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BUG: KCSAN: data-race in xas_clear_mark / xas_find_marked

read-write to 0xffff888106607b50 of 8 bytes by task 3994 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]
 filemap_write_and_wait_range+0x152/0x370 mm/filemap.c:691
 ext4_insert_range+0x1c5/0x670 fs/ext4/extents.c:5409
 ext4_fallocate+0x37f/0x690 fs/ext4/extents.c:4770
 vfs_fallocate+0x368/0x3b0 fs/open.c:338
 ksys_fallocate fs/open.c:362 [inline]
 __do_sys_fallocate fs/open.c:367 [inline]
 __se_sys_fallocate fs/open.c:365 [inline]
 __x64_sys_fallocate+0x78/0xc0 fs/open.c:365
 x64_sys_call+0x295f/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:286
 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 0xffff888106607b50 of 8 bytes by task 3979 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+0x13e/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
 new_sync_write fs/read_write.c:591 [inline]
 vfs_write+0x79b/0x950 fs/read_write.c:684
 ksys_pwrite64 fs/read_write.c:791 [inline]
 __do_sys_pwrite64 fs/read_write.c:799 [inline]
 __se_sys_pwrite64 fs/read_write.c:796 [inline]
 __x64_sys_pwrite64+0xfb/0x150 fs/read_write.c:796
 x64_sys_call+0xab9/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:19
 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: 0x00000000fe000000 -> 0x00000000c0000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3979 Comm: syz.0.168 Not tainted 6.14.0-syzkaller-13389-ga52a3c18cdf3 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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