From: Oscar Salvador <osalvador@suse.de>
To: akpm@linux-foundation.org
Cc: n-horiguchi@ah.jp.nec.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org,
Naoya Horiguchi <naoya.horiguchi@nec.com>,
Oscar Salvador <osalvador@suse.de>
Subject: [PATCH 3/7] mm,madvise: call soft_offline_page() without MF_COUNT_INCREASED
Date: Thu, 19 Nov 2020 11:57:12 +0100 [thread overview]
Message-ID: <20201119105716.5962-4-osalvador@suse.de> (raw)
In-Reply-To: <20201119105716.5962-1-osalvador@suse.de>
From: Naoya Horiguchi <naoya.horiguchi@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().
Note that the target page is still pinned after this put_page() because
the current process should have refcount from mapping.
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Signed-off-by: Oscar Salvador <osalvador@suse.de>
---
mm/madvise.c | 19 +++++++++++--------
1 file changed, 11 insertions(+), 8 deletions(-)
diff --git a/mm/madvise.c b/mm/madvise.c
index c6b5524add58..7a0f64b93635 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -900,20 +900,23 @@ static int madvise_inject_error(int behavior,
*/
size = page_size(compound_head(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 (behavior == MADV_SOFT_OFFLINE) {
pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
pfn, start);
- ret = soft_offline_page(pfn, MF_COUNT_INCREASED);
+ ret = soft_offline_page(pfn, 0);
} else {
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);
}
--
2.26.2
next prev parent reply other threads:[~2020-11-19 10:57 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-19 10:57 [PATCH 0/7] HWPoison: Refactor get page interface Oscar Salvador
2020-11-19 10:57 ` [PATCH 1/7] mm,hwpoison: Refactor get_any_page Oscar Salvador
2020-11-20 1:33 ` HORIGUCHI NAOYA(堀口 直也)
2020-11-25 16:54 ` Vlastimil Babka
2020-11-19 10:57 ` [PATCH 2/7] mm,hwpoison: Drop pfn parameter Oscar Salvador
2020-11-20 1:33 ` HORIGUCHI NAOYA(堀口 直也)
2020-11-25 16:55 ` Vlastimil Babka
2020-11-19 10:57 ` Oscar Salvador [this message]
2020-11-25 18:20 ` [PATCH 3/7] mm,madvise: call soft_offline_page() without MF_COUNT_INCREASED Vlastimil Babka
2020-12-01 11:35 ` Oscar Salvador
2020-12-04 17:25 ` Vlastimil Babka
2020-12-05 15:34 ` Oscar Salvador
2020-12-07 2:34 ` HORIGUCHI NAOYA(堀口 直也)
2020-12-07 7:24 ` Oscar Salvador
2020-11-19 10:57 ` [PATCH 4/7] mm,hwpoison: remove MF_COUNT_INCREASED Oscar Salvador
2020-11-19 10:57 ` [PATCH 5/7] mm,hwpoison: remove flag argument from soft offline functions Oscar Salvador
2020-11-19 10:57 ` [PATCH 6/7] mm,hwpoison: Disable pcplists before grabbing a refcount Oscar Salvador
2020-11-20 1:33 ` HORIGUCHI NAOYA(堀口 直也)
2020-11-26 13:45 ` Vlastimil Babka
2020-11-28 0:51 ` Andrew Morton
2020-11-19 10:57 ` [PATCH 7/7] mm,hwpoison: Remove drain_all_pages from shake_page Oscar Salvador
2020-11-20 1:33 ` HORIGUCHI NAOYA(堀口 直也)
2020-11-26 13:52 ` Vlastimil Babka
2020-11-27 7:20 ` Oscar Salvador
2020-12-02 13:34 ` [PATCH 0/7] HWPoison: Refactor get page interface Qian Cai
2020-12-02 13:41 ` Oscar Salvador
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