From: Naoya Horiguchi <naoya.horiguchi@linux.dev>
To: zhenwei pi <pizhenwei@bytedance.com>
Cc: akpm@linux-foundation.org, naoya.horiguchi@nec.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Wu Fengguang <fengguang.wu@intel.com>
Subject: Re: [PATCH 3/4] mm/memofy-failure.c: optimize hwpoison_filter
Date: Fri, 6 May 2022 17:59:20 +0900 [thread overview]
Message-ID: <20220506085920.GC1356094@u2004> (raw)
In-Reply-To: <20220429142206.294714-4-pizhenwei@bytedance.com>
On Fri, Apr 29, 2022 at 10:22:05PM +0800, zhenwei pi wrote:
> In the memory failure procedure, hwpoison_filter has higher priority,
> if memory_filter() filters the error event, there is no need to do
> the further work.
Could you clarify what problem you are trying to solve (what does
"optimize" mean in this context or what is the benefit)?
Now hwpoison_filter() can be called both with *and* without taking page refcount.
It's mainly called *with* taking page refcount in order to make sure that the
actual handling process is executed only for pages that meet a given condition.
IOW, it's important to prevent pages which do not meet the condition from going
ahead to further steps (false-positive is not permitted). So this type of
callsite should not be omittable.
As for the other case, hwpoison_filter() is also called in hwpoison_inject()
*without* taking page refcount. This actually has a different nuance and
intended to speculatively filter the injection events before setting
PageHWPoison flag to reduce the noise due to setting PG_hwpoison temporary.
The point is that it's not intended here to filter precisely and this callsite
is omittable.
So in my understanding, we need keep hwpoison_filter() after taking page
refcount as we do now. Maybe optionally and additionally calling
hwpoison_filter() at the beginning of memory_failure() might be possible,
but I'm not sure yet how helpful...
Thanks,
Naoya Horiguchi
>
> Cc: Wu Fengguang <fengguang.wu@intel.com>
> Signed-off-by: zhenwei pi <pizhenwei@bytedance.com>
> ---
> mm/memory-failure.c | 14 +++++---------
> 1 file changed, 5 insertions(+), 9 deletions(-)
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index ece05858568f..a6a27c8b800f 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1800,6 +1800,11 @@ int memory_failure(unsigned long pfn, int flags)
> goto unlock_mutex;
> }
>
> + if (hwpoison_filter(p)) {
> + res = -EOPNOTSUPP;
> + goto unlock_mutex;
> + }
> +
> try_again:
> res = try_memory_failure_hugetlb(pfn, flags, &hugetlb);
> if (hugetlb)
> @@ -1937,15 +1942,6 @@ int memory_failure(unsigned long pfn, int flags)
> */
> page_flags = p->flags;
>
> - if (hwpoison_filter(p)) {
> - if (TestClearPageHWPoison(p))
> - num_poisoned_pages_dec();
> - unlock_page(p);
> - put_page(p);
> - res = -EOPNOTSUPP;
> - goto unlock_mutex;
> - }
> -
> /*
> * __munlock_pagevec may clear a writeback page's LRU flag without
> * page_lock. We need wait writeback completion for this page or it
> --
> 2.20.1
>
next prev parent reply other threads:[~2022-05-06 8:59 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-04-29 14:22 [PATCH 0/4] memory-failure: fix hwpoison_filter zhenwei pi
2022-04-29 14:22 ` [PATCH 1/4] mm/memory-failure.c: move clear_hwpoisoned_pages zhenwei pi
2022-05-06 8:55 ` Naoya Horiguchi
2022-04-29 14:22 ` [PATCH 2/4] mm/memofy-failure.c:: simplify num_poisoned_pages_dec zhenwei pi
2022-05-06 8:55 ` Naoya Horiguchi
2022-04-29 14:22 ` [PATCH 3/4] mm/memofy-failure.c: optimize hwpoison_filter zhenwei pi
2022-05-06 8:59 ` Naoya Horiguchi [this message]
2022-05-06 13:38 ` zhenwei pi
2022-05-06 16:28 ` David Hildenbrand
2022-05-07 0:28 ` zhenwei pi
2022-05-07 8:20 ` Naoya Horiguchi
2022-05-07 9:19 ` zhenwei pi
2022-04-29 14:22 ` [PATCH 4/4] mm/memofy-failure.c: add hwpoison_filter for soft offline zhenwei pi
2022-05-06 8:59 ` Naoya Horiguchi
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=20220506085920.GC1356094@u2004 \
--to=naoya.horiguchi@linux.dev \
--cc=akpm@linux-foundation.org \
--cc=fengguang.wu@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=naoya.horiguchi@nec.com \
--cc=pizhenwei@bytedance.com \
/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
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
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).