syzbot

==================================================================
BUG: KCSAN: data-race in blk_mq_unfreeze_queue / blk_queue_enter

read-write to 0xffff888102713d94 of 4 bytes by task 2389 on cpu 1:
 blk_mq_unfreeze_queue+0x34/0xb0 block/blk-mq.c:194
 loop_set_status+0x69b/0x7c0 drivers/block/loop.c:1405
 lo_ioctl+0x743/0x11d0 drivers/block/loop.c:1484
 blkdev_ioctl+0x1d0/0x3c0 block/ioctl.c:576
 block_ioctl+0x6d/0x80 fs/block_dev.c:1650
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:739
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:739
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888102713d94 of 4 bytes by task 30845 on cpu 0:
 blk_queue_enter+0x208/0x540 block/blk-core.c:468
 bio_queue_enter block/blk-core.c:483 [inline]
 __submit_bio_noacct_mq block/blk-core.c:1019 [inline]
 submit_bio_noacct+0x6f8/0x910 block/blk-core.c:1061
 submit_bio+0x1f3/0x350 block/blk-core.c:1131
 mpage_bio_submit fs/mpage.c:66 [inline]
 mpage_readahead+0x2ff/0x340 fs/mpage.c:395
 blkdev_readahead+0x18/0x20 fs/block_dev.c:628
 read_pages+0xa0/0x6e0 mm/readahead.c:130
 page_cache_ra_unbounded+0x464/0x4c0 mm/readahead.c:238
 do_page_cache_ra mm/readahead.c:267 [inline]
 force_page_cache_ra+0x226/0x260 mm/readahead.c:298
 page_cache_sync_ra+0x194/0x1c0 mm/readahead.c:572
 page_cache_sync_readahead include/linux/pagemap.h:839 [inline]
 generic_file_buffered_read_get_pages+0x234/0xaf0 mm/filemap.c:2361
 generic_file_buffered_read+0x27f/0x9a0 mm/filemap.c:2481
 generic_file_read_iter+0x80/0x3d0 mm/filemap.c:2633
 blkdev_read_iter+0xb3/0xc0 fs/block_dev.c:1706
 call_read_iter include/linux/fs.h:1895 [inline]
 new_sync_read fs/read_write.c:415 [inline]
 vfs_read+0x552/0x5c0 fs/read_write.c:496
 ksys_read+0xce/0x180 fs/read_write.c:634
 __do_sys_read fs/read_write.c:644 [inline]
 __se_sys_read fs/read_write.c:642 [inline]
 __x64_sys_read+0x3e/0x50 fs/read_write.c:642
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 30845 Comm: systemd-udevd Not tainted 5.11.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================