syzbot


KCSAN: data-race in d_make_discardable / step_into_slowpath

Status: moderation: reported on 2025/12/08 04:14
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+a179b542833272197887@syzkaller.appspotmail.com
First crash: 49d, last: 20h47m

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

write to 0xffff88811acffe40 of 4 bytes by task 11972 on cpu 0:
 d_make_discardable+0x4f/0xa0 fs/dcache.c:936
 simple_unlink+0x68/0x80 fs/libfs.c:807
 shmem_unlink+0x12d/0x140 mm/shmem.c:3991
 vfs_unlink+0x28b/0x440 fs/namei.c:5378
 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 0xffff88811acffe40 of 4 bytes by task 3002 on cpu 1:
 __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: 0x08300080 -> 0x00004080

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3002 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 (32):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/01/25 22:16 upstream 023777797472 55756628 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2026/01/23 23:26 upstream 5bde837031a3 4f25b9b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2026/01/23 23:25 upstream 5bde837031a3 4f25b9b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2026/01/23 10:05 upstream c072629f05d7 e2b1b6e6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2026/01/23 04:42 upstream c072629f05d7 82c9c083 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2026/01/22 04:53 upstream cf38b2340c0e a16aed1d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2026/01/21 19:38 upstream cf38b2340c0e 8fc37797 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2026/01/21 16:22 upstream 6c790212c588 8fc37797 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2026/01/19 09:07 upstream 24d479d26b25 a9fc5226 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2026/01/18 02:42 upstream d12453c7e281 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2026/01/16 23:40 upstream b62ce2547fe8 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2026/01/16 23:40 upstream b62ce2547fe8 20d37d28 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2026/01/15 10:42 upstream 944aacb68baf d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2026/01/12 14:31 upstream 0f61b1860cc3 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2026/01/11 11:31 upstream 755bc1335e3b d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2026/01/10 22:06 upstream 97313d6113ab d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2026/01/09 06:02 upstream 623fb9912f6a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2026/01/06 19:34 upstream f0b9d8eb98df d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2026/01/05 23:53 upstream 7f98ab9da046 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2026/01/02 18:45 upstream 9b0436804460 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2025/12/31 21:03 upstream 349bd28a86f2 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2025/12/30 17:40 upstream dbf8fe85a16a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2025/12/22 13:15 upstream 9448598b22c5 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2025/12/21 08:02 upstream 9094662f6707 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2025/12/20 18:46 upstream d8ba32c5a460 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2025/12/16 08:58 upstream 40fbbd64bba6 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2025/12/16 08:57 upstream 40fbbd64bba6 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2025/12/13 04:42 upstream 9551a26f17d9 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2025/12/12 10:53 upstream 187d0801404f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2025/12/10 08:26 upstream c9b47175e913 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2025/12/09 05:30 upstream cfd4039213e7 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
2025/12/08 04:13 upstream ba65a4e7120a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / step_into_slowpath
* Struck through repros no longer work on HEAD.