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BUG: KCSAN: data-race in has_bh_in_lru / invalidate_bh_lrus_cpu

write to 0xffff888237c42f10 of 8 bytes by task 19698 on cpu 0:
 __invalidate_bh_lrus fs/buffer.c:1393 [inline]
 invalidate_bh_lrus_cpu+0xad/0xe0 fs/buffer.c:1434
 lru_add_drain_cpu+0x243/0x270 mm/swap.c:645
 lru_add_drain mm/swap.c:724 [inline]
 __pagevec_release+0x57/0xa0 mm/swap.c:989
 pagevec_release include/linux/pagevec.h:81 [inline]
 __invalidate_mapping_pages+0x27f/0x310 mm/truncate.c:507
 invalidate_mapping_pages+0x23/0x30 mm/truncate.c:532
 invalidate_bdev+0x61/0x70 fs/block_dev.c:97
 __loop_clr_fd+0x566/0x8f0 drivers/block/loop.c:1402
 loop_clr_fd drivers/block/loop.c:1496 [inline]
 lo_ioctl+0xa48/0x1340 drivers/block/loop.c:1852
 blkdev_ioctl+0x1d0/0x3c0 block/ioctl.c:585
 block_ioctl+0x6d/0x80 fs/block_dev.c:1604
 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_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888237c42f10 of 8 bytes by task 19702 on cpu 1:
 has_bh_in_lru+0x31/0x1c0 fs/buffer.c:1415
 smp_call_function_many_cond+0x226/0x620 kernel/smp.c:915
 on_each_cpu_cond_mask+0x31/0x40 kernel/smp.c:1133
 on_each_cpu_cond include/linux/smp.h:105 [inline]
 invalidate_bh_lrus+0x26/0x30 fs/buffer.c:1424
 invalidate_bdev+0x4b/0x70 fs/block_dev.c:95
 __loop_clr_fd+0x566/0x8f0 drivers/block/loop.c:1402
 loop_clr_fd drivers/block/loop.c:1496 [inline]
 lo_ioctl+0xa48/0x1340 drivers/block/loop.c:1852
 blkdev_ioctl+0x1d0/0x3c0 block/ioctl.c:585
 block_ioctl+0x6d/0x80 fs/block_dev.c:1604
 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_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffff8881023004e0 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 19702 Comm: syz-executor.3 Tainted: G        W         5.14.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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