linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Anshuman Khandual <anshuman.khandual@arm.com>
To: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Michal Hocko <mhocko@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	xishi.qiuxishi@alibaba-inc.com,
	Laurent Dufour <ldufour@linux.vnet.ibm.com>
Subject: Re: [RFC][PATCH v1 04/11] mm: madvise: call soft_offline_page() without MF_COUNT_INCREASED
Date: Fri, 9 Nov 2018 16:16:55 +0530	[thread overview]
Message-ID: <21e5b9ca-ad72-b0d5-3397-4b65831b236b@arm.com> (raw)
In-Reply-To: <1541746035-13408-5-git-send-email-n-horiguchi@ah.jp.nec.com>



On 11/09/2018 12:17 PM, Naoya Horiguchi wrote:
> Currently madvise_inject_error() pins the target page when calling
> memory error handler, but it's not good because the refcount is just
> an artifact of error injector and mock nothing about hw error itself.
> IOW, pinning the error page is part of error handler's task, so
> let's stop doing it.

Did not get that. Could you please kindly explain how an incremented
ref count through get_user_pages_fast() was a mocking the HW error
previously ? Though I might be missing the some context here.

> 
> Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> ---
>  mm/madvise.c | 25 +++++++++++--------------
>  1 file changed, 11 insertions(+), 14 deletions(-)
> 
> diff --git v4.19-mmotm-2018-10-30-16-08/mm/madvise.c v4.19-mmotm-2018-10-30-16-08_patched/mm/madvise.c
> index 6cb1ca9..9fa0225 100644
> --- v4.19-mmotm-2018-10-30-16-08/mm/madvise.c
> +++ v4.19-mmotm-2018-10-30-16-08_patched/mm/madvise.c
> @@ -637,6 +637,16 @@ static int madvise_inject_error(int behavior,
>  		ret = get_user_pages_fast(start, 1, 0, &page);
>  		if (ret != 1)
>  			return ret;
> +		/*
> +		 * The get_user_pages_fast() is just to get the pfn of the
> +		 * given address, and the refcount has nothing to do with
> +		 * what we try to test, so it should be released immediately.
> +		 * This is racy but it's intended because the real hardware
> +		 * errors could happen at any moment and memory error handlers
> +		 * must properly handle the race.
> +		 */
> +		put_page(page);
> +
>  		pfn = page_to_pfn(page);
>  
>  		/*
> @@ -646,16 +656,11 @@ static int madvise_inject_error(int behavior,
>  		 */
>  		order = compound_order(compound_head(page));
>  
> -		if (PageHWPoison(page)) {
> -			put_page(page);
> -			continue;
> -		}
> -
>  		if (behavior == MADV_SOFT_OFFLINE) {
>  			pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
>  					pfn, start);
>  
> -			ret = soft_offline_page(page, MF_COUNT_INCREASED);
> +			ret = soft_offline_page(page, 0);

Probably something defined as a new "ignored" in the memory faults flag
enumeration instead of passing '0' directly.

  reply	other threads:[~2018-11-09 10:47 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-09  6:47 [PATCH RFC v1 00/11] hwpoison improvement part 1 Naoya Horiguchi
2018-11-09  6:47 ` [RFC][PATCH v1 01/11] mm: hwpoison: cleanup unused PageHuge() check Naoya Horiguchi
2018-11-09  9:52   ` Anshuman Khandual
2018-11-09  6:47 ` [RFC][PATCH v1 02/11] mm: soft-offline: add missing error check of set_hwpoison_free_buddy_page() Naoya Horiguchi
2018-11-09 10:20   ` Anshuman Khandual
2018-11-13  0:16     ` Naoya Horiguchi
2018-11-14  8:53       ` Anshuman Khandual
2018-11-09  6:47 ` [RFC][PATCH v1 03/11] mm: move definition of num_poisoned_pages_inc/dec to include/linux/mm.h Naoya Horiguchi
2018-11-09 10:28   ` Anshuman Khandual
2018-11-13  0:17     ` Naoya Horiguchi
2018-11-09  6:47 ` [RFC][PATCH v1 04/11] mm: madvise: call soft_offline_page() without MF_COUNT_INCREASED Naoya Horiguchi
2018-11-09 10:46   ` Anshuman Khandual [this message]
2018-11-13  0:18     ` Naoya Horiguchi
2018-11-09  6:47 ` [RFC][PATCH v1 05/11] mm: hwpoison-inject: don't pin for hwpoison_filter() Naoya Horiguchi
2018-11-09  6:47 ` [RFC][PATCH v1 06/11] mm: hwpoison: remove MF_COUNT_INCREASED Naoya Horiguchi
2018-11-09  6:47 ` [RFC][PATCH v1 07/11] mm: remove flag argument from soft offline functions Naoya Horiguchi
2018-11-09  6:47 ` [RFC][PATCH v1 08/11] mm: soft-offline: isolate error pages from buddy freelist Naoya Horiguchi
2018-11-09  6:47 ` [RFC][PATCH v1 09/11] mm: hwpoison: apply buddy page handling code to hard-offline Naoya Horiguchi
2018-11-09  6:47 ` [RFC][PATCH v1 10/11] mm: clear PageHWPoison in memory hotremove Naoya Horiguchi
2018-11-13  1:32   ` Naoya Horiguchi
2018-11-09  6:47 ` [RFC][PATCH v1 11/11] mm: hwpoison: introduce clear_hwpoison_free_buddy_page() Naoya Horiguchi
2018-11-09 11:33   ` Anshuman Khandual
2018-11-13  0:19     ` Naoya Horiguchi
2018-11-14  8:23       ` Anshuman Khandual

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=21e5b9ca-ad72-b0d5-3397-4b65831b236b@arm.com \
    --to=anshuman.khandual@arm.com \
    --cc=akpm@linux-foundation.org \
    --cc=ldufour@linux.vnet.ibm.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=mhocko@kernel.org \
    --cc=mike.kravetz@oracle.com \
    --cc=n-horiguchi@ah.jp.nec.com \
    --cc=xishi.qiuxishi@alibaba-inc.com \
    --subject='Re: [RFC][PATCH v1 04/11] mm: madvise: call soft_offline_page() without MF_COUNT_INCREASED' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).