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BUG: KCSAN: data-race in blk_freeze_queue / blk_queue_enter

write to 0xffff888101aced8c of 4 bytes by task 17001 on cpu 1:
 blk_freeze_queue_start block/blk-mq.c:138 [inline]
 blk_freeze_queue+0x40/0xb0 block/blk-mq.c:177
 blk_mq_freeze_queue+0x11/0x20 block/blk-mq.c:187
 __loop_clr_fd+0x148/0x650 drivers/block/loop.c:1219
 loop_clr_fd drivers/block/loop.c:1336 [inline]
 lo_ioctl+0x9eb/0x11f0 drivers/block/loop.c:1694
 blkdev_ioctl+0x1d0/0x3c0 block/ioctl.c:585
 block_ioctl+0x6d/0x80 fs/block_dev.c:1664
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:1055
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888101aced8c of 4 bytes by task 16971 on cpu 0:
 blk_queue_enter+0x2b8/0x560 block/blk-core.c:469
 bio_queue_enter block/blk-core.c:484 [inline]
 __submit_bio_noacct_mq block/blk-core.c:1005 [inline]
 submit_bio_noacct+0x6d4/0x7e0 block/blk-core.c:1047
 submit_bio+0x16d/0x2b0 block/blk-core.c:1090
 submit_bio_wait+0x86/0xc0 block/bio.c:1155
 blkdev_issue_flush+0x6c/0x90 block/blk-flush.c:446
 blkdev_fsync+0x6f/0xa0 fs/block_dev.c:704
 vfs_fsync_range+0x107/0x120 fs/sync.c:200
 generic_write_sync include/linux/fs.h:2984 [inline]
 blkdev_write_iter+0x264/0x2a0 fs/block_dev.c:1702
 call_write_iter include/linux/fs.h:2116 [inline]
 do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740
 do_iter_write+0x112/0x4c0 fs/read_write.c:866
 vfs_iter_write+0x4c/0x70 fs/read_write.c:907
 iter_file_splice_write+0x40a/0x750 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x650 fs/splice.c:891
 do_splice_direct+0xf5/0x170 fs/splice.c:979
 do_sendfile+0x773/0xda0 fs/read_write.c:1260
 __do_sys_sendfile64 fs/read_write.c:1325 [inline]
 __se_sys_sendfile64 fs/read_write.c:1311 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1311
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 16971 Comm: syz-executor.5 Not tainted 5.12.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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