mm/hwpoison: Check the subpage, not the head page

[PATCH] mm/hwpoison: Check the subpage, not the head page

Posted by Matthew Wilcox (Oracle) 4 years, 5 months ago

Hardware poison is tracked on a per-page basis, not on the head page.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/rmap.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/rmap.c b/mm/rmap.c
index 6a1e8c7f6213..09b08888120e 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1553,7 +1553,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
 		/* Update high watermark before we lower rss */
 		update_hiwater_rss(mm);
 
-		if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
+		if (PageHWPoison(subpage) && !(flags & TTU_IGNORE_HWPOISON)) {
 			pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
 			if (PageHuge(page)) {
 				hugetlb_count_sub(compound_nr(page), mm);
@@ -1873,7 +1873,7 @@ static bool try_to_migrate_one(struct page *page, struct vm_area_struct *vma,
 			 * memory are supported.
 			 */
 			subpage = page;
-		} else if (PageHWPoison(page)) {
+		} else if (PageHWPoison(subpage)) {
 			pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
 			if (PageHuge(page)) {
 				hugetlb_count_sub(compound_nr(page), mm);
-- 
2.34.1

Re: [PATCH] mm/hwpoison: Check the subpage, not the head page

Posted by Yang Shi 4 years, 4 months ago

On Sat, Jan 29, 2022 at 5:30 PM Matthew Wilcox (Oracle)
<willy@infradead.org> wrote:
>
> Hardware poison is tracked on a per-page basis, not on the head page.

Looks correct to me. Reviewed-by: Yang Shi <shy828301@gmail.com>

>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>  mm/rmap.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 6a1e8c7f6213..09b08888120e 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1553,7 +1553,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
>                 /* Update high watermark before we lower rss */
>                 update_hiwater_rss(mm);
>
> -               if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
> +               if (PageHWPoison(subpage) && !(flags & TTU_IGNORE_HWPOISON)) {
>                         pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
>                         if (PageHuge(page)) {
>                                 hugetlb_count_sub(compound_nr(page), mm);
> @@ -1873,7 +1873,7 @@ static bool try_to_migrate_one(struct page *page, struct vm_area_struct *vma,
>                          * memory are supported.
>                          */
>                         subpage = page;
> -               } else if (PageHWPoison(page)) {
> +               } else if (PageHWPoison(subpage)) {
>                         pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
>                         if (PageHuge(page)) {
>                                 hugetlb_count_sub(compound_nr(page), mm);
> --
> 2.34.1
>
>

Re: [PATCH] mm/hwpoison: Check the subpage, not the head page

Posted by David Rientjes 4 years, 5 months ago

On Sun, 30 Jan 2022, Matthew Wilcox (Oracle) wrote:

> Hardware poison is tracked on a per-page basis, not on the head page.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
>  mm/rmap.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 6a1e8c7f6213..09b08888120e 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1553,7 +1553,7 @@ static bool try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
>  		/* Update high watermark before we lower rss */
>  		update_hiwater_rss(mm);
>  
> -		if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
> +		if (PageHWPoison(subpage) && !(flags & TTU_IGNORE_HWPOISON)) {
>  			pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
>  			if (PageHuge(page)) {
>  				hugetlb_count_sub(compound_nr(page), mm);
> @@ -1873,7 +1873,7 @@ static bool try_to_migrate_one(struct page *page, struct vm_area_struct *vma,
>  			 * memory are supported.
>  			 */
>  			subpage = page;
> -		} else if (PageHWPoison(page)) {
> +		} else if (PageHWPoison(subpage)) {
>  			pteval = swp_entry_to_pte(make_hwpoison_entry(subpage));
>  			if (PageHuge(page)) {
>  				hugetlb_count_sub(compound_nr(page), mm);

This looks correct.  Correct me if I'm wrong that this is for consistency 
and cleanup and that there is no bug being fixed by this, however.

Thanks!