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BUG: KCSAN: data-race in blk_mq_unfreeze_queue / blk_queue_enter

write to 0xffff888129f3382c of 4 bytes by task 28395 on cpu 1:
 blk_mq_unfreeze_queue+0x3c/0xc0 block/blk-mq.c:192
 loop_set_status+0x69d/0x7d0 drivers/block/loop.c:1416
 lo_ioctl+0x757/0x1190 drivers/block/loop.c:1495
 __blkdev_driver_ioctl block/ioctl.c:224 [inline]
 blkdev_ioctl+0x1cf/0x410 block/ioctl.c:620
 block_ioctl+0x6d/0x80 fs/block_dev.c:1871
 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 0xffff888129f3382c of 4 bytes by task 21772 on cpu 0:
 blk_queue_enter+0x1da/0x4f0 block/blk-core.c:462
 bio_queue_enter block/blk-core.c:478 [inline]
 __submit_bio_noacct_mq block/blk-core.c:1171 [inline]
 submit_bio_noacct+0x700/0x950 block/blk-core.c:1213
 submit_bio+0x200/0x370 block/blk-core.c:1283
 mpage_bio_submit fs/mpage.c:66 [inline]
 mpage_readahead+0x2fa/0x340 fs/mpage.c:395
 blkdev_readahead+0x18/0x20 fs/block_dev.c:608
 read_pages+0x9c/0x700 mm/readahead.c:130
 page_cache_readahead_unbounded+0x41a/0x470 mm/readahead.c:244
 __do_page_cache_readahead mm/readahead.c:273 [inline]
 force_page_cache_readahead+0x1ec/0x220 mm/readahead.c:303
 page_cache_sync_readahead+0x191/0x1a0 mm/readahead.c:580
 generic_file_buffered_read+0x2de/0x1fa0 mm/filemap.c:2199
 generic_file_read_iter+0x7d/0x3e0 mm/filemap.c:2507
 blkdev_read_iter+0xb3/0xc0 fs/block_dev.c:1927
 call_read_iter include/linux/fs.h:1876 [inline]
 new_sync_read fs/read_write.c:415 [inline]
 vfs_read+0x57a/0x5e0 fs/read_write.c:481
 ksys_read+0xce/0x180 fs/read_write.c:615
 __do_sys_read fs/read_write.c:625 [inline]
 __se_sys_read fs/read_write.c:623 [inline]
 __x64_sys_read+0x3e/0x50 fs/read_write.c:623
 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: 21772 Comm: systemd-udevd Not tainted 5.9.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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