linux-kernel - Re: [PATCH v3] x86/fault: Send a SIGBUS to user process always for hwpoison page access.

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Message-ID: <20210309102502.27af8da9@alex-virtual-machine>
Date:   Tue, 9 Mar 2021 10:25:02 +0800
From:   Aili Yao <yaoaili@...gsoft.com>
To:     "Luck, Tony" <tony.luck@...el.com>
CC:     Andy Lutomirski <luto@...capital.net>,
        Andy Lutomirski <luto@...nel.org>,
        HORIGUCHI NAOYA <naoya.horiguchi@....com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, X86 ML <x86@...nel.org>,
        "yangfeng1@...gsoft.com" <yangfeng1@...gsoft.com>,
        Linux-MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>, <yaoaili@...gsoft.com>
Subject: Re: [PATCH v3] x86/fault: Send a SIGBUS to user process always for
 hwpoison page access.

On Tue, 9 Mar 2021 10:14:52 +0800
Aili Yao <yaoaili@...gsoft.com> wrote:

> On Mon, 8 Mar 2021 18:31:07 +0000
> "Luck, Tony" <tony.luck@...el.com> wrote:
> 
> > > Can you point me at that SIGBUS code in a current kernel?    
> > 
> > It is in kill_me_maybe().  mce_vaddr is setup when we disassemble whatever get_user()
> > or copy from user variant was in use in the kernel when the poison memory was consumed.
> > 
> >         if (p->mce_vaddr != (void __user *)-1l) {
> >                 force_sig_mceerr(BUS_MCEERR_AR, p->mce_vaddr, PAGE_SHIFT);
> > 
> > Would it be any better if we used the BUS_MCEERR_AO code that goes into siginfo?
> > 
> > That would make it match up better with what happens when poison is found
> > asynchronously by the patrol scrubber. I.e. the semantics are:
> > 
> > AR: You just touched poison at this address and need to do something about that.
> > AO: Just letting you know that you have some poison at the address in siginfo.
> > 
> > -Tony  
> 
> Is the kill action for this scenario in memory_failure()?

Does the current logic kill the process twice for this scenario ?
I am confused.

-- 
Thanks!
Aili Yao