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BUG: KCSAN: data-race in __pagevec_lru_add / lru_add_drain_all

write to 0xffff888237c26468 of 1 bytes by task 25807 on cpu 0:
 pagevec_reinit include/linux/pagevec.h:56 [inline]
 __pagevec_lru_add+0x24b/0x280 mm/swap.c:1017
 lru_add_drain_cpu+0x6a/0x260 mm/swap.c:606
 lru_add_drain mm/swap.c:710 [inline]
 __pagevec_release+0x57/0xa0 mm/swap.c:940
 pagevec_release include/linux/pagevec.h:81 [inline]
 shmem_undo_range+0x32f/0xe20 mm/shmem.c:931
 shmem_truncate_range mm/shmem.c:1030 [inline]
 shmem_evict_inode+0x115/0x5a0 mm/shmem.c:1132
 evict+0x1c8/0x3c0 fs/inode.c:578
 iput_final fs/inode.c:1654 [inline]
 iput+0x433/0x590 fs/inode.c:1680
 dentry_unlink_inode+0x23a/0x260 fs/dcache.c:374
 __dentry_kill+0x2af/0x4e0 fs/dcache.c:580
 dentry_kill fs/dcache.c:693 [inline]
 dput+0xc6/0x360 fs/dcache.c:886
 __fput+0x3ab/0x4e0 fs/file_table.c:293
 ____fput+0x11/0x20 fs/file_table.c:313
 task_work_run+0xae/0x130 kernel/task_work.c:140
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:174 [inline]
 exit_to_user_mode_prepare+0x151/0x170 kernel/entry/common.c:208
 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline]
 syscall_exit_to_user_mode+0x20/0x40 kernel/entry/common.c:301
 do_syscall_64+0x40/0x50 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888237c26468 of 1 bytes by task 25801 on cpu 1:
 pagevec_count include/linux/pagevec.h:61 [inline]
 lru_add_drain_all+0x108/0x3c0 mm/swap.c:813
 invalidate_bdev+0x50/0x70 fs/block_dev.c:96
 __loop_clr_fd+0x2e2/0x650 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:1671
 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+0x34/0x50 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 25801 Comm: syz-executor.2 Not tainted 5.12.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
loop2: detected capacity change from 0 to 4
EXT4-fs (loop2): invalid first ino: 0