[syzbot] WARNING: suspicious RCU usage (5)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: a5b00f5b78b7 Merge branch 'hns3-fixres'
git tree: net
console output: https://syzkaller.appspot.com/x/log.txt?x=105d68bbf00000
kernel config: https://syzkaller.appspot.com/x/.config?x=20ac3e0ebf0db3bd
dashboard link: https://syzkaller.appspot.com/bug?extid=9cbc6bed3a22f1d37395
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=143b22abf00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=125194eff00000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+9cbc6b...@syzkaller.appspotmail.com

netdevsim netdevsim0 netdevsim0: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim1: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim2: set [1, 0] type 2 family 0 port 6081 - 0
netdevsim netdevsim0 netdevsim3: set [1, 0] type 2 family 0 port 6081 - 0
=============================
WARNING: suspicious RCU usage
5.19.0-rc1-syzkaller-00254-ga5b00f5b78b7 #0 Not tainted
-----------------------------
net/ipv6/addrconf


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[syzbot]

syzbot has bisected this issue to:

commit c2ff53d8049f30098153cd2d1299a44d7b124c57
Author: Xuan Zhuo <xuan...@linux.alibaba.com>
Date: Thu Feb 18 20:50:02 2021 +0000

net: Add priv_flags for allow tx skb without linear

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=11596838080000
start commit: a5b00f5b78b7 Merge branch 'hns3-fixres'
git tree: net
final oops: https://syzkaller.appspot.com/x/report.txt?x=13596838080000
console output: https://syzkaller.appspot.com/x/log.txt?x=15596838080000

kernel config: https://syzkaller.appspot.com/x/.config?x=20ac3e0ebf0db3bd
dashboard link: https://syzkaller.appspot.com/bug?extid=9cbc6bed3a22f1d37395

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=143b22abf00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=125194eff00000

Reported-by: syzbot+9cbc6b...@syzkaller.appspotmail.com
Fixes: c2ff53d8049f ("net: Add priv_flags for allow tx skb without linear")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection

[Xuan Zhuo]

I think it's unlikely that my patch is causing the problem, because my patch is
very simple and doesn't have any effect on the kernel. I don't know if there is
something wrong.

I used the above config (make olddefconfig) to compile this commit, and it
crashed directly after starting it in qemu.

Thanks.

[Paolo Bonzini]

#syz fix: x86/kvm: Fix broken irq restoration in kvm_wait