syzbot


KCSAN: data-race in atime_needs_update / ext4_punch_hole

Status: auto-closed as invalid on 2021/12/18 19:09
Reported-by: syzbot+@syzkaller.appspotmail.com
First crash: 386d, last: 386d

Sample crash report:
==================================================================
BUG: KCSAN: data-race in atime_needs_update / ext4_punch_hole

write to 0xffff88813c715bf8 of 8 bytes by task 31820 on cpu 0:
 ext4_punch_hole+0x7c1/0xa20 fs/ext4/inode.c:4064
 ext4_fallocate+0xea/0x540 fs/ext4/extents.c:4703
 vfs_fallocate+0x486/0x720 fs/open.c:307
 ksys_fallocate fs/open.c:330 [inline]
 __do_sys_fallocate fs/open.c:338 [inline]
 __se_sys_fallocate fs/open.c:336 [inline]
 __x64_sys_fallocate+0x75/0xc0 fs/open.c:336
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88813c715bf8 of 8 bytes by task 31817 on cpu 1:
 timespec64_compare include/linux/time64.h:60 [inline]
 relatime_need_update fs/inode.c:1748 [inline]
 atime_needs_update+0x34b/0x390 fs/inode.c:1836
 touch_atime+0x63/0x2e0 fs/inode.c:1851
 file_accessed include/linux/fs.h:2505 [inline]
 generic_file_splice_read+0x2a9/0x330 fs/splice.c:314
 do_splice_to fs/splice.c:796 [inline]
 splice_direct_to_actor+0x2aa/0x650 fs/splice.c:870
 do_splice_direct+0x106/0x190 fs/splice.c:979
 do_sendfile+0x675/0xc40 fs/read_write.c:1245
 __do_sys_sendfile64 fs/read_write.c:1310 [inline]
 __se_sys_sendfile64 fs/read_write.c:1296 [inline]
 __x64_sys_sendfile64+0x102/0x140 fs/read_write.c:1296
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x000000000c743e9b -> 0x000000000d0cd51b

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 31817 Comm: syz-executor.5 Not tainted 5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================

Crashes (1):
Manager Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Title
ci2-upstream-kcsan-gce 2021/11/13 19:08 upstream 66f4beaa6c1d 75b04091 .config log report info KCSAN: data-race in atime_needs_update / ext4_punch_hole
* Struck through repros no longer work on HEAD.