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BUG: KCSAN: data-race in __pagevec_lru_add / lru_add_drain_all

write to 0xffff88813bd27970 of 1 bytes by task 11085 on cpu 1:
 pagevec_reinit include/linux/pagevec.h:60 [inline]
 __pagevec_lru_add+0x24b/0x280 mm/swap.c:1031
 lru_add_drain_cpu+0x6a/0x250 mm/swap.c:616
 lru_add_drain+0x30/0x70 mm/swap.c:720
 exit_mmap+0x199/0x400 mm/mmap.c:3215
 __mmput+0xa2/0x220 kernel/fork.c:1083
 mmput+0x38/0x40 kernel/fork.c:1104
 exit_mm+0x32f/0x420 kernel/exit.c:500
 do_exit+0x3c8/0x1630 kernel/exit.c:810
 do_group_exit+0xc8/0x170 kernel/exit.c:920
 get_signal+0xd5e/0x1440 kernel/signal.c:2770
 arch_do_signal_or_restart+0x2a/0x270 arch/x86/kernel/signal.c:811
 handle_signal_work kernel/entry/common.c:147 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
 exit_to_user_mode_prepare+0x109/0x1a0 kernel/entry/common.c:201
 __syscall_exit_to_user_mode_work kernel/entry/common.c:291 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:302
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88813bd27970 of 1 bytes by task 11070 on cpu 0:
 pagevec_count include/linux/pagevec.h:65 [inline]
 lru_add_drain_all+0x108/0x3c0 mm/swap.c:823
 invalidate_bdev+0x50/0x70 fs/block_dev.c:97
 __loop_clr_fd+0x253/0x5a0 drivers/block/loop.c:1238
 loop_clr_fd drivers/block/loop.c:1334 [inline]
 lo_ioctl+0x9db/0x11d0 drivers/block/loop.c:1692
 blkdev_ioctl+0x1d0/0x3c0 block/ioctl.c:576
 block_ioctl+0x6d/0x80 fs/block_dev.c:1649
 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+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 11070 Comm: syz-executor.4 Not tainted 5.10.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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