linux-kernel - Re: [PATCH v2 3/3] mm,hwpoison: add kill_accessing

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Date:   Mon, 19 Apr 2021 11:43:53 +0800
From:   Aili Yao <yaoaili@...gsoft.com>
To:     Naoya Horiguchi <nao.horiguchi@...il.com>
CC:     "linux-mm@...ck.org" <linux-mm@...ck.org>,
        Tony Luck <tony.luck@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Oscar Salvador" <osalvador@...e.de>,
        David Hildenbrand <david@...hat.com>,
        Borislav Petkov <bp@...en8.de>,
        Andy Lutomirski <luto@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "HORIGUCHI NAOYA堀口　直也)" 
        <naoya.horiguchi@....com>, <yaoaili@...gsoft.com>
Subject: Re: [PATCH v2 3/3] mm,hwpoison: add kill_accessing_process() to
 find error virtual address

On Mon, 19 Apr 2021 11:36:58 +0900
Naoya Horiguchi <nao.horiguchi@...il.com> wrote:

> > > 2. In the function hwpoison_pte_range():
> > > if (pfn <= hwp->pfn && hwp->pfn < pfn + PMD_SIZE) this check seem we should use PMD_SIZE/PAGE_SIZE or some macro like this?  
> > 
> > Thanks, that's right.  HPAGE_PMD_NR seems to fit here.
> > We also need "#ifdef CONFIG_TRANSPARENT_HUGEPAGE" to use it.  
> 
> I found that the #ifdef is not necessary because the whole
> "if (ptl)" is compiled out.  So I don't add #ifdef.
> 
> Here's the v2 of 3/3.
> 
> Aili, could you test with it?
> 
> Thanks,
> Naoya Horiguchi
> 

I tested this v2 version, In my test, this patches worked as expected and the previous
issues didn't happen again.

Test-by: Aili Yao <yaoaili@...gsoft.com>

Thanks,
Aili Yao

> -----
> From: Naoya Horiguchi <naoya.horiguchi@....com>
> Date: Tue, 13 Apr 2021 07:26:25 +0900
> Subject: [PATCH v2 3/3] mm,hwpoison: add kill_accessing_process() to find error
>  virtual address
> 
> The previous patch solves the infinite MCE loop issue when multiple
> MCE events races.  The remaining issue is to make sure that all threads
> processing Action Required MCEs send to the current processes the
> SIGBUS with the proper virtual address and the error size.
> 
> This patch suggests to do page table walk to find the error virtual
> address.  If we find multiple virtual addresses in walking, we now can't
> determine which one is correct, so we fall back to sending SIGBUS in
> kill_me_maybe() without error info as we do now.  This corner case needs
> to be solved in the future.
> 
> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@....com>
> ---
> change log v1 -> v2:
> - initialize local variables in check_hwpoisoned_entry() and
>   hwpoison_pte_range()
> - fix and improve logic to calculate error address offset.
> ---
>  arch/x86/kernel/cpu/mce/core.c |  13 ++-
>  include/linux/swapops.h        |   5 ++
>  mm/memory-failure.c            | 147 ++++++++++++++++++++++++++++++++-
>  3 files changed, 161 insertions(+), 4 deletions(-)
>