From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Michal Hocko <mhocko@kernel.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
"xishi.qiuxishi@alibaba-inc.com" <xishi.qiuxishi@alibaba-inc.com>,
"Laurent Dufour" <ldufour@linux.vnet.ibm.com>
Subject: Re: [RFC][PATCH v1 02/11] mm: soft-offline: add missing error check of set_hwpoison_free_buddy_page()
Date: Tue, 13 Nov 2018 00:16:53 +0000 [thread overview]
Message-ID: <20181113001652.GA5945@hori1.linux.bs1.fc.nec.co.jp> (raw)
In-Reply-To: <9ea93154-4843-231d-d72b-bf12c8807c24@arm.com>
Hi Anshuman,
On Fri, Nov 09, 2018 at 03:50:41PM +0530, Anshuman Khandual wrote:
>
>
> On 11/09/2018 12:17 PM, Naoya Horiguchi wrote:
> > set_hwpoison_free_buddy_page() could fail, then the target page is
> > finally not isolated, so it's better to report -EBUSY for userspace
> > to know the failure and chance of retry.
> >
>
> IIUC set_hwpoison_free_buddy_page() could only fail if the page is not
> free in the buddy. At least for soft_offline_huge_page() that wont be
> the case otherwise dissolve_free_huge_page() would have returned non
> zero -EBUSY. Is there any other reason set_hwpoison_free_buddy_page()
> would not succeed ?
There is a race window between page freeing (after successful soft-offline
-> page migration case) and the containment by set_hwpoison_free_buddy_page().
Or a target page can be allocated just after get_any_page() decided that
the target page is a free page.
So set_hwpoison_free_buddy_page() would safely fail in such cases.
Thanks,
Naoya Horiguchi
>
> > And for consistency, this patch moves set_hwpoison_free_buddy_page()
> > in unmap_and_move() to __soft_offline_page().
>
> Yeah this check should be handled in soft offline functions not inside
> migrations they trigger.
>
next prev parent reply other threads:[~2018-11-13 0:21 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 [this message]
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
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
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