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

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Message-Id: <788DFBA0-903F-4548-9C2F-B1A1543EE770@amacapital.net>
Date:   Tue, 23 Feb 2021 07:33:46 -0800
From:   Andy Lutomirski <luto@...capital.net>
To:     Aili Yao <yaoaili@...gsoft.com>
Cc:     =?utf-8?Q?
         "HORIGUCHI_NAOYA=28=E5=A0=80=E5=8F=A3=E3=80=80=E7=9B=B4?=
        =?utf-8?Q?=E4=B9=9F=29" ?= <naoya.horiguchi@....com>,
        tony.luck@...el.com, dave.hansen@...ux.intel.com, luto@...nel.org,
        peterz@...radead.org, tglx@...utronix.de, mingo@...hat.com,
        bp@...en8.de, hpa@...or.com, x86@...nel.org,
        yangfeng1@...gsoft.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] x86/fault: Send a SIGBUS to user process always for hwpoison page access.


> On Feb 23, 2021, at 4:44 AM, Aili Yao <yaoaili@...gsoft.com> wrote:
> 
> On Fri, 5 Feb 2021 17:01:35 +0800
> Aili Yao <yaoaili@...gsoft.com> wrote:
> 
>> When one page is already hwpoisoned by MCE AO action, processes may not
>> be killed, processes mapping this page may make a syscall include this
>> page and result to trigger a VM_FAULT_HWPOISON fault, as it's in kernel
>> mode it may be fixed by fixup_exception, current code will just return
>> error code to user code.
>> 
>> This is not sufficient, we should send a SIGBUS to the process and log
>> the info to console, as we can't trust the process will handle the error
>> correctly.
>> 
>> Suggested-by: Feng Yang <yangfeng1@...gsoft.com>
>> Signed-off-by: Aili Yao <yaoaili@...gsoft.com>
>> ---
>> arch/x86/mm/fault.c | 62 +++++++++++++++++++++++++++++----------------
>> 1 file changed, 40 insertions(+), 22 deletions(-)
>> 
> Hi luto;
>  Is there any feedback?

At the very least, this needs a clear explanation of why your proposed behavior is better than the existing behavior.

> 
> Thanks
> Aili Yao