From: Michal Hocko <mhocko@kernel.org>
To: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
Andrew Morton <akpm@linux-foundation.org>,
Zhan Chen <zhanc1@andrew.cmu.edu>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v1] mm: hugetlb: remove incorrect comment
Date: Wed, 20 Jul 2016 11:41:13 +0200 [thread overview]
Message-ID: <20160720094113.GG11249@dhcp22.suse.cz> (raw)
In-Reply-To: <20160720092901.GA15995@www9186uo.sakura.ne.jp>
On Wed 20-07-16 18:29:02, Naoya Horiguchi wrote:
[...]
> >From 7da52ca6920dcd84e3da2df619bd5242f9c3ccec Mon Sep 17 00:00:00 2001
> From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Date: Wed, 20 Jul 2016 18:21:33 +0900
> Subject: [PATCH v2] mm: hwpoison: remove incorrect comment
>
> dequeue_hwpoisoned_huge_page() can be called without page lock hold,
> so let's remove incorrect comment.
>
> The reason why the page lock is not really needed is that
> dequeue_hwpoisoned_huge_page() checks page_huge_active() inside hugetlb_lock,
> which allows us to avoid trying to dequeue a hugepage that are just allocated
> but not linked to active list yet, even without taking page lock.
Thank you for the clarification!
> Reported-by: Zhan Chen <zhanc1@andrew.cmu.edu>
> Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Acked-by: Michal Hocko <mhocko@suse.com>
> ---
> mm/hugetlb.c | 1 -
> mm/memory-failure.c | 2 --
> 2 files changed, 3 deletions(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index c1f3c0be150a..26f735cc7478 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -4401,7 +4401,6 @@ follow_huge_pud(struct mm_struct *mm, unsigned long address,
>
> /*
> * This function is called from memory failure code.
> - * Assume the caller holds page lock of the head page.
> */
> int dequeue_hwpoisoned_huge_page(struct page *hpage)
> {
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 2fcca6b0e005..7532c3a8a39c 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -741,8 +741,6 @@ static int me_huge_page(struct page *p, unsigned long pfn)
> * page->lru because it can be used in other hugepage operations,
> * such as __unmap_hugepage_range() and gather_surplus_pages().
> * So instead we use page_mapping() and PageAnon().
> - * We assume that this function is called with page lock held,
> - * so there is no race between isolation and mapping/unmapping.
> */
> if (!(page_mapping(hpage) || PageAnon(hpage))) {
> res = dequeue_hwpoisoned_huge_page(hpage);
> --
> 2.7.4
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
--
Michal Hocko
SUSE Labs
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
prev parent reply other threads:[~2016-07-20 9:41 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-19 2:08 [PATCH v1] mm: hugetlb: remove incorrect comment Naoya Horiguchi
2016-07-19 9:10 ` Michal Hocko
2016-07-20 9:29 ` Naoya Horiguchi
2016-07-20 9:41 ` Michal Hocko [this message]
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=20160720094113.GG11249@dhcp22.suse.cz \
--to=mhocko@kernel.org \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=n-horiguchi@ah.jp.nec.com \
--cc=nao.horiguchi@gmail.com \
--cc=zhanc1@andrew.cmu.edu \
/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).