syzbot


KCSAN: data-race in d_make_discardable / lookup_fast

Status: moderation: reported on 2025/12/08 15:40
Subsystems: fs
Labels: prio:low
[Documentation on labels]
Reported-by: syzbot+7184882226c848d0286e@syzkaller.appspotmail.com
First crash: 176d, last: 1d10h
✨ AI Jobs (2)
ID Workflow Result Correct Bug Created Started Finished Revision Error
bfe82fe5-0934-4741-a408-09217c2cbe73 assessment-security DenialOfService: ❌ Exploitable: ❌ FilesystemTrigger: ❌ NetworkTrigger: ❌ PeripheralTrigger: ❌ RemoteTrigger: ❌ Unprivileged: ✅ UserNamespace: ✅ VMGuestTrigger: ❌ VMHostTrigger: ❌ KCSAN: data-race in d_make_discardable / lookup_fast 2026/05/25 04:04 2026/05/25 04:04 2026/05/25 05:12 c69befb30ac10e158cc9d1557b508ee3f0eca1de
8987d006-bba7-48f2-8ec7-4727f753efdc assessment-kcsan Benign: ✅ Confident: ✅ KCSAN: data-race in d_make_discardable / lookup_fast 2026/01/15 17:01 2026/01/15 17:01 2026/01/15 17:25 a9d6a79219801d2130df3b1a792c57f0e5428e9f

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

write to 0xffff8881004bb9c0 of 4 bytes by task 3287 on cpu 0:
 d_make_discardable+0x4f/0xa0 fs/dcache.c:984
 simple_unlink+0x68/0x80 fs/libfs.c:808
 shmem_unlink+0x12d/0x140 mm/shmem.c:3981
 vfs_unlink+0x1c7/0x490 fs/namei.c:5498
 filename_unlinkat+0x1e2/0x410 fs/namei.c:5568
 __do_sys_unlink fs/namei.c:5603 [inline]
 __se_sys_unlink+0x2b/0xe0 fs/namei.c:5600
 __x64_sys_unlink+0x1f/0x30 fs/namei.c:5600
 x64_sys_call+0x2eb6/0x3020 arch/x86/include/generated/asm/syscalls_64.h:88
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881004bb9c0 of 4 bytes by task 2982 on cpu 1:
 d_revalidate fs/namei.c:1029 [inline]
 lookup_fast+0xf0/0x320 fs/namei.c:1863
 walk_component fs/namei.c:2274 [inline]
 lookup_last fs/namei.c:2785 [inline]
 path_lookupat+0x15c/0x500 fs/namei.c:2809
 filename_lookup+0x190/0x390 fs/namei.c:2838
 do_readlinkat+0x74/0x2f0 fs/stat.c:571
 __do_sys_readlink fs/stat.c:605 [inline]
 __se_sys_readlink fs/stat.c:602 [inline]
 __x64_sys_readlink+0x47/0x60 fs/stat.c:602
 x64_sys_call+0x2b51/0x3020 arch/x86/include/generated/asm/syscalls_64.h:90
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x3b0 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: 2982 Comm: udevd Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
==================================================================

Crashes (96):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/06/02 03:45 upstream 6f3ed7fec72f 1095583b .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/06/01 02:51 upstream e43ffb69e043 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/05/31 13:01 upstream 174914ea5513 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/05/31 00:23 upstream 9d87d0fc8c8e 6b4a8443 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/05/26 20:49 upstream d60ec36cab33 2b01f00e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/05/24 20:59 upstream 6a97c4d5262d c69befb3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/05/22 14:53 upstream 45255ea1ca09 5f091fcc .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/05/21 17:09 upstream 758c807bb943 e195359d .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/05/20 16:15 upstream df685633c3db 62fb93a2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/05/16 21:13 upstream 6916d5703ddf de5aae85 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/05/14 17:39 upstream 66182ca873a4 6ccb967e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/05/07 13:49 upstream 8ab992f815d6 cbf9e0fc .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/05/04 07:07 upstream 6d35786de281 a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/05/03 17:40 upstream f377d0025eb0 a0d91488 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/05/01 03:18 upstream 26fd6bff2c05 753c55b9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/05/01 03:18 upstream 26fd6bff2c05 753c55b9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/04/28 20:20 upstream dca922e019dd 95008c03 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/04/28 02:19 upstream 3b3bea6d4b9c ce741359 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/04/27 20:58 upstream 254f49634ee1 ce741359 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/04/27 09:46 upstream 254f49634ee1 0f700595 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/04/26 20:11 upstream 20b64cf8705a 9c2d0995 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/04/24 13:27 upstream dd6c438c3e64 1c2b9291 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/04/22 23:07 upstream 2a4c0c11c019 b10da5ec .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/04/20 14:04 upstream c1f49dea2b8f e65da4ee .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/04/18 20:45 upstream eb5249b12507 303e2802 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/04/18 04:35 upstream 8541d8f725c6 5be7a9de .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/04/12 23:50 upstream 028ef9c96e96 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/04/10 05:50 upstream 9a9c8ce300cd 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/04/09 16:14 upstream 8b02520ec5f7 38c8e246 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/04/08 13:16 upstream 3036cd0d3328 d9b7f621 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/04/06 07:07 upstream 591cd656a1bf 4440e7c2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/04/02 10:02 upstream 9147566d8016 91bc79b0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/04/01 17:56 upstream dbf00d8d23b4 9a1f7828 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/03/30 22:36 upstream d0c3bcd5b897 d0af506e .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/03/29 17:51 upstream a3d97d1d3fa6 b5ceaad2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/03/25 22:43 upstream d2a43e7f89da c6143aac .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/03/24 21:53 upstream 24f9515de877 74e70d19 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/03/23 11:44 upstream c369299895a5 4933dba2 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/03/19 11:31 upstream 8a30aeb0d1b4 bd6dcb30 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/03/17 19:51 upstream 2d1373e4246d c8810548 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/03/12 06:28 upstream 80234b5ab240 2d88ab01 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/03/11 15:19 upstream b29fb8829bff 2d88ab01 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/03/09 13:10 upstream 1f318b96cc84 176bead5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/03/09 07:18 upstream 1f318b96cc84 5cb44a80 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/03/07 13:49 upstream 4ae12d8bd9a8 5cb44a80 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/03/06 02:06 upstream 5ee8dbf54602 31e9c887 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/03/02 09:51 upstream 11439c4635ed 43249bac .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/02/27 14:29 upstream a75cb869a8cc a2f13f71 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2026/01/15 10:40 upstream 944aacb68baf d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2025/12/12 10:55 upstream 187d0801404f d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
2025/12/08 15:39 upstream c2f2b01b74be d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-kcsan-gce KCSAN: data-race in d_make_discardable / lookup_fast
* Struck through repros no longer work on HEAD.