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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: 906d, last: 5d13h
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
2025/08/27 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
2025/06/30 02:46 10m retest repro linux-5.15.y report log
2025/06/30 02:46 16m retest repro linux-5.15.y report log
2025/06/30 02:46 16m retest repro linux-5.15.y report log
2025/06/30 02:46 9m retest repro linux-5.15.y report log
2025/06/08 16:25 12m 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:
L1TF CPU bug present and SMT on, data leak possible. See CVE-2018-3646 and https://www.kernel.org/doc/html/latest/admin-guide/hw-vuln/l1tf.html for details.
=============================
WARNING: suspicious RCU usage
5.15.184-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-executor262/4166:
 #0: ffff88807d79c0c8 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0x1c8/0xb80 virt/kvm/kvm_main.c:3871

stack backtrace:
CPU: 1 PID: 4166 Comm: syz-executor262 Not tainted 5.15.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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_leave_nested+0x7e/0xc0 arch/x86/kvm/vmx/nested.c:6342
 kvm_leave_nested arch/x86/kvm/x86.c:618 [inline]
 kvm_vcpu_ioctl_x86_set_vcpu_events+0x95b/0x1190 arch/x86/kvm/x86.c:4812
 kvm_arch_vcpu_ioctl+0x1092/0x19d0 arch/x86/kvm/x86.c:5297
 kvm_vcpu_ioctl+0x6b1/0xb80 virt/kvm/kvm_main.c:4050
 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: 0033:0x7f1a949aa279
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 00 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffd9007ed88 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffd9007ef58 RCX: 00007f1a949aa279

Crashes (210):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
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
2025/08/10 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
2025/05/13 00:18 linux-5.15.y 3b8db0e4f263 f6671af7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/05/13 00:18 linux-5.15.y 3b8db0e4f263 f6671af7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/05/12 04:42 linux-5.15.y 3b8db0e4f263 77908e5f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/05/08 00:44 linux-5.15.y 16fdf2c7111b dbf35fa1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/05/05 08:36 linux-5.15.y 16fdf2c7111b b0714e37 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/05/01 22:25 linux-5.15.y f7347f400572 51b137cd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/04/25 01:58 linux-5.15.y f7347f400572 9882047a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/04/14 11:06 linux-5.15.y f7347f400572 0bd6db41 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/04/13 23:35 linux-5.15.y f7347f400572 0bd6db41 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/04/11 12:12 linux-5.15.y f7347f400572 94486846 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/03/19 22:52 linux-5.15.y 0c935c049b5c e20d7b13 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/03/18 11:45 linux-5.15.y 0c935c049b5c ce3352cd .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/02/25 21:25 linux-5.15.y c16c81c81336 d34966d1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/02/25 14:49 linux-5.15.y c16c81c81336 d34966d1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/02/22 02:53 linux-5.15.y c16c81c81336 d34966d1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/02/18 05:46 linux-5.15.y c16c81c81336 429ea007 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/02/12 21:58 linux-5.15.y c16c81c81336 b27c2402 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/02/12 21:56 linux-5.15.y c16c81c81336 b27c2402 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/02/12 07:05 linux-5.15.y c16c81c81336 f2baddf5 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/01/22 12:28 linux-5.15.y 4735586da88e da72ac06 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/01/17 23:31 linux-5.15.y 4735586da88e 953d1c45 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/01/17 22:04 linux-5.15.y 4735586da88e 953d1c45 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/01/06 05:02 linux-5.15.y 91786f140358 f3558dbf .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2025/01/02 23:46 linux-5.15.y 91786f140358 d3ccff63 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/12/15 11:43 linux-5.15.y 963e654022cc 7cbfbb3a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/12/14 05:43 linux-5.15.y 0a51d2d4527b 7cbfbb3a .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/11/02 01:05 linux-5.15.y 72244eab0dad f00eed24 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan WARNING: suspicious RCU usage in kvm_vcpu_memslots
2024/11/01 11:37 linux-5.15.y 72244eab0dad 96eb609f .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.