diff mbox series

[4/3] mm, hugetlb, hwpoison: separate branch for free and in-use hugepage

Message ID 20220415041848.GA3034499@ik1-406-35019.vs.sakura.ne.jp (mailing list archive)
State New
Headers show
Series mm/hwpoison: fix race between hugetlb free/demotion and memory_failure_hugetlb() | expand

Commit Message

Naoya Horiguchi April 15, 2022, 4:18 a.m. UTC 
From: Naoya Horiguchi <naoya.horiguchi@nec.com>

We know that HPageFreed pages should have page refcount 0, so
get_page_unless_zero() always fails and returns 0.  So explicitly separate
the branch based on page state for minor optimization and better readability.

Suggested-by: Mike Kravetz <mike.kravetz@oracle.com>
Suggested-by: Miaohe Lin <linmiaohe@huawei.com>
Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
---
 mm/hugetlb.c        | 4 +++-
 mm/memory-failure.c | 4 +++-
 2 files changed, 6 insertions(+), 2 deletions(-)

Comments

Mike Kravetz April 15, 2022, 3:11 p.m. UTC | #1 
On 4/14/22 21:18, Naoya Horiguchi wrote:
> From: Naoya Horiguchi <naoya.horiguchi@nec.com>
> 
> We know that HPageFreed pages should have page refcount 0, so
> get_page_unless_zero() always fails and returns 0.  So explicitly separate
> the branch based on page state for minor optimization and better readability.
> 
> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com>
> Suggested-by: Miaohe Lin <linmiaohe@huawei.com>
> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
> ---
>  mm/hugetlb.c        | 4 +++-
>  mm/memory-failure.c | 4 +++-
>  2 files changed, 6 insertions(+), 2 deletions(-)

Thank you!

Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Miaohe Lin April 16, 2022, 1:06 a.m. UTC | #2 
On 2022/4/15 12:18, Naoya Horiguchi wrote:
> From: Naoya Horiguchi <naoya.horiguchi@nec.com>
> 
> We know that HPageFreed pages should have page refcount 0, so
> get_page_unless_zero() always fails and returns 0.  So explicitly separate
> the branch based on page state for minor optimization and better readability.
> 
> Suggested-by: Mike Kravetz <mike.kravetz@oracle.com>
> Suggested-by: Miaohe Lin <linmiaohe@huawei.com>
> Signed-off-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
> ---
>  mm/hugetlb.c        | 4 +++-
>  mm/memory-failure.c | 4 +++-
>  2 files changed, 6 insertions(+), 2 deletions(-)
> 

Thanks!

Reviewed-by: Miaohe Lin <linmiaohe@huawei.com>

> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index e38cbfdf3e61..3638f166e554 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -6786,7 +6786,9 @@ int get_hwpoison_huge_page(struct page *page, bool *hugetlb)
>  	spin_lock_irq(&hugetlb_lock);
>  	if (PageHeadHuge(page)) {
>  		*hugetlb = true;
> -		if (HPageFreed(page) || HPageMigratable(page))
> +		if (HPageFreed(page))
> +			ret = 0;
> +		else if (HPageMigratable(page))
>  			ret = get_page_unless_zero(page);
>  		else
>  			ret = -EBUSY;
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 5e3ad640f5bb..661079a37f29 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1517,7 +1517,9 @@ int __get_huge_page_for_hwpoison(unsigned long pfn, int flags)
>  	if (flags & MF_COUNT_INCREASED) {
>  		ret = 1;
>  		count_increased = true;
> -	} else if (HPageFreed(head) || HPageMigratable(head)) {
> +	} else if (HPageFreed(head)) {
> +		ret = 0;
> +	} else if (HPageMigratable(head)) {
>  		ret = get_page_unless_zero(head);
>  		if (ret)
>  			count_increased = true;
>
diff mbox series

Patch

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index e38cbfdf3e61..3638f166e554 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6786,7 +6786,9 @@  int get_hwpoison_huge_page(struct page *page, bool *hugetlb)
 	spin_lock_irq(&hugetlb_lock);
 	if (PageHeadHuge(page)) {
 		*hugetlb = true;
-		if (HPageFreed(page) || HPageMigratable(page))
+		if (HPageFreed(page))
+			ret = 0;
+		else if (HPageMigratable(page))
 			ret = get_page_unless_zero(page);
 		else
 			ret = -EBUSY;
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 5e3ad640f5bb..661079a37f29 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1517,7 +1517,9 @@  int __get_huge_page_for_hwpoison(unsigned long pfn, int flags)
 	if (flags & MF_COUNT_INCREASED) {
 		ret = 1;
 		count_increased = true;
-	} else if (HPageFreed(head) || HPageMigratable(head)) {
+	} else if (HPageFreed(head)) {
+		ret = 0;
+	} else if (HPageMigratable(head)) {
 		ret = get_page_unless_zero(head);
 		if (ret)
 			count_increased = true;