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BUG: KCSAN: data-race in __pagevec_lru_add / lru_add_drain_all

write to 0xffff88813bd27550 of 1 bytes by task 23390 on cpu 1:
 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+0x30/0x70 mm/swap.c:710
 follow_page_pte+0x9ae/0xb90 mm/gup.c:494
 follow_pmd_mask+0x4b0/0xee0 mm/gup.c:572
 follow_pud_mask mm/gup.c:667 [inline]
 follow_p4d_mask mm/gup.c:693 [inline]
 follow_page_mask+0x382/0x540 mm/gup.c:752
 __get_user_pages+0xa00/0x1000 mm/gup.c:1067
 populate_vma_page_range mm/gup.c:1402 [inline]
 __mm_populate+0x24d/0x380 mm/gup.c:1450
 mm_populate include/linux/mm.h:2582 [inline]
 __do_sys_mlockall+0x24c/0x2d0 mm/mlock.c:798
 __se_sys_mlockall mm/mlock.c:774 [inline]
 __x64_sys_mlockall+0x1a/0x20 mm/mlock.c:774
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88813bd27550 of 1 bytes by task 13446 on cpu 0:
 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
 ext4_put_super+0x5d5/0x950 fs/ext4/super.c:1229
 generic_shutdown_super+0xde/0x210 fs/super.c:464
 kill_block_super+0x4a/0x90 fs/super.c:1394
 deactivate_locked_super+0x6a/0xb0 fs/super.c:335
 deactivate_super+0x85/0x90 fs/super.c:366
 cleanup_mnt+0x277/0x2e0 fs/namespace.c:1136
 __cleanup_mnt+0x15/0x20 fs/namespace.c:1143
 task_work_run+0x8e/0x110 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+0x17c/0x1b0 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+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 13446 Comm: syz-executor.5 Tainted: G        W         5.12.0-rc5-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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