linux-kernel - Re: [PATCH V3 0/7] x86/entry: Convert error

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Message-ID: <34998a4c-7c58-295a-c216-7d217fee47d1@oracle.com>
Date:   Thu, 9 Jun 2022 12:43:39 +0200
From:   Vegard Nossum <vegard.nossum@...cle.com>
To:     Lai Jiangshan <jiangshanlai@...il.com>,
        linux-kernel@...r.kernel.org
Cc:     Borislav Petkov <bp@...en8.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Andy Lutomirski <luto@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>, x86@...nel.org,
        Lai Jiangshan <jiangshan.ljs@...group.com>
Subject: Re: [PATCH V3 0/7] x86/entry: Convert error_entry() to C code

On 6/9/22 11:11, Vegard Nossum wrote:
> On 6/6/22 16:45, Lai Jiangshan wrote:
>> From: Lai Jiangshan <jiangshan.ljs@...group.com>
>>
>> Add some C equivalent functions of the ASM macros and implement the whole
>> error_entry() as C code.
> 
> Hi,
> 
> I did some testing of your patches (on top of mainline commit
> 34f4335c16a5) and I see these two KASAN reports very occasionally during
> boot:
> 
> 1)
> 
> Mountpoint-cache hash table entries: 2048 (order: 2, 16384 bytes, linear)
> ==================================================================
> BUG: KASAN: wild-memory-access in rcu_nmi_enter+0x6e/0xf0

So this one I get without your patches as well. It's only about 1% of
boots, though. Let me try to bisect this and start a new thread.

> 2)
>
> BUG: KASAN: out-of-bounds in rcu_nmi_enter+0x6e/0xf0
> Read of size 4 at addr ff11000034e38b10 by task swapper/0/0

I haven't seen this without your patches, although it's the exact same
callsite so I assume it must be related to the first problem.


Vegard