syzbot


KCSAN: data-race in d_delete / step_into_slowpath

Status: moderation: reported on 2025/12/04 05:22
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+b33915cb4c9e1c5692ec@syzkaller.appspotmail.com
First crash: 49d, last: 2h45m

Sample crash report:
==================================================================
BUG: KCSAN: data-race in d_delete / step_into_slowpath

read-write to 0xffff88811b8e0240 of 4 bytes by task 4789 on cpu 1:
 d_delete+0x15a/0x180 fs/dcache.c:2519
 d_delete_notify+0x32/0x100 include/linux/fsnotify.h:375
 vfs_unlink+0x32c/0x440 fs/namei.c:5393
 do_unlinkat+0x1e2/0x4b0 fs/namei.c:5448
 __do_sys_unlink fs/namei.c:5483 [inline]
 __se_sys_unlink fs/namei.c:5481 [inline]
 __x64_sys_unlink+0x2e/0x40 fs/namei.c:5481
 x64_sys_call+0x2f48/0x3000 arch/x86/include/generated/asm/syscalls_64.h:88
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88811b8e0240 of 4 bytes by task 3006 on cpu 0:
 __d_entry_type include/linux/dcache.h:416 [inline]
 d_is_symlink include/linux/dcache.h:446 [inline]
 step_into_slowpath+0x139/0x4c0 fs/namei.c:2055
 step_into fs/namei.c:2099 [inline]
 walk_component fs/namei.c:2235 [inline]
 lookup_last fs/namei.c:2730 [inline]
 path_lookupat+0x330/0x500 fs/namei.c:2754
 filename_lookup+0x190/0x390 fs/namei.c:2783
 do_readlinkat+0x7d/0x340 fs/stat.c:576
 __do_sys_readlink fs/stat.c:613 [inline]
 __se_sys_readlink fs/stat.c:610 [inline]
 __x64_sys_readlink+0x47/0x60 fs/stat.c:610
 x64_sys_call+0x2af1/0x3000 arch/x86/include/generated/asm/syscalls_64.h:90
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00300180 -> 0x00004080

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3006 Comm: udevd Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================

Crashes (20):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/22 21:52 upstream a66191c590b3 82c9c083 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
2026/01/19 06:40 upstream 24d479d26b25 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
2026/01/16 11:23 upstream 603c05a1639f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
2026/01/15 14:27 upstream 944aacb68baf d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
2026/01/14 13:58 upstream c537e12daeec d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
2026/01/12 21:43 upstream 0f61b1860cc3 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
2026/01/10 06:55 upstream 372800cb95a3 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
2026/01/09 15:51 upstream 623fb9912f6a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
2026/01/06 14:13 upstream 7f98ab9da046 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
2025/12/31 15:51 upstream c8ebd433459b d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
2025/12/30 01:22 upstream 8640b74557fc d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
2025/12/29 05:48 upstream c875a6c32467 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
2025/12/25 16:00 upstream ccd1cdca5cd4 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
2025/12/23 07:08 upstream b927546677c8 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
2025/12/22 02:27 upstream 765b233a9b94 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
2025/12/11 01:06 upstream 0048fbb4011e d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
2025/12/10 01:10 upstream cb015814f8b6 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
2025/12/08 05:21 upstream ba65a4e7120a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
2025/12/06 00:06 upstream d1d36025a617 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
2025/12/04 05:21 upstream 8f7aa3d3c732 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_delete / step_into_slowpath
* Struck through repros no longer work on HEAD.