From: Alastair D'Silva <[email protected]>
By adding offset to memmap before passing it in to clear_hwpoisoned_pages,
is hides 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 <[email protected]>
---
mm/sparse.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/mm/sparse.c b/mm/sparse.c
index 104a79fedd00..66a99da9b11b 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -746,12 +746,14 @@ int __meminit sparse_add_one_section(int nid, unsigned long start_pfn,
kfree(usemap);
__kfree_section_memmap(memmap, altmap);
}
+
return ret;
}
#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 map_offset, int nr_pages)
{
int i;
@@ -767,7 +769,7 @@ 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 = map_offset; i < nr_pages; i++) {
if (PageHWPoison(&memmap[i])) {
atomic_long_sub(1, &num_poisoned_pages);
ClearPageHWPoison(&memmap[i]);
@@ -775,7 +777,8 @@ 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 map_offset, int nr_pages)
{
}
#endif
@@ -822,8 +825,7 @@ void sparse_remove_one_section(struct zone *zone, struct mem_section *ms,
ms->pageblock_flags = NULL;
}
- clear_hwpoisoned_pages(memmap + map_offset,
- PAGES_PER_SECTION - map_offset);
+ clear_hwpoisoned_pages(memmap, map_offset, PAGES_PER_SECTION);
free_section_usemap(memmap, usemap, altmap);
}
#endif /* CONFIG_MEMORY_HOTREMOVE */
--
2.21.0
On Mon, Jun 17, 2019 at 02:36:28PM +1000, Alastair D'Silva wrote:
> From: Alastair D'Silva <[email protected]>
>
> By adding offset to memmap before passing it in to clear_hwpoisoned_pages,
> is hides 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 <[email protected]>
One nit below, otherwise
Reviewed-by: Mike Rapoport <[email protected]>
> ---
> mm/sparse.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/mm/sparse.c b/mm/sparse.c
> index 104a79fedd00..66a99da9b11b 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -746,12 +746,14 @@ int __meminit sparse_add_one_section(int nid, unsigned long start_pfn,
> kfree(usemap);
> __kfree_section_memmap(memmap, altmap);
> }
> +
The whitespace change here is not related
> return ret;
> }
>
> #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 map_offset, int nr_pages)
> {
> int i;
>
> @@ -767,7 +769,7 @@ 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 = map_offset; i < nr_pages; i++) {
> if (PageHWPoison(&memmap[i])) {
> atomic_long_sub(1, &num_poisoned_pages);
> ClearPageHWPoison(&memmap[i]);
> @@ -775,7 +777,8 @@ 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 map_offset, int nr_pages)
> {
> }
> #endif
> @@ -822,8 +825,7 @@ void sparse_remove_one_section(struct zone *zone, struct mem_section *ms,
> ms->pageblock_flags = NULL;
> }
>
> - clear_hwpoisoned_pages(memmap + map_offset,
> - PAGES_PER_SECTION - map_offset);
> + clear_hwpoisoned_pages(memmap, map_offset, PAGES_PER_SECTION);
> free_section_usemap(memmap, usemap, altmap);
> }
> #endif /* CONFIG_MEMORY_HOTREMOVE */
> --
> 2.21.0
>
--
Sincerely yours,
Mike.
On 17.06.19 06:36, Alastair D'Silva wrote:
> From: Alastair D'Silva <[email protected]>
>
> By adding offset to memmap before passing it in to clear_hwpoisoned_pages,
> is hides 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 <[email protected]>
> ---
> mm/sparse.c | 12 +++++++-----
> 1 file changed, 7 insertions(+), 5 deletions(-)
>
> diff --git a/mm/sparse.c b/mm/sparse.c
> index 104a79fedd00..66a99da9b11b 100644
> --- a/mm/sparse.c
> +++ b/mm/sparse.c
> @@ -746,12 +746,14 @@ int __meminit sparse_add_one_section(int nid, unsigned long start_pfn,
> kfree(usemap);
> __kfree_section_memmap(memmap, altmap);
> }
> +
> return ret;
> }
>
> #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 map_offset, int nr_pages)
> {
> int i;
>
> @@ -767,7 +769,7 @@ 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 = map_offset; i < nr_pages; i++) {
> if (PageHWPoison(&memmap[i])) {
> atomic_long_sub(1, &num_poisoned_pages);
> ClearPageHWPoison(&memmap[i]);
> @@ -775,7 +777,8 @@ 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 map_offset, int nr_pages)
I somewhat dislike that map_offset modifies nr_pages internally.
I would prefer decoupling both and passing the actual number of pages to
clear instead:
clear_hwpoisoned_pages(memmap, map_offset,
PAGES_PER_SECTION - map_offset);
> {
> }
> #endif
> @@ -822,8 +825,7 @@ void sparse_remove_one_section(struct zone *zone, struct mem_section *ms,
> ms->pageblock_flags = NULL;
> }
>
> - clear_hwpoisoned_pages(memmap + map_offset,
> - PAGES_PER_SECTION - map_offset);
> + clear_hwpoisoned_pages(memmap, map_offset, PAGES_PER_SECTION);
> free_section_usemap(memmap, usemap, altmap);
> }
> #endif /* CONFIG_MEMORY_HOTREMOVE */
>
--
Thanks,
David / dhildenb