[moderation] [block?] KCSAN: data-race in __bio_queue_enter / blk_mq_unfreeze_queue_nomemrestore (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: ec299e4dc21e Merge tag 'bitmap-for-6.17-rc5' of https://gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17ecde62580000
kernel config: https://syzkaller.appspot.com/x/.config?x=52ae2e92d7a28724
dashboard link: https://syzkaller.appspot.com/bug?extid=48726f682fe776e69b74
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
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/99934f8a7b9c/disk-ec299e4d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/ab78b281a70e/vmlinux-ec299e4d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/154d9c935ff8/bzImage-ec299e4d.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+48726f...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __bio_queue_enter / blk_mq_unfreeze_queue_nomemrestore

read-write to 0xffff88810242a1b4 of 4 bytes by task 11980 on cpu 1:
__blk_mq_unfreeze_queue block/blk-mq.c:217 [inline]
blk_mq_unfreeze_queue_nomemrestore+0x38/0xc0 block/blk-mq.c:231
blk_mq_unfreeze_queue include/linux/blk-mq.h:940 [inline]
loop_set_status+0x3a3/0x6a0 drivers/block/loop.c:1264
loop_set_status_old drivers/block/loop.c:1360 [inline]
lo_ioctl+0x71b/0x12b0 drivers/block/loop.c:1549
blkdev_ioctl+0x34f/0x440 block/ioctl.c:705
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:598 [inline]
__se_sys_ioctl+0xce/0x140 fs/ioctl.c:584
__x64_sys_ioctl+0x43/0x50 fs/ioctl.c:584
x64_sys_call+0x1816/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:17
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810242a1b4 of 4 bytes by task 11976 on cpu 0:
__bio_queue_enter+0x279/0x5a0 block/blk-core.c:353
bio_queue_enter block/blk.h:93 [inline]
blk_mq_submit_bio+0x196/0x1020 block/blk-mq.c:3144
__submit_bio+0xed/0x4d0 block/blk-core.c:635
__submit_bio_noacct_mq block/blk-core.c:722 [inline]
submit_bio_noacct_nocheck+0x208/0x6a0 block/blk-core.c:751
submit_bio_noacct+0x6ed/0x920 block/blk-core.c:874
submit_bio+0x2a6/0x2c0 block/blk-core.c:916
mpage_bio_submit_read fs/mpage.c:75 [inline]
mpage_readahead+0x295/0x2e0 fs/mpage.c:374
blkdev_readahead+0x1c/0x30 block/fops.c:496
read_pages+0xa0/0x480 mm/readahead.c:160
page_cache_ra_unbounded+0x347/0x380 mm/readahead.c:297
do_page_cache_ra mm/readahead.c:327 [inline]
page_cache_ra_order mm/readahead.c:529 [inline]
page_cache_async_ra+0x4d0/0x4e0 mm/readahead.c:689
filemap_readahead mm/filemap.c:2572 [inline]
filemap_get_pages+0x510/0x1150 mm/filemap.c:2617
filemap_splice_read+0x3a9/0x740 mm/filemap.c:2991
do_splice_read fs/splice.c:982 [inline]
splice_direct_to_actor+0x26c/0x680 fs/splice.c:1086
do_splice_direct_actor fs/splice.c:1204 [inline]
do_splice_direct+0xda/0x150 fs/splice.c:1230
do_sendfile+0x380/0x650 fs/read_write.c:1370
__do_sys_sendfile64 fs/read_write.c:1431 [inline]
__se_sys_sendfile64 fs/read_write.c:1417 [inline]
__x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1417
x64_sys_call+0x2bb0/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:41
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xd2/0x200 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: 11976 Comm: syz.1.2606 Not tainted syzkaller #0 PREEMPT(voluntary)
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
==================================================================


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