syzbot

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BUG: KCSAN: data-race in xas_clear_mark / xas_find_marked

read-write to 0xffff888126faf478 of 8 bytes by task 10533 on cpu 0:
 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_clear_bit include/asm-generic/bitops/instrumented-non-atomic.h:114 [inline]
 node_clear_mark lib/xarray.c:102 [inline]
 xas_clear_mark+0x8c/0x180 lib/xarray.c:914
 __folio_start_writeback+0x347/0x4b0 mm/page-writeback.c:3031
 ext4_bio_write_folio+0x592/0x9a0 fs/ext4/page-io.c:557
 mpage_submit_folio fs/ext4/inode.c:1865 [inline]
 mpage_map_and_submit_buffers fs/ext4/inode.c:2111 [inline]
 mpage_map_and_submit_extent fs/ext4/inode.c:2250 [inline]
 ext4_do_writepages+0x139f/0x2100 fs/ext4/inode.c:2675
 ext4_writepages+0x15e/0x2e0 fs/ext4/inode.c:2764
 do_writepages+0x1c2/0x340 mm/page-writeback.c:2553
 filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:390
 __filemap_fdatawrite_range mm/filemap.c:423 [inline]
 filemap_write_and_wait_range+0xe0/0x210 mm/filemap.c:678
 filemap_write_and_wait include/linux/pagemap.h:64 [inline]
 ext4_ioctl_setflags fs/ext4/ioctl.c:635 [inline]
 ext4_fileattr_set+0x57f/0xdd0 fs/ext4/ioctl.c:1012
 vfs_fileattr_set+0x596/0x5e0 fs/ioctl.c:697
 do_vfs_ioctl+0x10b2/0x13a0
 __do_sys_ioctl fs/ioctl.c:869 [inline]
 __se_sys_ioctl+0x81/0x140 fs/ioctl.c:857
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:857
 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 0xffff888126faf478 of 8 bytes by task 10528 on cpu 1:
 xas_find_chunk include/linux/xarray.h:1723 [inline]
 xas_find_marked+0x216/0x660 lib/xarray.c:1354
 find_get_entry+0x5d/0x290 mm/filemap.c:1978
 filemap_get_folios_tag+0xa2/0x250 mm/filemap.c:2266
 mpage_prepare_extent_to_map+0x321/0xb70 fs/ext4/inode.c:2388
 ext4_do_writepages+0xa20/0x2100 fs/ext4/inode.c:2673
 ext4_writepages+0x15e/0x2e0 fs/ext4/inode.c:2764
 do_writepages+0x1c2/0x340 mm/page-writeback.c:2553
 filemap_fdatawrite_wbc+0xdb/0xf0 mm/filemap.c:390
 __filemap_fdatawrite_range mm/filemap.c:423 [inline]
 file_write_and_wait_range+0xf4/0x190 mm/filemap.c:781
 ext4_sync_file+0x133/0x6c0 fs/ext4/fsync.c:158
 vfs_fsync_range+0x111/0x120 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2584 [inline]
 ext4_buffered_write_iter+0x334/0x370 fs/ext4/file.c:305
 ext4_file_write_iter+0xd6/0x1200
 call_write_iter include/linux/fs.h:1956 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x4ab/0x7d0 fs/read_write.c:584
 ksys_write+0xeb/0x1a0 fs/read_write.c:637
 __do_sys_write fs/read_write.c:649 [inline]
 __se_sys_write fs/read_write.c:646 [inline]
 __x64_sys_write+0x42/0x50 fs/read_write.c:646
 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: 0xffffffffffffff80 -> 0xfffffffffffffe00

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 10528 Comm: syz-executor.5 Not tainted 6.6.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
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syz-executor.5 (10528) used greatest stack depth: 10272 bytes left