syzbot

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BUG: KCSAN: data-race in xas_find_marked / xas_set_mark

write to 0xffff8881057ff04c of 4 bytes by task 31206 on cpu 1:
 xa_mark_set lib/xarray.c:71 [inline]
 xas_set_mark+0x131/0x150 lib/xarray.c:892
 __folio_start_writeback+0x1f1/0x450 mm/page-writeback.c:3061
 ext4_bio_write_folio+0x592/0x9a0 fs/ext4/page-io.c:557
 mpage_submit_folio fs/ext4/inode.c:1869 [inline]
 mpage_process_page_bufs+0x488/0x5d0 fs/ext4/inode.c:1982
 mpage_prepare_extent_to_map+0x788/0xb80 fs/ext4/inode.c:2490
 ext4_do_writepages+0xa20/0x2110 fs/ext4/inode.c:2677
 ext4_writepages+0x159/0x2e0 fs/ext4/inode.c:2768
 do_writepages+0x1d8/0x480 mm/page-writeback.c:2612
 filemap_fdatawrite_wbc+0xdb/0x100 mm/filemap.c:397
 __filemap_fdatawrite_range mm/filemap.c:430 [inline]
 file_write_and_wait_range+0xc8/0x170 mm/filemap.c:788
 generic_buffers_fsync_noflush+0x4c/0x130 fs/buffer.c:602
 ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
 ext4_sync_file+0x20b/0x6c0 fs/ext4/fsync.c:151
 vfs_fsync_range+0x122/0x140 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2795 [inline]
 ext4_buffered_write_iter+0x338/0x380 fs/ext4/file.c:305
 ext4_file_write_iter+0x29f/0xe30
 call_write_iter include/linux/fs.h:2110 [inline]
 iter_file_splice_write+0x5e6/0x970 fs/splice.c:743
 do_splice_from fs/splice.c:941 [inline]
 direct_splice_actor+0x16c/0x2c0 fs/splice.c:1164
 splice_direct_to_actor+0x305/0x670 fs/splice.c:1108
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x3b9/0x970 fs/read_write.c:1295
 __do_sys_sendfile64 fs/read_write.c:1362 [inline]
 __se_sys_sendfile64 fs/read_write.c:1348 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
 x64_sys_call+0x2c67/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881057ff04c of 4 bytes by task 31180 on cpu 0:
 xa_marked include/linux/xarray.h:420 [inline]
 xas_find_marked+0x611/0x660 lib/xarray.c:1327
 find_get_entry+0x5d/0x290 mm/filemap.c:1968
 filemap_get_folios_tag+0x9e/0x210 mm/filemap.c:2218
 __filemap_fdatawait_range+0x82/0x140 mm/filemap.c:523
 filemap_fdatawait_range+0x26/0xf0 mm/filemap.c:559
 filemap_fdatawait include/linux/pagemap.h:46 [inline]
 __writeback_single_inode+0xf0/0x870 fs/fs-writeback.c:1660
 writeback_single_inode+0x12f/0x4a0 fs/fs-writeback.c:1771
 sync_inode_metadata+0x5c/0x90 fs/fs-writeback.c:2833
 generic_buffers_fsync_noflush+0xe4/0x130 fs/buffer.c:612
 ext4_fsync_nojournal fs/ext4/fsync.c:88 [inline]
 ext4_sync_file+0x20b/0x6c0 fs/ext4/fsync.c:151
 vfs_fsync_range+0x122/0x140 fs/sync.c:188
 generic_write_sync include/linux/fs.h:2795 [inline]
 ext4_buffered_write_iter+0x338/0x380 fs/ext4/file.c:305
 ext4_file_write_iter+0x29f/0xe30
 call_write_iter include/linux/fs.h:2110 [inline]
 iter_file_splice_write+0x5e6/0x970 fs/splice.c:743
 do_splice_from fs/splice.c:941 [inline]
 direct_splice_actor+0x16c/0x2c0 fs/splice.c:1164
 splice_direct_to_actor+0x305/0x670 fs/splice.c:1108
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x3b9/0x970 fs/read_write.c:1295
 __do_sys_sendfile64 fs/read_write.c:1362 [inline]
 __se_sys_sendfile64 fs/read_write.c:1348 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
 x64_sys_call+0x2c67/0x2d30 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x05000021 -> 0x02000021

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 31180 Comm: syz-executor.3 Tainted: G        W          6.9.0-rc6-syzkaller-00234-g7367539ad4b0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
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