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BUG: KCSAN: data-race in delete_from_page_cache_batch / page_mapping

read to 0xffffea0004747f58 of 8 bytes by task 8879 on cpu 1:
 page_mapping+0x185/0x2a0 mm/util.c:665
 page_evictable+0x3a/0x110 mm/vmscan.c:4321
 __pagevec_lru_add_fn+0xe1/0x810 mm/swap.c:942
 pagevec_lru_move_fn+0xfe/0x180 mm/swap.c:211
 __pagevec_lru_add mm/swap.c:966 [inline]
 __lru_cache_add+0x120/0x1d0 mm/swap.c:406
 lru_cache_add+0x1f/0x30 mm/swap.c:442
 add_to_page_cache_lru+0x16a/0x260 mm/filemap.c:959
 pagecache_get_page+0x2ac/0x6f0 mm/filemap.c:1682
 grab_cache_page_write_begin+0x5d/0x90 mm/filemap.c:3255
 ext4_da_write_begin+0x1a3/0x810 fs/ext4/inode.c:3063
 generic_perform_write+0x136/0x320 mm/filemap.c:3305
 __generic_file_write_iter+0x251/0x380 mm/filemap.c:3434
 ext4_file_write_iter+0x1bd/0xa00 fs/ext4/file.c:268
 call_write_iter include/linux/fs.h:1895 [inline]
 do_iter_readv_writev+0x487/0x5b0 fs/read_write.c:693
 do_iter_write fs/read_write.c:970 [inline]
 do_iter_write+0x13b/0x3c0 fs/read_write.c:951
 vfs_iter_write+0x5c/0x80 fs/read_write.c:983
 iter_file_splice_write+0x4c0/0x7f0 fs/splice.c:746
 do_splice_from fs/splice.c:848 [inline]
 direct_splice_actor+0xa0/0xc0 fs/splice.c:1020
 splice_direct_to_actor+0x215/0x510 fs/splice.c:975
 do_splice_direct+0x161/0x1e0 fs/splice.c:1063
 do_sendfile+0x384/0x7f0 fs/read_write.c:1464
 __do_sys_sendfile64 fs/read_write.c:1525 [inline]
 __se_sys_sendfile64 fs/read_write.c:1511 [inline]
 __x64_sys_sendfile64+0x12a/0x140 fs/read_write.c:1511
 do_syscall_64+0xcc/0x370 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffffea0004747f58 of 8 bytes by task 8889 on cpu 0:
 page_cache_delete_batch mm/filemap.c:326 [inline]
 delete_from_page_cache_batch+0x674/0x790 mm/filemap.c:357
 truncate_inode_pages_range+0x593/0x1120 mm/truncate.c:366
 truncate_inode_pages mm/truncate.c:476 [inline]
 truncate_pagecache+0x60/0x80 mm/truncate.c:817
 ext4_setattr+0xb81/0x15a0 fs/ext4/inode.c:5659
 notify_change+0x7e1/0xaa0 fs/attr.c:337
 do_truncate+0xfb/0x180 fs/open.c:64
 handle_truncate fs/namei.c:2998 [inline]
 do_last fs/namei.c:3414 [inline]
 path_openat+0x2f48/0x36e0 fs/namei.c:3525
 do_filp_open+0x11e/0x1b0 fs/namei.c:3555
 do_sys_open+0x3b3/0x4f0 fs/open.c:1097
 ksys_open include/linux/syscalls.h:1385 [inline]
 __do_sys_creat fs/open.c:1155 [inline]
 __se_sys_creat fs/open.c:1153 [inline]
 __x64_sys_creat+0x45/0x60 fs/open.c:1153
 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: 0 PID: 8889 Comm: syz-executor.0 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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