syzbot

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BUG: KCSAN: data-race in xas_find_marked / xas_set_mark

read-write to 0xffff88810964e478 of 8 bytes by task 4405 on cpu 1:
 instrument_read_write include/linux/instrumented.h:55 [inline]
 __instrument_read_write_bitop include/asm-generic/bitops/instrumented-non-atomic.h:84 [inline]
 ___test_and_set_bit include/asm-generic/bitops/instrumented-non-atomic.h:99 [inline]
 node_set_mark lib/xarray.c:93 [inline]
 xas_set_mark+0x86/0x140 lib/xarray.c:887
 tag_pages_for_writeback+0xaa/0x2a0 mm/page-writeback.c:2350
 write_cache_pages+0x1a5/0x760 mm/page-writeback.c:2420
 do_writepages+0x212/0x340 mm/page-writeback.c:2556
 filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:390
 __filemap_fdatawrite_range mm/filemap.c:423 [inline]
 file_write_and_wait_range+0xfa/0x190 mm/filemap.c:781
 blkdev_fsync+0x39/0x80 block/fops.c:457
 vfs_fsync_range+0x10b/0x120 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2469 [inline]
 blkdev_write_iter+0x36d/0x3d0 block/fops.c:551
 do_iter_write+0x4ae/0x770 fs/read_write.c:860
 vfs_iter_write+0x50/0x70 fs/read_write.c:901
 iter_file_splice_write+0x456/0x7d0 fs/splice.c:795
 do_splice_from fs/splice.c:873 [inline]
 direct_splice_actor+0x84/0xa0 fs/splice.c:1039
 splice_direct_to_actor+0x2ee/0x5f0 fs/splice.c:994
 do_splice_direct+0x104/0x180 fs/splice.c:1082
 do_sendfile+0x3b8/0x950 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff88810964e478 of 8 bytes by task 4406 on cpu 0:
 xas_find_chunk include/linux/xarray.h:1705 [inline]
 xas_find_marked+0x216/0x660 lib/xarray.c:1356
 find_get_entry+0x5d/0x290 mm/filemap.c:2007
 filemap_get_folios_tag+0x136/0x230 mm/filemap.c:2305
 write_cache_pages+0x204/0x760 mm/page-writeback.c:2429
 do_writepages+0x212/0x340 mm/page-writeback.c:2556
 filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:390
 __filemap_fdatawrite_range mm/filemap.c:423 [inline]
 file_write_and_wait_range+0xfa/0x190 mm/filemap.c:781
 blkdev_fsync+0x39/0x80 block/fops.c:457
 vfs_fsync_range+0x10b/0x120 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2469 [inline]
 blkdev_write_iter+0x36d/0x3d0 block/fops.c:551
 do_iter_write+0x4ae/0x770 fs/read_write.c:860
 vfs_iter_write+0x50/0x70 fs/read_write.c:901
 iter_file_splice_write+0x456/0x7d0 fs/splice.c:795
 do_splice_from fs/splice.c:873 [inline]
 direct_splice_actor+0x84/0xa0 fs/splice.c:1039
 splice_direct_to_actor+0x2ee/0x5f0 fs/splice.c:994
 do_splice_direct+0x104/0x180 fs/splice.c:1082
 do_sendfile+0x3b8/0x950 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000000ffff0000 -> 0x00000000fff00000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 4406 Comm: syz-executor.2 Not tainted 6.4.0-rc4-syzkaller-00204-gc43a6ff9f93f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
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syz-executor.2 (4406) used greatest stack depth: 10392 bytes left