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Date: Wed, 1 Apr 2015 18:36:24 +0200
From: Michal Hocko <mhocko@...e.cz>
To: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Hugh Dickins <hughd@...gle.com>, Mel Gorman <mgorman@...e.de>,
Johannes Weiner <hannes@...xchg.org>,
David Rientjes <rientjes@...gle.com>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
Naoya Horiguchi <nao.horiguchi@...il.com>
Subject: Re: [PATCH v3 3/3] mm: hugetlb: cleanup using PageHugeActive flag
On Tue 31-03-15 08:50:46, Naoya Horiguchi wrote:
> Now we have an easy access to hugepages' activeness, so existing helpers to
> get the information can be cleaned up.
>
> Signed-off-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Reviewed-by: Michal Hocko <mhocko@...e.cz>
> ---
> include/linux/hugetlb.h | 8 ++++++--
> mm/hugetlb.c | 42 +++++-------------------------------------
> mm/memory_hotplug.c | 2 +-
> 3 files changed, 12 insertions(+), 40 deletions(-)
>
> diff --git v4.0-rc6.orig/include/linux/hugetlb.h v4.0-rc6/include/linux/hugetlb.h
> index 7b5785032049..8494abed02a5 100644
> --- v4.0-rc6.orig/include/linux/hugetlb.h
> +++ v4.0-rc6/include/linux/hugetlb.h
> @@ -42,6 +42,7 @@ struct hugepage_subpool *hugepage_new_subpool(long nr_blocks);
> void hugepage_put_subpool(struct hugepage_subpool *spool);
>
> int PageHuge(struct page *page);
> +int PageHugeActive(struct page *page);
>
> void reset_vma_resv_huge_pages(struct vm_area_struct *vma);
> int hugetlb_sysctl_handler(struct ctl_table *, int, void __user *, size_t *, loff_t *);
> @@ -79,7 +80,6 @@ void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed);
> int dequeue_hwpoisoned_huge_page(struct page *page);
> bool isolate_huge_page(struct page *page, struct list_head *list);
> void putback_active_hugepage(struct page *page);
> -bool is_hugepage_active(struct page *page);
> void free_huge_page(struct page *page);
>
> #ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
> @@ -114,6 +114,11 @@ static inline int PageHuge(struct page *page)
> return 0;
> }
>
> +static inline int PageHugeActive(struct page *page)
> +{
> + return 0;
> +}
> +
> static inline void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
> {
> }
> @@ -152,7 +157,6 @@ static inline bool isolate_huge_page(struct page *page, struct list_head *list)
> return false;
> }
> #define putback_active_hugepage(p) do {} while (0)
> -#define is_hugepage_active(x) false
>
> static inline unsigned long hugetlb_change_protection(struct vm_area_struct *vma,
> unsigned long address, unsigned long end, pgprot_t newprot)
> diff --git v4.0-rc6.orig/mm/hugetlb.c v4.0-rc6/mm/hugetlb.c
> index 05e0233d30d7..8e1c46affc59 100644
> --- v4.0-rc6.orig/mm/hugetlb.c
> +++ v4.0-rc6/mm/hugetlb.c
> @@ -3795,20 +3795,6 @@ follow_huge_pud(struct mm_struct *mm, unsigned long address,
>
> #ifdef CONFIG_MEMORY_FAILURE
>
> -/* Should be called in hugetlb_lock */
> -static int is_hugepage_on_freelist(struct page *hpage)
> -{
> - struct page *page;
> - struct page *tmp;
> - struct hstate *h = page_hstate(hpage);
> - int nid = page_to_nid(hpage);
> -
> - list_for_each_entry_safe(page, tmp, &h->hugepage_freelists[nid], lru)
> - if (page == hpage)
> - return 1;
> - return 0;
> -}
> -
> /*
> * This function is called from memory failure code.
> * Assume the caller holds page lock of the head page.
> @@ -3820,7 +3806,11 @@ int dequeue_hwpoisoned_huge_page(struct page *hpage)
> int ret = -EBUSY;
>
> spin_lock(&hugetlb_lock);
> - if (is_hugepage_on_freelist(hpage)) {
> + /*
> + * Just checking !PageHugeActive is not enough, because that could be
> + * an isolated/hwpoisoned hugepage (which have >0 refcount).
> + */
> + if (!PageHugeActive(hpage) && !page_count(hpage)) {
> /*
> * Hwpoisoned hugepage isn't linked to activelist or freelist,
> * but dangling hpage->lru can trigger list-debug warnings
> @@ -3864,25 +3854,3 @@ void putback_active_hugepage(struct page *page)
> spin_unlock(&hugetlb_lock);
> put_page(page);
> }
> -
> -bool is_hugepage_active(struct page *page)
> -{
> - VM_BUG_ON_PAGE(!PageHuge(page), page);
> - /*
> - * This function can be called for a tail page because the caller,
> - * scan_movable_pages, scans through a given pfn-range which typically
> - * covers one memory block. In systems using gigantic hugepage (1GB
> - * for x86_64,) a hugepage is larger than a memory block, and we don't
> - * support migrating such large hugepages for now, so return false
> - * when called for tail pages.
> - */
> - if (PageTail(page))
> - return false;
> - /*
> - * Refcount of a hwpoisoned hugepages is 1, but they are not active,
> - * so we should return false for them.
> - */
> - if (unlikely(PageHWPoison(page)))
> - return false;
> - return page_count(page) > 0;
> -}
> diff --git v4.0-rc6.orig/mm/memory_hotplug.c v4.0-rc6/mm/memory_hotplug.c
> index 65842d688b7c..2d53388c0715 100644
> --- v4.0-rc6.orig/mm/memory_hotplug.c
> +++ v4.0-rc6/mm/memory_hotplug.c
> @@ -1376,7 +1376,7 @@ static unsigned long scan_movable_pages(unsigned long start, unsigned long end)
> if (PageLRU(page))
> return pfn;
> if (PageHuge(page)) {
> - if (is_hugepage_active(page))
> + if (PageHugeActive(page))
> return pfn;
> else
> pfn = round_up(pfn + 1,
> --
> 1.9.3
--
Michal Hocko
SUSE Labs
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