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BUG: KCSAN: data-race in has_bh_in_lru / invalidate_bh_lrus_cpu

write to 0xffff888237c22f18 of 8 bytes by task 11997 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+0x256/0x280 mm/swap.c:623
 lru_add_drain+0x28/0x40 mm/swap.c:702
 free_pages_and_swap_cache+0x1d/0x1d0 mm/swap_state.c:317
 tlb_batch_pages_flush mm/mmu_gather.c:49 [inline]
 tlb_flush_mmu_free mm/mmu_gather.c:242 [inline]
 tlb_flush_mmu+0x597/0x5f0 mm/mmu_gather.c:249
 tlb_finish_mmu+0x86/0x100 mm/mmu_gather.c:340
 unmap_region+0x1b4/0x1e0 mm/mmap.c:2653
 __do_munmap+0xeb5/0x1340 mm/mmap.c:2884
 __do_sys_brk+0x261/0x580 mm/mmap.c:255
 __se_sys_brk mm/mmap.c:194 [inline]
 __x64_sys_brk+0x1b/0x20 mm/mmap.c:194
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888237c22f18 of 8 bytes by task 29679 on cpu 1:
 has_bh_in_lru+0x31/0x1c0 fs/buffer.c:1415
 smp_call_function_many_cond+0x236/0x620 kernel/smp.c:917
 on_each_cpu_cond_mask+0x31/0x40 kernel/smp.c:1135
 on_each_cpu_cond include/linux/smp.h:105 [inline]
 invalidate_bh_lrus+0x26/0x30 fs/buffer.c:1424
 invalidate_bdev+0x51/0x80 fs/block_dev.c:96
 __loop_clr_fd+0x521/0x850 drivers/block/loop.c:1399
 loop_clr_fd drivers/block/loop.c:1494 [inline]
 lo_ioctl+0xac5/0x13e0 drivers/block/loop.c:1850
 blkdev_ioctl+0x1d0/0x3f0 block/ioctl.c:589
 block_ioctl+0x6d/0x80 fs/block_dev.c:1421
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:860
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0xffff8881013b11a0 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 29679 Comm: syz-executor.4 Not tainted 5.14.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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