syzbot


KCSAN: data-race in file_modified_flags / inode_update_timestamps

Status: moderation: reported on 2024/05/28 00:41
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+1d111dbd571bc392f537@syzkaller.appspotmail.com
First crash: 21d, last: 21d

Sample crash report:
bridge2: the hash_elasticity option has been deprecated and is always 16
Cannot find add_set index 0 as target
==================================================================
BUG: KCSAN: data-race in file_modified_flags / inode_update_timestamps

write to 0xffff888120230f48 of 8 bytes by task 21362 on cpu 1:
 inode_set_mtime_to_ts include/linux/fs.h:1587 [inline]
 inode_update_timestamps+0x16f/0x280 fs/inode.c:1865
 generic_update_time fs/inode.c:1900 [inline]
 inode_update_time fs/inode.c:1920 [inline]
 __file_update_time fs/inode.c:2109 [inline]
 file_modified_flags+0x2a7/0x340 fs/inode.c:2180
 file_modified+0x17/0x20 fs/inode.c:2196
 ext4_dio_write_checks fs/ext4/file.c:485 [inline]
 ext4_dio_write_iter fs/ext4/file.c:551 [inline]
 ext4_file_write_iter+0x8b8/0xe30 fs/ext4/file.c:696
 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+0x3ab/0x960 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+0x2c9f/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888120230f48 of 8 bytes by task 21358 on cpu 0:
 inode_get_mtime include/linux/fs.h:1581 [inline]
 inode_needs_update_time fs/inode.c:2088 [inline]
 file_modified_flags+0xe6/0x340 fs/inode.c:2174
 file_modified+0x17/0x20 fs/inode.c:2196
 ext4_dio_write_checks fs/ext4/file.c:485 [inline]
 ext4_dio_write_iter fs/ext4/file.c:551 [inline]
 ext4_file_write_iter+0x8b8/0xe30 fs/ext4/file.c:696
 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+0x3ab/0x960 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+0x2c9f/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000020947fee -> 0x00000000225e436e

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 21358 Comm: syz-executor.3 Tainted: G        W          6.10.0-rc1-syzkaller-00013-g2bfcfd584ff5 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
==================================================================

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/05/28 00:40 upstream 2bfcfd584ff5 f550015e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in file_modified_flags / inode_update_timestamps
* Struck through repros no longer work on HEAD.