From: Michal Hocko <mhocko@kernel.org>
To: Oscar Salvador <osalvador@suse.de>
Cc: n-horiguchi@ah.jp.nec.com, mike.kravetz@oracle.com,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH v2 02/16] mm,madvise: call soft_offline_page() without MF_COUNT_INCREASED
Date: Fri, 18 Oct 2019 13:52:27 +0200 [thread overview]
Message-ID: <20191018115227.GL5017@dhcp22.suse.cz> (raw)
In-Reply-To: <20191017142123.24245-3-osalvador@suse.de>
On Thu 17-10-19 16:21:09, Oscar Salvador wrote:
> From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
>
> The call to get_user_pages_fast is only to get the pointer to a struct
> page of a given address, pinning it is memory-poisoning handler's job,
> so drop the refcount grabbed by get_user_pages_fast
>
> Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Signed-off-by: Oscar Salvador <osalvador@suse.de>
> ---
> mm/madvise.c | 24 ++++++++++++------------
> 1 file changed, 12 insertions(+), 12 deletions(-)
>
> diff --git a/mm/madvise.c b/mm/madvise.c
> index 2be9f3fdb05e..89ed9a22ff4f 100644
> --- a/mm/madvise.c
> +++ b/mm/madvise.c
> @@ -878,16 +878,24 @@ static int madvise_inject_error(int behavior,
> */
> order = compound_order(compound_head(page));
>
> - if (PageHWPoison(page)) {
> - put_page(page);
> + /*
> + * 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);
> +
> + if (PageHWPoison(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);
What does prevent this struct page to go away completely?
> if (ret)
> return ret;
> continue;
> @@ -895,14 +903,6 @@ static int madvise_inject_error(int behavior,
>
> pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
> pfn, start);
> -
> - /*
> - * Drop the page reference taken by get_user_pages_fast(). In
> - * the absence of MF_COUNT_INCREASED the memory_failure()
> - * routine is responsible for pinning the page to prevent it
> - * from being released back to the page allocator.
> - */
> - put_page(page);
> ret = memory_failure(pfn, 0);
> if (ret)
> return ret;
> --
> 2.12.3
>
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2019-10-18 11:52 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-17 14:21 [RFC PATCH v2 00/16] Hwpoison rework {hard,soft}-offline Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 01/16] mm,hwpoison: cleanup unused PageHuge() check Oscar Salvador
2019-10-18 11:48 ` Michal Hocko
2019-10-21 7:00 ` Naoya Horiguchi
2019-10-21 12:16 ` Michal Hocko
2019-11-12 12:22 ` Aneesh Kumar K.V
2019-11-13 6:02 ` Naoya Horiguchi
2019-10-17 14:21 ` [RFC PATCH v2 02/16] mm,madvise: call soft_offline_page() without MF_COUNT_INCREASED Oscar Salvador
2019-10-18 11:52 ` Michal Hocko [this message]
2019-10-21 7:02 ` Naoya Horiguchi
2019-10-21 12:20 ` Michal Hocko
2019-10-17 14:21 ` [RFC PATCH v2 03/16] mm,madvise: Refactor madvise_inject_error Oscar Salvador
2019-10-21 7:03 ` Naoya Horiguchi
2019-10-17 14:21 ` [RFC PATCH v2 04/16] mm,hwpoison-inject: don't pin for hwpoison_filter Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 05/16] mm,hwpoison: Un-export get_hwpoison_page and make it static Oscar Salvador
2019-10-21 7:03 ` Naoya Horiguchi
2019-10-17 14:21 ` [RFC PATCH v2 06/16] mm,hwpoison: Kill put_hwpoison_page Oscar Salvador
2019-10-21 7:04 ` Naoya Horiguchi
2019-10-17 14:21 ` [RFC PATCH v2 07/16] mm,hwpoison: remove MF_COUNT_INCREASED Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 08/16] mm,hwpoison: remove flag argument from soft offline functions Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 09/16] mm,hwpoison: Unify THP handling for hard and soft offline Oscar Salvador
2019-10-21 7:04 ` Naoya Horiguchi
2019-10-21 9:51 ` [PATCH 17/16] mm,hwpoison: introduce MF_MSG_UNSPLIT_THP Naoya Horiguchi
2019-10-22 8:00 ` Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 10/16] mm,hwpoison: Rework soft offline for free pages Oscar Salvador
2019-10-18 12:06 ` Michal Hocko
2019-10-21 12:58 ` Oscar Salvador
2019-10-21 15:41 ` Michal Hocko
2019-10-22 7:46 ` Oscar Salvador
2019-10-22 8:26 ` Michal Hocko
2019-10-22 8:35 ` Oscar Salvador
2019-10-22 9:22 ` Michal Hocko
2019-10-22 9:58 ` Oscar Salvador
2019-10-22 10:24 ` Michal Hocko
2019-10-22 10:33 ` Oscar Salvador
2019-10-23 2:15 ` Naoya Horiguchi
2019-10-23 2:01 ` Naoya Horiguchi
2019-10-21 7:45 ` Naoya Horiguchi
2019-10-22 8:00 ` Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 11/16] mm,hwpoison: Rework soft offline for in-use pages Oscar Salvador
2019-10-18 12:39 ` Michal Hocko
2019-10-21 13:48 ` Oscar Salvador
2019-10-21 14:06 ` Michal Hocko
2019-10-22 7:56 ` Oscar Salvador
2019-10-22 8:30 ` Michal Hocko
2019-10-22 9:40 ` Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 12/16] mm,hwpoison: Refactor soft_offline_huge_page and __soft_offline_page Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 13/16] mm,hwpoison: Take pages off the buddy when hard-offlining Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 14/16] mm,hwpoison: Return 0 if the page is already poisoned in soft-offline Oscar Salvador
2019-10-21 9:20 ` Naoya Horiguchi
2019-10-17 14:21 ` [RFC PATCH v2 15/16] mm/hwpoison-inject: Rip off duplicated checks Oscar Salvador
2019-10-21 9:40 ` David Hildenbrand
2019-10-22 7:57 ` Oscar Salvador
2019-10-17 14:21 ` [RFC PATCH v2 16/16] mm, soft-offline: convert parameter to pfn Oscar Salvador
2019-10-18 8:15 ` David Hildenbrand
2020-06-11 16:43 ` [RFC PATCH v2 00/16] Hwpoison rework {hard,soft}-offline Dmitry Yakunin
2020-06-15 6:19 ` HORIGUCHI NAOYA(堀口 直也)
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