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BUG: KCSAN: data-race in lru_add_drain_all / pagevec_lru_move_fn

read to 0xffff88812bf27620 of 1 bytes by task 9251 on cpu 0:
 lru_add_drain_all+0xf5/0x350 mm/swap.c:728
 invalidate_bdev+0x6e/0x90 fs/block_dev.c:97
 __loop_clr_fd+0x250/0x720 drivers/block/loop.c:1128
 loop_clr_fd drivers/block/loop.c:1224 [inline]
 lo_ioctl+0x24c/0xc80 drivers/block/loop.c:1593
 __blkdev_driver_ioctl block/ioctl.c:304 [inline]
 blkdev_ioctl+0x979/0x1160 block/ioctl.c:606
 block_ioctl+0x95/0xc0 fs/block_dev.c:1954
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:509 [inline]
 do_vfs_ioctl+0x991/0xc60 fs/ioctl.c:696
 ksys_ioctl+0xbd/0xe0 fs/ioctl.c:713
 __do_sys_ioctl fs/ioctl.c:720 [inline]
 __se_sys_ioctl fs/ioctl.c:718 [inline]
 __x64_sys_ioctl+0x4c/0x60 fs/ioctl.c:718
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff88812bf27620 of 1 bytes by task 9258 on cpu 1:
 pagevec_reinit include/linux/pagevec.h:63 [inline]
 pagevec_lru_move_fn+0x163/0x180 mm/swap.c:216
 __pagevec_lru_add mm/swap.c:966 [inline]
 lru_add_drain_cpu+0x178/0x2e0 mm/swap.c:594
 lru_add_drain+0x35/0x80 mm/swap.c:689
 unmap_region+0x6b/0x270 mm/mmap.c:2622
 __do_munmap+0x661/0xb60 mm/mmap.c:2845
 do_munmap mm/mmap.c:2856 [inline]
 mmap_region+0x165/0xd50 mm/mmap.c:1749
 do_mmap+0x6d4/0xba0 mm/mmap.c:1577
 do_mmap_pgoff include/linux/mm.h:2348 [inline]
 vm_mmap_pgoff+0x12d/0x190 mm/util.c:496
 ksys_mmap_pgoff+0x2d8/0x420 mm/mmap.c:1629
 __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
 __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
 __x64_sys_mmap+0x2e/0x40 arch/x86/kernel/sys_x86_64.c:91
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 9258 Comm: blkid Not tainted 5.4.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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