syzbot

==================================================================
BUG: KCSAN: data-race in xas_clear_mark / xas_find_marked

read-write to 0xffff88816b087fe0 of 8 bytes by task 10125 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_clear_bit include/asm-generic/bitops/instrumented-non-atomic.h:114 [inline]
 node_clear_mark lib/xarray.c:102 [inline]
 xas_clear_mark+0x99/0x190 lib/xarray.c:922
 __folio_start_writeback+0x2fc/0x440 mm/page-writeback.c:3115
 ext4_bio_write_folio+0x591/0x9d0 fs/ext4/page-io.c:583
 mpage_submit_folio fs/ext4/inode.c:1936 [inline]
 mpage_process_page_bufs+0x488/0x5d0 fs/ext4/inode.c:2049
 mpage_prepare_extent_to_map+0x791/0xb80 fs/ext4/inode.c:2550
 ext4_do_writepages+0x705/0x21d0 fs/ext4/inode.c:2691
 ext4_writepages+0x183/0x320 fs/ext4/inode.c:2828
 do_writepages+0x1d8/0x480 mm/page-writeback.c:2656
 filemap_fdatawrite_wbc mm/filemap.c:386 [inline]
 __filemap_fdatawrite_range mm/filemap.c:419 [inline]
 file_write_and_wait_range+0x16e/0x2f0 mm/filemap.c:794
 generic_buffers_fsync_noflush+0x46/0x120 fs/buffer.c:600
 ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
 ext4_sync_file+0x1c3/0x6c0 fs/ext4/fsync.c:147
 vfs_fsync_range+0x116/0x130 fs/sync.c:187
 generic_write_sync include/linux/fs.h:2976 [inline]
 ext4_buffered_write_iter+0x358/0x3c0 fs/ext4/file.c:305
 ext4_file_write_iter+0x3b2/0xf80 include/linux/fs.h:-1
 iter_file_splice_write+0x5f2/0x980 fs/splice.c:738
 do_splice_from fs/splice.c:935 [inline]
 direct_splice_actor+0x160/0x2c0 fs/splice.c:1158
 splice_direct_to_actor+0x305/0x680 fs/splice.c:1102
 do_splice_direct_actor fs/splice.c:1201 [inline]
 do_splice_direct+0xd9/0x150 fs/splice.c:1227
 do_sendfile+0x40a/0x690 fs/read_write.c:1368
 __do_sys_sendfile64 fs/read_write.c:1429 [inline]
 __se_sys_sendfile64 fs/read_write.c:1415 [inline]
 __x64_sys_sendfile64+0x113/0x160 fs/read_write.c:1415
 x64_sys_call+0xfc3/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88816b087fe0 of 8 bytes by task 10128 on cpu 0:
 xas_find_chunk include/linux/xarray.h:1746 [inline]
 xas_find_marked+0x21d/0x660 lib/xarray.c:1510
 find_get_entry+0x5d/0x370 mm/filemap.c:2027
 filemap_get_folios_tag+0xa0/0x220 mm/filemap.c:2294
 mpage_prepare_extent_to_map+0x332/0xb80 fs/ext4/inode.c:2452
 ext4_do_writepages+0x705/0x21d0 fs/ext4/inode.c:2691
 ext4_writepages+0x183/0x320 fs/ext4/inode.c:2828
 do_writepages+0x1d8/0x480 mm/page-writeback.c:2656
 filemap_fdatawrite_wbc mm/filemap.c:386 [inline]
 __filemap_fdatawrite_range mm/filemap.c:419 [inline]
 file_write_and_wait_range+0x16e/0x2f0 mm/filemap.c:794
 generic_buffers_fsync_noflush+0x46/0x120 fs/buffer.c:600
 ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
 ext4_sync_file+0x1c3/0x6c0 fs/ext4/fsync.c:147
 vfs_fsync_range+0x116/0x130 fs/sync.c:187
 generic_write_sync include/linux/fs.h:2976 [inline]
 ext4_buffered_write_iter+0x358/0x3c0 fs/ext4/file.c:305
 ext4_file_write_iter+0x3b2/0xf80 include/linux/fs.h:-1
 iter_file_splice_write+0x5f2/0x980 fs/splice.c:738
 do_splice_from fs/splice.c:935 [inline]
 direct_splice_actor+0x160/0x2c0 fs/splice.c:1158
 splice_direct_to_actor+0x305/0x680 fs/splice.c:1102
 do_splice_direct_actor fs/splice.c:1201 [inline]
 do_splice_direct+0xd9/0x150 fs/splice.c:1227
 do_sendfile+0x40a/0x690 fs/read_write.c:1368
 __do_sys_sendfile64 fs/read_write.c:1429 [inline]
 __se_sys_sendfile64 fs/read_write.c:1415 [inline]
 __x64_sys_sendfile64+0x113/0x160 fs/read_write.c:1415
 x64_sys_call+0xfc3/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000600 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 10128 Comm: syz.8.12856 Not tainted 6.14.0-syzkaller-13423-ga8662bcd2ff1 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
==================================================================