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Message-Id: <20190626061124.16013-3-alastair@au1.ibm.com>
Date: Wed, 26 Jun 2019 16:11:22 +1000
From: "Alastair D'Silva" <alastair@....ibm.com>
To: alastair@...ilva.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Pavel Tatashin <pasha.tatashin@...cle.com>,
Oscar Salvador <osalvador@...e.de>,
Michal Hocko <mhocko@...e.com>,
Mike Rapoport <rppt@...ux.ibm.com>,
Baoquan He <bhe@...hat.com>, Qian Cai <cai@....pw>,
Logan Gunthorpe <logang@...tatee.com>,
linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: [PATCH v2 2/3] mm: don't hide potentially null memmap pointer in sparse_remove_one_section
From: Alastair D'Silva <alastair@...ilva.org>
By adding offset to memmap before passing it in to clear_hwpoisoned_pages,
we hide a potentially null memmap from the null check inside
clear_hwpoisoned_pages.
This patch passes the offset to clear_hwpoisoned_pages instead, allowing
memmap to successfully peform it's null check.
Signed-off-by: Alastair D'Silva <alastair@...ilva.org>
---
mm/sparse.c | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
diff --git a/mm/sparse.c b/mm/sparse.c
index 57a1a3d9c1cf..1ec32aef5590 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -753,7 +753,8 @@ int __meminit sparse_add_one_section(int nid, unsigned long start_pfn,
#ifdef CONFIG_MEMORY_HOTREMOVE
#ifdef CONFIG_MEMORY_FAILURE
-static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
+static void clear_hwpoisoned_pages(struct page *memmap,
+ unsigned long start, unsigned long count)
{
int i;
@@ -769,7 +770,7 @@ static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
if (atomic_long_read(&num_poisoned_pages) == 0)
return;
- for (i = 0; i < nr_pages; i++) {
+ for (i = start; i < start + count; i++) {
if (PageHWPoison(&memmap[i])) {
atomic_long_sub(1, &num_poisoned_pages);
ClearPageHWPoison(&memmap[i]);
@@ -777,7 +778,8 @@ static void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
}
}
#else
-static inline void clear_hwpoisoned_pages(struct page *memmap, int nr_pages)
+static inline void clear_hwpoisoned_pages(struct page *memmap,
+ unsigned long start, unsigned long count)
{
}
#endif
@@ -824,7 +826,7 @@ void sparse_remove_one_section(struct zone *zone, struct mem_section *ms,
ms->pageblock_flags = NULL;
}
- clear_hwpoisoned_pages(memmap + map_offset,
+ clear_hwpoisoned_pages(memmap, map_offset,
PAGES_PER_SECTION - map_offset);
free_section_usemap(memmap, usemap, altmap);
}
--
2.21.0
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