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BUG: KCSAN: data-race in __filemap_add_folio / file_write_and_wait_range

read-write to 0xffff88812e8ba8b0 of 8 bytes by task 14348 on cpu 0:
 __filemap_add_folio+0x2d9/0x7f0 mm/filemap.c:904
 filemap_add_folio+0x6b/0x150 mm/filemap.c:959
 __filemap_get_folio+0x4bd/0x680 mm/filemap.c:2003
 pagecache_get_page+0x26/0x190 mm/folio-compat.c:126
 grab_cache_page_write_begin+0x3f/0x50 mm/folio-compat.c:140
 ext4_da_write_begin+0x271/0x530 fs/ext4/inode.c:2967
 generic_perform_write+0x1d6/0x3f0 mm/filemap.c:3787
 ext4_buffered_write_iter+0x199/0x280 fs/ext4/file.c:270
 ext4_file_write_iter+0x211/0xdf0
 do_iter_readv_writev+0x27b/0x300
 do_iter_write+0x16f/0x5c0 fs/read_write.c:852
 vfs_iter_write+0x4c/0x70 fs/read_write.c:893
 iter_file_splice_write+0x44a/0x7c0 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x660 fs/splice.c:891
 do_splice_direct+0xfb/0x180 fs/splice.c:979
 do_sendfile+0x3ad/0x900 fs/read_write.c:1246
 __do_sys_sendfile64 fs/read_write.c:1311 [inline]
 __se_sys_sendfile64 fs/read_write.c:1297 [inline]
 __x64_sys_sendfile64+0x10c/0x150 fs/read_write.c:1297
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88812e8ba8b0 of 8 bytes by task 14349 on cpu 1:
 mapping_needs_writeback mm/filemap.c:627 [inline]
 file_write_and_wait_range+0x4b/0x170 mm/filemap.c:778
 ext4_sync_file+0xad/0x560 fs/ext4/fsync.c:151
 vfs_fsync_range+0x107/0x120 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2732 [inline]
 ext4_buffered_write_iter+0x23f/0x280 fs/ext4/file.c:277
 ext4_file_write_iter+0x211/0xdf0
 do_iter_readv_writev+0x27b/0x300
 do_iter_write+0x16f/0x5c0 fs/read_write.c:852
 vfs_iter_write+0x4c/0x70 fs/read_write.c:893
 iter_file_splice_write+0x44a/0x7c0 fs/splice.c:689
 do_splice_from fs/splice.c:767 [inline]
 direct_splice_actor+0x80/0xa0 fs/splice.c:936
 splice_direct_to_actor+0x345/0x660 fs/splice.c:891
 do_splice_direct+0xfb/0x180 fs/splice.c:979
 do_sendfile+0x3ad/0x900 fs/read_write.c:1246
 __do_sys_sendfile64 fs/read_write.c:1311 [inline]
 __se_sys_sendfile64 fs/read_write.c:1297 [inline]
 __x64_sys_sendfile64+0x10c/0x150 fs/read_write.c:1297
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000000002779 -> 0x000000000000277a

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 14349 Comm: syz-executor.4 Not tainted 5.18.0-rc6-syzkaller-00015-g0ac824f379fb-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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