diff mbox series

[v9,06/11] mm/hugetlb: Set the PageHWPoison to the raw error page

Message ID 20201213154534.54826-7-songmuchun@bytedance.com (mailing list archive)
State New, archived
Headers show
Series Free some vmemmap pages of HugeTLB page | expand

Commit Message

Muchun Song Dec. 13, 2020, 3:45 p.m. UTC 
Because we reuse the first tail vmemmap page frame and remap it
with read-only, we cannot set the PageHWPosion on a tail page.
So we can use the head[4].private to record the real error page
index and set the raw error page PageHWPoison later.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
---
 mm/hugetlb.c | 48 ++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 40 insertions(+), 8 deletions(-)

Comments

Oscar Salvador Dec. 16, 2020, 1:28 p.m. UTC | #1 
On Sun, Dec 13, 2020 at 11:45:29PM +0800, Muchun Song wrote:
> Because we reuse the first tail vmemmap page frame and remap it
> with read-only, we cannot set the PageHWPosion on a tail page.
> So we can use the head[4].private to record the real error page
> index and set the raw error page PageHWPoison later.

Maybe the following is better?

"Since the first page of tail page structs is remapped read-only,
 we cannot modify any tail struct page, and so we cannot set
 the HWPoison flag on a tail page.
 We can make use of head[4].private to record the real hwpoisoned
 page index.
 Right before freeing the page the real raw page will be retrieved
 and marked as HWPoison.
"

I think it is slighly clearer, but whatever.

> Signed-off-by: Muchun Song <songmuchun@bytedance.com>

I do not quite like the name hwpoison_subpage_deliver, but I cannot
come up with a better one myself, so:

Reviewed-by: Oscar Salvador <osalvador@suse.de>
Oscar Salvador Dec. 16, 2020, 1:30 p.m. UTC | #2 
On Sun, Dec 13, 2020 at 11:45:29PM +0800, Muchun Song wrote:
> Because we reuse the first tail vmemmap page frame and remap it
> with read-only, we cannot set the PageHWPosion on a tail page.
> So we can use the head[4].private to record the real error page
> index and set the raw error page PageHWPoison later.
> 
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>

+CC Naoya

> ---
>  mm/hugetlb.c | 48 ++++++++++++++++++++++++++++++++++++++++--------
>  1 file changed, 40 insertions(+), 8 deletions(-)
> 
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 542e6cb81321..29de425f879a 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1347,6 +1347,43 @@ static inline void __update_and_free_page(struct hstate *h, struct page *page)
>  		schedule_work(&hpage_update_work);
>  }
>  
> +static inline void hwpoison_subpage_deliver(struct hstate *h, struct page *head)
> +{
> +	struct page *page;
> +
> +	if (!PageHWPoison(head) || !free_vmemmap_pages_per_hpage(h))
> +		return;
> +
> +	page = head + page_private(head + 4);
> +
> +	/*
> +	 * Move PageHWPoison flag from head page to the raw error page,
> +	 * which makes any subpages rather than the error page reusable.
> +	 */
> +	if (page != head) {
> +		SetPageHWPoison(page);
> +		ClearPageHWPoison(head);
> +	}
> +}
> +
> +static inline void hwpoison_subpage_set(struct hstate *h, struct page *head,
> +					struct page *page)
> +{
> +	if (!PageHWPoison(head))
> +		return;
> +
> +	if (free_vmemmap_pages_per_hpage(h)) {
> +		set_page_private(head + 4, page - head);
> +	} else if (page != head) {
> +		/*
> +		 * Move PageHWPoison flag from head page to the raw error page,
> +		 * which makes any subpages rather than the error page reusable.
> +		 */
> +		SetPageHWPoison(page);
> +		ClearPageHWPoison(head);
> +	}
> +}
> +
>  static void update_and_free_page(struct hstate *h, struct page *page)
>  {
>  	if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
> @@ -1363,6 +1400,7 @@ static void __free_hugepage(struct hstate *h, struct page *page)
>  	int i;
>  
>  	alloc_huge_page_vmemmap(h, page);
> +	hwpoison_subpage_deliver(h, page);
>  
>  	for (i = 0; i < pages_per_huge_page(h); i++) {
>  		page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
> @@ -1840,14 +1878,8 @@ int dissolve_free_huge_page(struct page *page)
>  		int nid = page_to_nid(head);
>  		if (h->free_huge_pages - h->resv_huge_pages == 0)
>  			goto out;
> -		/*
> -		 * Move PageHWPoison flag from head page to the raw error page,
> -		 * which makes any subpages rather than the error page reusable.
> -		 */
> -		if (PageHWPoison(head) && page != head) {
> -			SetPageHWPoison(page);
> -			ClearPageHWPoison(head);
> -		}
> +
> +		hwpoison_subpage_set(h, head, page);
>  		list_del(&head->lru);
>  		h->free_huge_pages--;
>  		h->free_huge_pages_node[nid]--;
> -- 
> 2.11.0
>
Muchun Song Dec. 16, 2020, 1:51 p.m. UTC | #3 
On Wed, Dec 16, 2020 at 9:28 PM Oscar Salvador <osalvador@suse.de> wrote:
>
> On Sun, Dec 13, 2020 at 11:45:29PM +0800, Muchun Song wrote:
> > Because we reuse the first tail vmemmap page frame and remap it
> > with read-only, we cannot set the PageHWPosion on a tail page.
> > So we can use the head[4].private to record the real error page
> > index and set the raw error page PageHWPoison later.
>
> Maybe the following is better?
>
> "Since the first page of tail page structs is remapped read-only,
>  we cannot modify any tail struct page, and so we cannot set
>  the HWPoison flag on a tail page.
>  We can make use of head[4].private to record the real hwpoisoned
>  page index.
>  Right before freeing the page the real raw page will be retrieved
>  and marked as HWPoison.
> "
>
> I think it is slighly clearer, but whatever.

Thank you.

>
> > Signed-off-by: Muchun Song <songmuchun@bytedance.com>
>
> I do not quite like the name hwpoison_subpage_deliver, but I cannot
> come up with a better one myself, so:
>
> Reviewed-by: Oscar Salvador <osalvador@suse.de>

Thanks for your review.

>
> --
> Oscar Salvador
> SUSE L3
diff mbox series

Patch

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 542e6cb81321..29de425f879a 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -1347,6 +1347,43 @@  static inline void __update_and_free_page(struct hstate *h, struct page *page)
 		schedule_work(&hpage_update_work);
 }
 
+static inline void hwpoison_subpage_deliver(struct hstate *h, struct page *head)
+{
+	struct page *page;
+
+	if (!PageHWPoison(head) || !free_vmemmap_pages_per_hpage(h))
+		return;
+
+	page = head + page_private(head + 4);
+
+	/*
+	 * Move PageHWPoison flag from head page to the raw error page,
+	 * which makes any subpages rather than the error page reusable.
+	 */
+	if (page != head) {
+		SetPageHWPoison(page);
+		ClearPageHWPoison(head);
+	}
+}
+
+static inline void hwpoison_subpage_set(struct hstate *h, struct page *head,
+					struct page *page)
+{
+	if (!PageHWPoison(head))
+		return;
+
+	if (free_vmemmap_pages_per_hpage(h)) {
+		set_page_private(head + 4, page - head);
+	} else if (page != head) {
+		/*
+		 * Move PageHWPoison flag from head page to the raw error page,
+		 * which makes any subpages rather than the error page reusable.
+		 */
+		SetPageHWPoison(page);
+		ClearPageHWPoison(head);
+	}
+}
+
 static void update_and_free_page(struct hstate *h, struct page *page)
 {
 	if (hstate_is_gigantic(h) && !gigantic_page_runtime_supported())
@@ -1363,6 +1400,7 @@  static void __free_hugepage(struct hstate *h, struct page *page)
 	int i;
 
 	alloc_huge_page_vmemmap(h, page);
+	hwpoison_subpage_deliver(h, page);
 
 	for (i = 0; i < pages_per_huge_page(h); i++) {
 		page[i].flags &= ~(1 << PG_locked | 1 << PG_error |
@@ -1840,14 +1878,8 @@  int dissolve_free_huge_page(struct page *page)
 		int nid = page_to_nid(head);
 		if (h->free_huge_pages - h->resv_huge_pages == 0)
 			goto out;
-		/*
-		 * Move PageHWPoison flag from head page to the raw error page,
-		 * which makes any subpages rather than the error page reusable.
-		 */
-		if (PageHWPoison(head) && page != head) {
-			SetPageHWPoison(page);
-			ClearPageHWPoison(head);
-		}
+
+		hwpoison_subpage_set(h, head, page);
 		list_del(&head->lru);
 		h->free_huge_pages--;
 		h->free_huge_pages_node[nid]--;