syzbot has bisected this bug to: commit 9446e6fce0ab9dfd44b96f630b4e3a0a0ab879fd Author: Paolo Bonzini <pbonzini@xxxxxxxxxx> Date: Wed Feb 12 12:27:10 2020 +0000 KVM: x86: fix WARN_ON check of an unsigned less than zero bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1744891de00000 start commit: 5076190d mm: slub: be more careful about the double cmpxch.. git tree: upstream final crash: https://syzkaller.appspot.com/x/report.txt?x=14c4891de00000 console output: https://syzkaller.appspot.com/x/log.txt?x=10c4891de00000 kernel config: https://syzkaller.appspot.com/x/.config?x=9f894bd92023de02 dashboard link: https://syzkaller.appspot.com/bug?extid=00be5da1d75f1cc95f6b syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10bb4023e00000 Reported-by: syzbot+00be5da1d75f1cc95f6b@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: 9446e6fce0ab ("KVM: x86: fix WARN_ON check of an unsigned less than zero") For information about bisection process see: https://goo.gl/tpsmEJ#bisection