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BUG: KCSAN: data-race in __lru_add_drain_all / lru_cache_add

write to 0xffff888237d42528 of 1 bytes by task 22 on cpu 1:
 pagevec_add include/linux/pagevec.h:74 [inline]
 pagevec_add_and_need_flush mm/swap.c:244 [inline]
 lru_cache_add+0x75/0x150 mm/swap.c:474
 shmem_getpage_gfp+0xc9b/0x13e0 mm/shmem.c:1944
 shmem_getpage mm/shmem.c:155 [inline]
 shmem_file_read_iter+0x1ae/0x5d0 mm/shmem.c:2559
 call_read_iter include/linux/fs.h:2152 [inline]
 do_iter_readv_writev+0x2ea/0x370 fs/read_write.c:727
 do_iter_read+0x192/0x5d0 fs/read_write.c:790
 vfs_iter_read+0x4c/0x70 fs/read_write.c:832
 lo_read_simple drivers/block/loop.c:404 [inline]
 do_req_filebacked drivers/block/loop.c:675 [inline]
 loop_handle_cmd drivers/block/loop.c:2202 [inline]
 loop_process_work+0x110b/0x1850 drivers/block/loop.c:2242
 loop_rootcg_workfn+0x1b/0x20 drivers/block/loop.c:2273
 process_one_work+0x402/0x910 kernel/workqueue.c:2297
 worker_thread+0x636/0xae0 kernel/workqueue.c:2444
 kthread+0x262/0x280 kernel/kthread.c:319
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:295

read to 0xffff888237d42528 of 1 bytes by task 1780 on cpu 0:
 pagevec_count include/linux/pagevec.h:61 [inline]
 __lru_add_drain_all+0x12c/0x3e0 mm/swap.c:828
 lru_add_drain_all+0xc/0x10 mm/swap.c:850
 invalidate_bdev+0x56/0x80 fs/block_dev.c:97
 ext4_put_super+0x5d0/0x8c0 fs/ext4/super.c:1238
 generic_shutdown_super+0xe1/0x230 fs/super.c:465
 kill_block_super+0x4a/0x90 fs/super.c:1395
 deactivate_locked_super+0x65/0xd0 fs/super.c:335
 deactivate_super+0x85/0x90 fs/super.c:366
 cleanup_mnt+0x267/0x2d0 fs/namespace.c:1136
 __cleanup_mnt+0x15/0x20 fs/namespace.c:1143
 task_work_run+0xae/0x130 kernel/task_work.c:164
 tracehook_notify_resume include/linux/tracehook.h:189 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:175 [inline]
 exit_to_user_mode_prepare+0x156/0x190 kernel/entry/common.c:209
 __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+0x49/0x90 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0a -> 0x0c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1780 Comm: syz-executor.3 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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