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BUG: KCSAN: data-race in has_bh_in_lru / invalidate_bh_lru

write to 0xffff88813bc27f48 of 8 bytes by task 26527 on cpu 0:
 invalidate_bh_lru+0x9d/0xf0 fs/buffer.c:1419
 on_each_cpu_cond_mask+0x98/0x120 kernel/smp.c:908
 on_each_cpu_cond+0x2f/0x40 kernel/smp.c:918
 invalidate_bh_lrus+0x1f/0x20 fs/buffer.c:1439
 invalidate_bdev+0x4b/0x70 fs/block_dev.c:95
 __loop_clr_fd+0x2c5/0x630 drivers/block/loop.c:1241
 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:583
 block_ioctl+0x6d/0x80 fs/block_dev.c:1667
 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+0x44/0xae

read to 0xffff88813bc27f48 of 8 bytes by task 26523 on cpu 1:
 has_bh_in_lru+0x31/0x1c0 fs/buffer.c:1430
 smp_call_function_many_cond+0x49c/0x640 kernel/smp.c:651
 on_each_cpu_cond_mask+0x52/0x120 kernel/smp.c:903
 on_each_cpu_cond+0x2f/0x40 kernel/smp.c:918
 invalidate_bh_lrus+0x1f/0x20 fs/buffer.c:1439
 invalidate_bdev+0x4b/0x70 fs/block_dev.c:95
 __loop_clr_fd+0x2c5/0x630 drivers/block/loop.c:1241
 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:583
 block_ioctl+0x6d/0x80 fs/block_dev.c:1667
 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+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 26523 Comm: syz-executor.0 Tainted: G        W         5.12.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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