linux-kernel - Re: [PATCH 5/6] mm, hwpoison: kill procs if unmap fails

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Date:   Fri, 19 Aug 2022 08:18:15 +0000
From:   HORIGUCHI NAOYA(堀口　直也) 
        <naoya.horiguchi@....com>
To:     Miaohe Lin <linmiaohe@...wei.com>
CC:     "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 5/6] mm, hwpoison: kill procs if unmap fails

On Fri, Aug 19, 2022 at 03:37:23PM +0800, Miaohe Lin wrote:
> On 2022/8/19 13:24, HORIGUCHI NAOYA(堀口 直也) wrote:
> > On Thu, Aug 18, 2022 at 09:00:15PM +0800, Miaohe Lin wrote:
> >> If try_to_unmap() fails, the hwpoisoned page still resides in the address
> >> space of some processes. We should kill these processes or the hwpoisoned
> >> page might be consumed later. collect_procs() is always called to collect
> >> relevant processes now so they can be killed later if unmap fails.
> >>
> >> Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
> >> ---
> >>  mm/memory-failure.c | 9 ++++-----
> >>  1 file changed, 4 insertions(+), 5 deletions(-)
> >>
> >> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> >> index a2f4e8b00a26..5f9615a86296 100644
> >> --- a/mm/memory-failure.c
> >> +++ b/mm/memory-failure.c
> >> @@ -1396,7 +1396,7 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
> >>  	struct address_space *mapping;
> >>  	LIST_HEAD(tokill);
> >>  	bool unmap_success;
> >> -	int kill = 1, forcekill;
> >> +	int forcekill;
> >>  	bool mlocked = PageMlocked(hpage);
> >>  
> >>  	/*
> >> @@ -1437,7 +1437,6 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
> >>  		if (page_mkclean(hpage)) {
> >>  			SetPageDirty(hpage);
> >>  		} else {
> >> -			kill = 0;
> >>  			ttu |= TTU_IGNORE_HWPOISON;
> >>  			pr_info("%#lx: corrupted page was clean: dropped without side effects\n",
> >>  				pfn);
> >> @@ -1452,8 +1451,7 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
> >>  	 * Error handling: We ignore errors here because
> >>  	 * there's nothing that can be done.
> > 
> > This above comment might be deprecated now (I'm not sure what this really mean),
> > so could you drop or update this?
> 
> Do you mean remove the below comment? In fact, this doesn't make much sense for me.
> 
> * Error handling: We ignore errors here because
> * there's nothing that can be done.

Yes, that's what I meant.

Thanks,
Naoya Horiguchi