792e8fee80000
kernel config: https://syzkaller.appspot.com/x/.config?x=17e138c8fc533c5e
dashboard link: https://syzkaller.appspot.com/bug?extid=c75a5f3d44cb08fdff32
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
CC: [ax...@kernel.dk linux...@vger.kernel.org linux-...@vger.kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ed8fb2b49f07/disk-5eff55d7.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/dd6ae49f0600/vmlinux-5eff55d7.xz
kernel image: https://storage.googleapis.com/syzbot-assets/f59a0e5ba0f3/bzImage-5eff55d7.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c75a5f...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __blk_mq_alloc_driver_tag / bt_tags_for_each

write to 0xffff88810297afa0 of 4 bytes by task 29577 on cpu 1:
__blk_mq_alloc_driver_tag+0x180/0x380 block/blk-mq.c:1784
blk_mq_get_driver_tag block/blk-mq.h:354 [inline]
blk_mq_prep_dispatch_rq block/blk-mq.c:1954 [inline]
blk_mq_dispatch_rq_list+0x1f8/0x1090 block/blk-mq.c:2034
__blk_mq_sched_dispatch_requests+0x1ce/0xd20 block/blk-mq-sched.c:301
blk_mq_sched_dispatch_requests+0x99/0x100 block/blk-mq-sched.c:333
blk_mq_run_hw_queue+0x2a4/0x4c0 block/blk-mq.c:2264
blk_mq_get_tag+0x21f/0x590 block/blk-mq-tag.c:170
__blk_mq_alloc_requests+0x642/0x9e0 block/blk-mq.c:501
blk_mq_get_new_requests block/blk-mq.c:2884 [inline]
blk_mq_submit_bio+0x468/0xd90 block/blk-mq.c:2982
__submit_bio+0x11c/0x350 block/blk-core.c:607
__submit_bio_noacct_mq block/blk-core.c:686 [inline]
submit_bio_noacct_nocheck+0x4ad/0x5e0 block/blk-core.c:715
submit_bio_noacct+0x70c/0x8c0 block/blk-core.c:809
submit_bio+0xb7/0xc0 block/blk-core.c:842
ext4_io_submit fs/ext4/page-io.c:378 [inline]
io_submit_add_bh fs/ext4/page-io.c:419 [inline]
ext4_bio_write_folio+0x6c0/0x9a0 fs/ext4/page-io.c:563
mpage_submit_folio fs/ext4/inode.c:1875 [inline]
mpage_map_and_submit_buffers fs/ext4/inode.c:2121 [inline]
mpage_map_and_submit_extent fs/ext4/inode.c:2260 [inline]
ext4_do_writepages+0x139f/0x2100 fs/ext4/inode.c:2685
ext4_writepages+0x15e/0x2e0 fs/ext4/inode.c:2774
do_writepages+0x1c2/0x340 mm/page-writeback.c:2553
filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:387
__filemap_fdatawrite_range mm/filemap.c:420 [inline]
__filemap_fdatawrite mm/filemap.c:426 [inline]
filemap_flush+0x95/0xc0 mm/filemap.c:453
ext4_alloc_da_blocks+0x50/0x130 fs/ext4/inode.c:3077
ext4_release_file+0x5f/0x1c0 fs/ext4/file.c:169
__fput+0x299/0x630 fs/file_table.c:394
____fput+0x15/0x20 fs/file_table.c:422
task_work_run+0x135/0x1a0 kernel/task_work.c:180
exit_task_work include/linux/task_work.h:38 [inline]
do_exit+0x604/0x16d0 kernel/exit.c:869
do_group_exit+0x101/0x150 kernel/exit.c:1018
get_signal+0xf4e/0x10a0 kernel/signal.c:2904
arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:309
exit_to_user_mode_loop+0x6f/0xe0 kernel/entry/common.c:168
exit_to_user_mode_prepare+0x6c/0xb0 kernel/entry/common.c:204
irqentry_exit_to_user_mode+0x9/0x20 kernel/entry/common.c:309
irqentry_exit+0x12/0x40 kernel/entry/common.c:412
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570

read to 0xffff88810297afa0 of 4 bytes by task 23915 on cpu 0:
blk_mq_find_and_get_req block/blk-mq-tag.c:260 [inline]
bt_tags_iter block/blk-mq-tag.c:356 [inline]
__sbitmap_for_each_set include/linux/sbitmap.h:281 [inline]
sbitmap_for_each_set include/linux/sbitmap.h:302 [inline]
bt_tags_for_each+0x2e2/0x500 block/blk-mq-tag.c:391
__blk_mq_all_tag_iter block/blk-mq-tag.c:402 [inline]
blk_mq_tagset_busy_iter+0x114/0x150 block/blk-mq-tag.c:446
scsi_host_busy+0x4f/0x80 drivers/scsi/hosts.c:604
scsi_host_queue_ready drivers/scsi/scsi_lib.c:1341 [inline]
scsi_queue_rq+0x310/0x1a30 drivers/scsi/scsi_lib.c:1735
blk_mq_dispatch_rq_list+0x2d9/0x1090 block/blk-mq.c:2049
__blk_mq_do_dispatch_sched block/blk-mq-sched.c:170 [inline]
blk_mq_do_dispatch_sched block/blk-mq-sched.c:184 [inline]
__blk_mq_sched_dispatch_requests+0x5ec/0xd20 block/blk-mq-sched.c:309
blk_mq_sched_dispatch_requests+0x99/0x100 block/blk-mq-sched.c:333
blk_mq_run_hw_queue+0x2a4/0x4c0 block/blk-mq.c:2264
blk_mq_get_tag+0x479/0x590 block/blk-mq-tag.c:170
__blk_mq_alloc_requests+0x642/0x9e0 block/blk-mq.c:501
blk_mq_get_new_requests block/blk-mq.c:2884 [inline]
blk_mq_submit_bio+0x468/0xd90 block/blk-mq.c:2982
__submit_bio+0x11c/0x350 block/blk-core.c:607
__submit_bio_noacct_mq block/blk-core.c:686 [inline]
submit_bio_noacct_nocheck+0x449/0x5e0 block/blk-core.c:715
submit_bio_noacct+0x70c/0x8c0 block/blk-core.c:809
submit_bio+0xb7/0xc0 block/blk-core.c:842
ext4_io_submit+0x8a/0xa0 fs/ext4/page-io.c:378
ext4_do_writepages+0xb3a/0x2100 fs/ext4/inode.c:2705
ext4_writepages+0x15e/0x2e0 fs/ext4/inode.c:2774
do_writepages+0x1c2/0x340 mm/page-writeback.c:2553
filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:387
__filemap_fdatawrite_range mm/filemap.c:420 [inline]
__filemap_fdatawrite mm/filemap.c:426 [inline]
filemap_flush+0x95/0xc0 mm/filemap.c:453
ext4_alloc_da_blocks+0x50/0x130 fs/ext4/inode.c:3077
ext4_release_file+0x5f/0x1c0 fs/ext4/file.c:169
__fput+0x299/0x630 fs/file_table.c:394
____fput+0x15/0x20 fs/file_table.c:422
task_work_run+0x135/0x1a0 kernel/task_work.c:180
exit_task_work include/linux/task_work.h:38 [inline]
do_exit+0x604/0x16d0 kernel/exit.c:869
do_group_exit+0x101/0x150 kernel/exit.c:1018
get_signal+0xf4e/0x10a0 kernel/signal.c:2904
arch_do_signal_or_restart+0x95/0x4b0 arch/x86/kernel/signal.c:309
exit_to_user_mode_loop+0x6f/0xe0 kernel/entry/common.c:168
exit_to_user_mode_prepare+0x6c/0xb0 kernel/entry/common.c:204
irqentry_exit_to_user_mode+0x9/0x20 kernel/entry/common.c:309
irqentry_exit+0x12/0x40 kernel/entry/common.c:412
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570

value changed: 0xffffffff -> 0x00001a52

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 23915 Comm: syz-executor.3 Not tainted 6.7.0-rc8-syzkaller-00055-g5eff55d725a4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.