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BUG: KCSAN: data-race in filemap_write_and_wait_range / xas_set_mark

write to 0xffff88811b8fab24 of 4 bytes by task 11071 on cpu 0:
 xa_mark_set lib/xarray.c:71 [inline]
 xas_set_mark+0x13d/0x150 lib/xarray.c:899
 tag_pages_for_writeback+0xa7/0x2a0 mm/page-writeback.c:2424
 ext4_do_writepages+0x696/0x2130 fs/ext4/inode.c:2671
 ext4_writepages+0x15c/0x2f0 fs/ext4/inode.c:2824
 do_writepages+0x1d8/0x480 mm/page-writeback.c:2687
 filemap_fdatawrite_wbc mm/filemap.c:389 [inline]
 __filemap_fdatawrite_range mm/filemap.c:422 [inline]
 file_write_and_wait_range+0x16e/0x2f0 mm/filemap.c:797
 generic_buffers_fsync_noflush+0x46/0x120 fs/buffer.c:600
 ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
 ext4_sync_file+0x1ff/0x6c0 fs/ext4/fsync.c:151
 vfs_fsync_range+0x116/0x130 fs/sync.c:187
 generic_write_sync include/linux/fs.h:2968 [inline]
 ext4_buffered_write_iter+0x358/0x3c0 fs/ext4/file.c:305
 ext4_dio_write_iter fs/ext4/file.c:608 [inline]
 ext4_file_write_iter+0xe26/0xf60 fs/ext4/file.c:715
 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 0xffff88811b8fab24 of 4 bytes by task 11077 on cpu 1:
 xa_marked include/linux/xarray.h:424 [inline]
 mapping_tagged include/linux/fs.h:540 [inline]
 filemap_fdatawrite_wbc mm/filemap.c:385 [inline]
 __filemap_fdatawrite_range mm/filemap.c:422 [inline]
 filemap_write_and_wait_range+0x105/0x370 mm/filemap.c:694
 ext4_dio_write_iter fs/ext4/file.c:621 [inline]
 ext4_file_write_iter+0xe69/0xf60 fs/ext4/file.c:715
 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: 0x02000021 -> 0x04000021

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 11077 Comm: syz.0.2439 Not tainted 6.14.0-syzkaller-05877-g1a9239bb4253 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
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