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WARNING: suspicious RCU usage in kvm_vcpu_memslots

Status: upstream: reported C repro on 2023/03/10 11:13
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+a703fc5de924fa2e1ae8@syzkaller.appspotmail.com
First crash: 1003d, last: 22h01m
Fix bisection: the issue occurs on the latest tested release (bisect log)
Crash: WARNING: suspicious RCU usage in kvm_vcpu_gfn_to_memslot (log)
Repro: C syz .config
  
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2023/05/05 linux-5.15.y (ToT) 8a7f2a5c5aa1 C [report] WARNING: suspicious RCU usage in kvm_vcpu_memslots
2023/05/05 upstream (ToT) 78b421b6a7c6 C Didn't crash
▶ ▼ Last patch testing requests (10)
Created Duration User Patch Repo Result
2025/11/27 17:52 12m retest repro linux-5.15.y report log
2025/11/27 17:52 11m retest repro linux-5.15.y report log
2025/11/27 17:52 10m retest repro linux-5.15.y report log
2025/11/27 17:52 9m retest repro linux-5.15.y report log
2025/11/27 17:52 9m retest repro linux-5.15.y report log
2025/08/27 07:17 10m retest repro linux-5.15.y report log
2025/08/27 07:17 46m retest repro linux-5.15.y report log
2025/08/27 07:17 10m retest repro linux-5.15.y report log
2025/08/27 07:17 10m retest repro linux-5.15.y report log
2025/08/27 07:17 10m retest repro linux-5.15.y report log
▶ ▼ Fix bisection attempts (3)
Created Duration User Patch Repo Result
2023/09/15 12:26 1h55m fix candidate upstream OK (0) job log
2023/06/18 19:09 34m bisect fix linux-5.15.y OK (0) job log log
2023/04/29 00:11 34m bisect fix linux-5.15.y OK (0) job log log

Sample crash report:
=============================
WARNING: suspicious RCU usage
syzkaller #0 Not tainted
-----------------------------
include/linux/kvm_host.h:889 suspicious rcu_dereference_check() usage!

other info that might help us debug this:


rcu_scheduler_active = 2, debug_locks = 1
1 lock held by syz.0.17/4323:
 #0: ffff88807e9680c8 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0x1c8/0xb80 virt/kvm/kvm_main.c:3871

stack backtrace:
CPU: 0 PID: 4323 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 __kvm_memslots include/linux/kvm_host.h:887 [inline]
 kvm_vcpu_memslots+0x1b6/0x200 include/linux/kvm_host.h:901
 kvm_vcpu_gfn_to_memslot+0x2b/0x3c0 virt/kvm/kvm_main.c:2158
 kvm_vcpu_unmap+0x5b/0x80 virt/kvm/kvm_main.c:2773
 nested_vmx_vmexit+0x13f5/0x28d0 arch/x86/kvm/vmx/nested.c:4676
 vmx_check_nested_events+0x7db/0x2370 arch/x86/kvm/vmx/nested.c:-1
 kvm_apic_accept_events+0x130/0x550 arch/x86/kvm/lapic.c:2914
 kvm_arch_vcpu_ioctl_get_mpstate+0x57/0x1b0 arch/x86/kvm/x86.c:10590
 kvm_vcpu_ioctl+0x54e/0xb80 virt/kvm/kvm_main.c:3956
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f5716e1bbe9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f5716449038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f5717053180 RCX: 00007f5716e1bbe9
RDX: 0000000000000000 RSI: 000000008004ae98 RDI: 0000000000000005
RBP: 00007f5716e9ee19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f5717053218 R14: 00007f5717053180 R15: 00007fff8124ae88
 </TASK>

Crashes (250):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/09/05 03:16 linux-5.15.y 7a6c2d093c45 d291dd2d .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/05/25 13:00 linux-5.15.y 98f47d0e9b8c ed351ea7 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/02/12 08:12 linux-5.15.y c16c81c81336 f2baddf5 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/11/02 08:07 linux-5.15.y 72244eab0dad f00eed24 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/07/21 09:23 linux-5.15.y 7c6d66f0266f b88348e9 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/04/27 10:23 linux-5.15.y c52b9710c83d 07b455f9 .config console log report syz C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/01/11 20:14 linux-5.15.y 26c690eff0a5 00f3cc59 .config console log report syz C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2023/08/29 10:32 linux-5.15.y 5ddfe5cc8716 7ba13a15 .config console log report syz C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2023/05/19 03:19 linux-5.15.y 9d6bde853685 3bb7af1d .config console log report syz C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2023/03/26 04:43 linux-5.15.y 115472395b0a fbf0499a .config console log report syz C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/12/07 12:57 linux-5.15.y 68efe5a6c16a d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/12/06 07:03 linux-5.15.y cc5ec8769306 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/12/05 03:59 linux-5.15.y cc5ec8769306 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/11/30 15:28 linux-5.15.y cc5ec8769306 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/11/29 21:18 linux-5.15.y cc5ec8769306 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/11/29 01:17 linux-5.15.y cc5ec8769306 d6526ea3 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/11/13 10:26 linux-5.15.y cc5ec8769306 07e030de .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/11/13 05:35 linux-5.15.y cc5ec8769306 07e030de .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/11/13 03:32 linux-5.15.y cc5ec8769306 07e030de .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/11/08 03:19 linux-5.15.y cc5ec8769306 4e1406b4 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/11/06 15:03 linux-5.15.y cc5ec8769306 a6c9c731 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/11/03 13:43 linux-5.15.y cc5ec8769306 2c50b6a9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/11/02 20:58 linux-5.15.y cc5ec8769306 2c50b6a9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/10/29 19:11 linux-5.15.y cc5ec8769306 fd2207e7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/10/28 20:12 linux-5.15.y ac56c046adf4 fd2207e7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/10/27 17:40 linux-5.15.y ac56c046adf4 fd2207e7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/10/24 01:03 linux-5.15.y ac56c046adf4 c0460fcd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/10/19 20:18 linux-5.15.y ac56c046adf4 1c8c8cd8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/10/13 18:27 linux-5.15.y 29e53a5b1c4f b6605ba8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/10/07 04:27 linux-5.15.y 29e53a5b1c4f 8ef35d49 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/10/04 00:10 linux-5.15.y 29e53a5b1c4f 49379ee0 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/09/24 00:55 linux-5.15.y 43bb85222e53 e667a34f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/09/19 18:10 linux-5.15.y 43bb85222e53 67c37560 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/09/16 03:14 linux-5.15.y 43bb85222e53 e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/09/14 18:21 linux-5.15.y 43bb85222e53 e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/09/14 18:19 linux-5.15.y 43bb85222e53 e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/09/12 02:17 linux-5.15.y 43bb85222e53 e2beed91 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/09/11 03:49 linux-5.15.y de9476bb4f1b fdeaa69b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/09/08 13:03 linux-5.15.y 7a6c2d093c45 d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/09/07 04:01 linux-5.15.y 7a6c2d093c45 d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/09/04 23:14 linux-5.15.y 7a6c2d093c45 d291dd2d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/08/10 00:26 linux-5.15.y c79648372d02 32a0e5ed .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/08/05 17:35 linux-5.15.y c79648372d02 37880f40 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/07/24 19:47 linux-5.15.y c79648372d02 65d60d73 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/07/24 06:58 linux-5.15.y c79648372d02 0c1d6ded .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/07/22 12:10 linux-5.15.y c79648372d02 1555463b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/07/20 14:21 linux-5.15.y c79648372d02 7117feec .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/07/19 05:12 linux-5.15.y c79648372d02 7117feec .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/07/19 00:50 linux-5.15.y c79648372d02 7117feec .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/07/18 17:39 linux-5.15.y c79648372d02 88248e14 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/07/18 06:38 linux-5.15.y c79648372d02 88248e14 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/07/16 03:55 linux-5.15.y 89950c454265 03fcfc4b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/07/15 19:59 linux-5.15.y 89950c454265 03fcfc4b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/06/30 22:08 linux-5.15.y 3dea0e7f549e 6e83b42d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/06/14 22:30 linux-5.15.y 1c700860e8bc 5f4b362d .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/06/13 01:32 linux-5.15.y 1c700860e8bc 98683f8f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/06/10 20:19 linux-5.15.y 1c700860e8bc 5d7e17ca .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/05/25 12:36 linux-5.15.y 98f47d0e9b8c ed351ea7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/05/15 08:16 linux-5.15.y 3b8db0e4f263 d6b2ee52 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2023/03/10 11:13 linux-5.15.y abddfcf701a5 5205ef30 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
* Struck through repros no longer work on HEAD.