On Thu, 16 Jul 2015 01:41:56 +0000 Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> wrote:
> The race condition addressed in commit add05cecef80 ("mm: soft-offline: don't
> free target page in successful page migration") was not closed completely,
> because that can happen not only for soft-offline, but also for hard-offline.
> Consider that a slab page is about to be freed into buddy pool, and then an
> uncorrected memory error hits the page just after entering __free_one_page(),
> then VM_BUG_ON_PAGE(page->flags & PAGE_FLAGS_CHECK_AT_PREP) is triggered,
> despite the fact that it's not necessary because the data on the affected
> page is not consumed.
>
> To solve it, this patch drops __PG_HWPOISON from page flag checks at
> allocation/free time. I think it's justified because __PG_HWPOISON flags is
> defined to prevent the page from being reused and setting it outside the
> page's alloc-free cycle is a designed behavior (not a bug.)
>
> And the patch reverts most of the changes from commit add05cecef80 about
> the new refcounting rule of soft-offlined pages, which is no longer necessary.
>
> ...
>
> --- v4.2-rc2.orig/mm/memory-failure.c
> +++ v4.2-rc2/mm/memory-failure.c
> @@ -1723,6 +1723,9 @@ int soft_offline_page(struct page *page, int flags)
>
> get_online_mems();
>
> + if (get_pageblock_migratetype(page) != MIGRATE_ISOLATE)
> + set_migratetype_isolate(page, true);
> +
> ret = get_any_page(page, pfn, flags);
> put_online_mems();
> if (ret > 0) { /* for in-use pages */
This patch gets build-broken by your
mm-page_isolation-make-set-unset_migratetype_isolate-file-local.patch,
which I shall drop.
From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Subject: mm, page_isolation: make set/unset_migratetype_isolate() file-local
Nowaday, set/unset_migratetype_isolate() is defined and used only in
mm/page_isolation, so let's limit the scope within the file.
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/page-isolation.h | 5 -----
mm/page_isolation.c | 5 +++--
2 files changed, 3 insertions(+), 7 deletions(-)
diff -puN include/linux/page-isolation.h~mm-page_isolation-make-set-unset_migratetype_isolate-file-local include/linux/page-isolation.h
--- a/include/linux/page-isolation.h~mm-page_isolation-make-set-unset_migratetype_isolate-file-local
+++ a/include/linux/page-isolation.h
@@ -65,11 +65,6 @@ undo_isolate_page_range(unsigned long st
int test_pages_isolated(unsigned long start_pfn, unsigned long end_pfn,
bool skip_hwpoisoned_pages);
-/*
- * Internal functions. Changes pageblock's migrate type.
- */
-int set_migratetype_isolate(struct page *page, bool skip_hwpoisoned_pages);
-void unset_migratetype_isolate(struct page *page, unsigned migratetype);
struct page *alloc_migrate_target(struct page *page, unsigned long private,
int **resultp);
diff -puN mm/page_isolation.c~mm-page_isolation-make-set-unset_migratetype_isolate-file-local mm/page_isolation.c
--- a/mm/page_isolation.c~mm-page_isolation-make-set-unset_migratetype_isolate-file-local
+++ a/mm/page_isolation.c
@@ -9,7 +9,8 @@
#include <linux/hugetlb.h>
#include "internal.h"
-int set_migratetype_isolate(struct page *page, bool skip_hwpoisoned_pages)
+static int set_migratetype_isolate(struct page *page,
+ bool skip_hwpoisoned_pages)
{
struct zone *zone;
unsigned long flags, pfn;
@@ -72,7 +73,7 @@ out:
return ret;
}
-void unset_migratetype_isolate(struct page *page, unsigned migratetype)
+static void unset_migratetype_isolate(struct page *page, unsigned migratetype)
{
struct zone *zone;
unsigned long flags, nr_pages;
_
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