KCSAN: data-race in __bio_queue_enter / blk_mq_unfreeze_queue

Kernel	Title	Rank 🛈	Repro	Cause bisect	Fix bisect	Count	Last	Reported	Patched	Status
upstream	KCSAN: data-race in __bio_queue_enter / blk_mq_unfreeze_queue_nomemrestore (2) block	6				5	237d	342d	0/29	auto-obsoleted due to no activity on 2026/02/12 04:39
upstream	KCSAN: data-race in __bio_queue_enter / blk_mq_unfreeze_queue_nomemrestore (3) prio:high block	6				1	101d	101d	0/29	auto-obsoleted due to no activity on 2026/06/27 10:41

loop7: detected capacity change from 0 to 16384
==================================================================
BUG: KCSAN: data-race in __bio_queue_enter / blk_mq_unfreeze_queue_nomemrestore

read-write to 0xffff888102215d64 of 4 bytes by task 4433 on cpu 1:
 __blk_mq_unfreeze_queue block/blk-mq.c:227 [inline]
 blk_mq_unfreeze_queue_nomemrestore+0x38/0xc0 block/blk-mq.c:241
 blk_mq_unfreeze_queue include/linux/blk-mq.h:934 [inline]
 loop_set_status+0x4a5/0x5d0 drivers/block/loop.c:1313
 lo_ioctl+0x81a/0x1570 drivers/block/loop.c:-1
 blkdev_ioctl+0x35b/0x450 block/ioctl.c:698
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xc9/0x140 fs/ioctl.c:892
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:892
 x64_sys_call+0x168d/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888102215d64 of 4 bytes by task 4429 on cpu 0:
 __bio_queue_enter+0x1e1/0x5b0 block/blk-core.c:353
 bio_queue_enter block/blk.h:82 [inline]
 blk_mq_submit_bio+0x1a0/0xf50 block/blk-mq.c:3090
 __submit_bio+0xf5/0x510 block/blk-core.c:635
 __submit_bio_noacct_mq block/blk-core.c:722 [inline]
 submit_bio_noacct_nocheck+0x290/0x6f0 block/blk-core.c:751
 submit_bio_noacct+0x6e1/0x930 block/blk-core.c:874
 submit_bio+0x218/0x230 block/blk-core.c:916
 mpage_bio_submit_read fs/mpage.c:75 [inline]
 mpage_readahead+0x28c/0x2d0 fs/mpage.c:374
 blkdev_readahead+0x1c/0x30 block/fops.c:472
 read_pages+0xa1/0x470 mm/readahead.c:160
 page_cache_ra_unbounded+0x30d/0x350 mm/readahead.c:297
 do_page_cache_ra mm/readahead.c:327 [inline]
 page_cache_ra_order mm/readahead.c:532 [inline]
 page_cache_async_ra+0x41d/0x450 mm/readahead.c:687
 filemap_readahead mm/filemap.c:2559 [inline]
 filemap_get_pages+0x512/0x11b0 mm/filemap.c:2604
 filemap_splice_read+0x35a/0x930 mm/filemap.c:2980
 do_splice_read fs/splice.c:979 [inline]
 splice_direct_to_actor+0x26c/0x680 fs/splice.c:1083
 do_splice_direct_actor fs/splice.c:1201 [inline]
 do_splice_direct+0xd9/0x150 fs/splice.c:1227
 do_sendfile+0x40a/0x690 fs/read_write.c:1368
 __do_sys_sendfile64 fs/read_write.c:1429 [inline]
 __se_sys_sendfile64 fs/read_write.c:1415 [inline]
 __x64_sys_sendfile64+0x113/0x160 fs/read_write.c:1415
 x64_sys_call+0xfc3/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000001 -> 0x00000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 4429 Comm: syz.4.355 Not tainted 6.14.0-syzkaller-13423-ga8662bcd2ff1 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
==================================================================
syz.4.355 (4429) used greatest stack depth: 9928 bytes left