linux-kernel - Re: [PATCH 4/4] x86/mce: Avoid infinite loop for copy from user recovery

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Message-ID: <20210408133631.GJ10192@zn.tnic>
Date:   Thu, 8 Apr 2021 15:36:31 +0200
From:   Borislav Petkov <bp@...en8.de>
To:     Tony Luck <tony.luck@...el.com>
Cc:     x86@...nel.org, linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Andy Lutomirski <luto@...nel.org>,
        Aili Yao <yaoaili@...gsoft.com>,
        HORIGUCHI NAOYA( 堀口　直也) 
        <naoya.horiguchi@....com>
Subject: Re: [PATCH 4/4] x86/mce: Avoid infinite loop for copy from user
 recovery

On Thu, Mar 25, 2021 at 05:02:35PM -0700, Tony Luck wrote:
...
> Expected worst case is two machine checks before moving on (e.g. one user
> access with page faults disabled, then a repeat to the same addrsss with
> page faults enabled). Just in case there is some code that loops forever
> enforce a limit of 10.
> 
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---
>  arch/x86/kernel/cpu/mce/core.c | 40 ++++++++++++++++++++++++++--------
>  include/linux/sched.h          |  1 +
>  2 files changed, 32 insertions(+), 9 deletions(-)

What I'm still unclear on, does this new version address that
"mysterious" hang or panic which the validation team triggered or you
haven't checked yet?

Thx.

-- 
Regards/Gruss,
    Boris.

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