syzbot

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BUG: KCSAN: data-race in __xa_set_mark / filemap_write_and_wait_range

write to 0xffff88810734af04 of 4 bytes by task 18355 on cpu 0:
 xa_mark_set lib/xarray.c:71 [inline]
 xas_set_mark lib/xarray.c:900 [inline]
 __xa_set_mark+0x172/0x1a0 lib/xarray.c:2076
 __folio_mark_dirty+0x3af/0x4c0 mm/page-writeback.c:2767
 mark_buffer_dirty+0x11e/0x210 fs/buffer.c:1209
 block_commit_write fs/buffer.c:2222 [inline]
 block_write_end+0x12e/0x210 fs/buffer.c:2299
 ext4_write_end+0x13a/0x730 fs/ext4/inode.c:1309
 ext4_da_write_end+0x71/0x7b0 fs/ext4/inode.c:3079
 generic_perform_write+0x312/0x490 mm/filemap.c:4124
 ext4_buffered_write_iter+0x1ee/0x3c0 fs/ext4/file.c:299
 ext4_dio_write_iter fs/ext4/file.c:608 [inline]
 ext4_file_write_iter+0xdbf/0xf00 fs/ext4/file.c:716
 iter_file_splice_write+0x5f2/0x970 fs/splice.c:738
 do_splice_from fs/splice.c:935 [inline]
 direct_splice_actor+0x153/0x2a0 fs/splice.c:1158
 splice_direct_to_actor+0x30f/0x680 fs/splice.c:1102
 do_splice_direct_actor fs/splice.c:1201 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1227
 do_sendfile+0x380/0x640 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+0x105/0x150 fs/read_write.c:1415
 x64_sys_call+0xb39/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810734af04 of 4 bytes by task 18363 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:382 [inline]
 __filemap_fdatawrite_range mm/filemap.c:419 [inline]
 filemap_write_and_wait_range+0xfc/0x340 mm/filemap.c:691
 ext4_dio_write_iter fs/ext4/file.c:621 [inline]
 ext4_file_write_iter+0xe04/0xf00 fs/ext4/file.c:716
 iter_file_splice_write+0x5f2/0x970 fs/splice.c:738
 do_splice_from fs/splice.c:935 [inline]
 direct_splice_actor+0x153/0x2a0 fs/splice.c:1158
 splice_direct_to_actor+0x30f/0x680 fs/splice.c:1102
 do_splice_direct_actor fs/splice.c:1201 [inline]
 do_splice_direct+0xda/0x150 fs/splice.c:1227
 do_sendfile+0x380/0x640 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+0x105/0x150 fs/read_write.c:1415
 x64_sys_call+0xb39/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000021 -> 0x0a000021

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 18363 Comm: syz.9.3355 Not tainted 6.15.0-rc7-syzkaller-00002-gb36ddb9210e6 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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