loop1: detected capacity change from 0 to 4096
EXT4-fs (loop1): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
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BUG: KCSAN: data-race in __xa_set_mark / xas_find_marked

write to 0xffff888100683c14 of 4 bytes by task 4277 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:2082
 __folio_mark_dirty+0x42c/0x520 mm/page-writeback.c:2689
 mark_buffer_dirty+0x120/0x1f0 fs/buffer.c:1116
 block_commit_write fs/buffer.c:2196 [inline]
 block_write_end+0x12d/0x210 fs/buffer.c:2272
 ext4_write_end+0x11b/0x6f0 fs/ext4/inode.c:1458
 ext4_da_write_end+0x67/0x7b0 fs/ext4/inode.c:3296
 generic_perform_write+0x314/0x490 mm/filemap.c:4357
 ext4_buffered_write_iter+0x2e2/0x480 fs/ext4/file.c:316
 ext4_file_write_iter+0x38e/0xef0 fs/ext4/file.c:-1
 iter_file_splice_write+0x6a0/0xa60 fs/splice.c:736
 do_splice_from fs/splice.c:936 [inline]
 direct_splice_actor+0x156/0x280 fs/splice.c:1159
 splice_direct_to_actor+0x2f9/0x680 fs/splice.c:1103
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x119/0x1a0 fs/splice.c:1228
 do_sendfile+0x37d/0x640 fs/read_write.c:1371
 __do_sys_sendfile64 fs/read_write.c:1432 [inline]
 __se_sys_sendfile64 fs/read_write.c:1418 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1418
 x64_sys_call+0x2dc4/0x3020 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888100683c14 of 4 bytes by task 4268 on cpu 1:
 xa_marked include/linux/xarray.h:424 [inline]
 xas_find_marked+0x602/0x650 lib/xarray.c:1483
 find_get_entry mm/filemap.c:2081 [inline]
 filemap_get_folios_tag+0xf7/0x400 mm/filemap.c:2349
 __filemap_fdatawait_range mm/filemap.c:524 [inline]
 filemap_fdatawait_range+0x88/0x1e0 mm/filemap.c:559
 filemap_fdatawait include/linux/pagemap.h:51 [inline]
 __writeback_single_inode+0xd6/0x660 fs/fs-writeback.c:1797
 writeback_single_inode+0x16d/0x400 fs/fs-writeback.c:1906
 sync_inode_metadata+0x6e/0xa0 fs/fs-writeback.c:3080
 mmb_fsync_noflush+0xfa/0x140 fs/buffer.c:663
 ext4_fsync_nojournal fs/ext4/fsync.c:92 [inline]
 ext4_sync_file+0x1f2/0x6d0 fs/ext4/fsync.c:160
 vfs_fsync_range+0xc5/0xe0 fs/sync.c:186
 generic_write_sync include/linux/fs.h:2666 [inline]
 ext4_buffered_write_iter+0x426/0x480 fs/ext4/file.c:322
 ext4_file_write_iter+0x38e/0xef0 fs/ext4/file.c:-1
 iter_file_splice_write+0x6a0/0xa60 fs/splice.c:736
 do_splice_from fs/splice.c:936 [inline]
 direct_splice_actor+0x156/0x280 fs/splice.c:1159
 splice_direct_to_actor+0x2f9/0x680 fs/splice.c:1103
 do_splice_direct_actor fs/splice.c:1202 [inline]
 do_splice_direct+0x119/0x1a0 fs/splice.c:1228
 do_sendfile+0x37d/0x640 fs/read_write.c:1371
 __do_sys_sendfile64 fs/read_write.c:1432 [inline]
 __se_sys_sendfile64 fs/read_write.c:1418 [inline]
 __x64_sys_sendfile64+0x105/0x150 fs/read_write.c:1418
 x64_sys_call+0x2dc4/0x3020 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 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: 4268 Comm: syz.1.214 Not tainted syzkaller #0 PREEMPT(lazy) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
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