Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932483Ab3CSAIL (ORCPT ); Mon, 18 Mar 2013 20:08:11 -0400 Received: from mx1.redhat.com ([209.132.183.28]:7585 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932378Ab3CSAIJ (ORCPT ); Mon, 18 Mar 2013 20:08:09 -0400 Date: Mon, 18 Mar 2013 20:07:16 -0400 From: Naoya Horiguchi To: Michal Hocko Cc: linux-mm@kvack.org, Andrew Morton , Mel Gorman , Hugh Dickins , KOSAKI Motohiro , Andi Kleen , linux-kernel@vger.kernel.org Message-ID: <1363651636-3lsf20se-mutt-n-horiguchi@ah.jp.nec.com> In-Reply-To: <20130318154057.GS10192@dhcp22.suse.cz> References: <1361475708-25991-1-git-send-email-n-horiguchi@ah.jp.nec.com> <1361475708-25991-6-git-send-email-n-horiguchi@ah.jp.nec.com> <20130318154057.GS10192@dhcp22.suse.cz> Subject: Re: [PATCH 5/9] migrate: enable migrate_pages() to migrate hugepage Mime-Version: 1.0 Content-Type: text/plain; charset=iso-2022-jp Content-Transfer-Encoding: 7bit Content-Disposition: inline X-Mutt-References: <20130318154057.GS10192@dhcp22.suse.cz> X-Mutt-Fcc: ~/Maildir/sent/ User-Agent: Mutt 1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5574 Lines: 148 On Mon, Mar 18, 2013 at 04:40:57PM +0100, Michal Hocko wrote: > On Thu 21-02-13 14:41:44, Naoya Horiguchi wrote: > > This patch extends check_range() to handle vma with VM_HUGETLB set. > > With this changes, we can migrate hugepage with migrate_pages(2). > > Note that for larger hugepages (covered by pud entries, 1GB for > > x86_64 for example), we simply skip it now. > > > > Signed-off-by: Naoya Horiguchi > > --- > > include/linux/hugetlb.h | 6 ++++-- > > mm/hugetlb.c | 10 ++++++++++ > > mm/mempolicy.c | 46 ++++++++++++++++++++++++++++++++++------------ > > 3 files changed, 48 insertions(+), 14 deletions(-) > > > > diff --git v3.8.orig/include/linux/hugetlb.h v3.8/include/linux/hugetlb.h > > index 8f87115..eb33df5 100644 > > --- v3.8.orig/include/linux/hugetlb.h > > +++ v3.8/include/linux/hugetlb.h > > @@ -69,6 +69,7 @@ void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed); > > int dequeue_hwpoisoned_huge_page(struct page *page); > > void putback_active_hugepage(struct page *page); > > void putback_active_hugepages(struct list_head *l); > > +void migrate_hugepage_add(struct page *page, struct list_head *list); > > void copy_huge_page(struct page *dst, struct page *src); > > > > extern unsigned long hugepages_treat_as_movable; > > @@ -88,8 +89,8 @@ struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address, > > pmd_t *pmd, int write); > > struct page *follow_huge_pud(struct mm_struct *mm, unsigned long address, > > pud_t *pud, int write); > > -int pmd_huge(pmd_t pmd); > > -int pud_huge(pud_t pmd); > > +extern int pmd_huge(pmd_t pmd); > > +extern int pud_huge(pud_t pmd); > > extern is not needed here. OK. > > unsigned long hugetlb_change_protection(struct vm_area_struct *vma, > > unsigned long address, unsigned long end, pgprot_t newprot); > > > > @@ -134,6 +135,7 @@ static inline int dequeue_hwpoisoned_huge_page(struct page *page) > > > > #define putback_active_hugepage(p) 0 > > #define putback_active_hugepages(l) 0 > > +#define migrate_hugepage_add(p, l) 0 > > static inline void copy_huge_page(struct page *dst, struct page *src) > > { > > } > > diff --git v3.8.orig/mm/hugetlb.c v3.8/mm/hugetlb.c > > index cb9d43b8..86ffcb7 100644 > > --- v3.8.orig/mm/hugetlb.c > > +++ v3.8/mm/hugetlb.c > > @@ -3202,3 +3202,13 @@ void putback_active_hugepages(struct list_head *l) > > list_for_each_entry_safe(page, page2, l, lru) > > putback_active_hugepage(page); > > } > > + > > +void migrate_hugepage_add(struct page *page, struct list_head *list) > > +{ > > + VM_BUG_ON(!PageHuge(page)); > > + get_page(page); > > + spin_lock(&hugetlb_lock); > > Why hugetlb_lock? Comment for this lock says that it protects > hugepage_freelists, nr_huge_pages, and free_huge_pages. I think that this comment is out of date and hugepage_activelists, which was introduced recently, should be protected because this patchset adds is_hugepage_movable() which runs through the list. So I'll update the comment in the next post. > > + list_move_tail(&page->lru, list); > > + spin_unlock(&hugetlb_lock); > > + return; > > +} > > diff --git v3.8.orig/mm/mempolicy.c v3.8/mm/mempolicy.c > > index e2df1c1..8627135 100644 > > --- v3.8.orig/mm/mempolicy.c > > +++ v3.8/mm/mempolicy.c > > @@ -525,6 +525,27 @@ static int check_pte_range(struct vm_area_struct *vma, pmd_t *pmd, > > return addr != end; > > } > > > > +static void check_hugetlb_pmd_range(struct vm_area_struct *vma, pmd_t *pmd, > > + const nodemask_t *nodes, unsigned long flags, > > + void *private) > > +{ > > +#ifdef CONFIG_HUGETLB_PAGE > > + int nid; > > + struct page *page; > > + > > + spin_lock(&vma->vm_mm->page_table_lock); > > + page = pte_page(huge_ptep_get((pte_t *)pmd)); > > + spin_unlock(&vma->vm_mm->page_table_lock); > > I am a bit confused why page_table_lock is used here and why it doesn't > cover the page usage. I expected this function to do the same for pmd as check_pte_range() does for pte, but the above code didn't do it. I should've put spin_unlock below migrate_hugepage_add(). Sorry for the confusion. > > + nid = page_to_nid(page); > > + if (node_isset(nid, *nodes) != !!(flags & MPOL_MF_INVERT) > > + && ((flags & MPOL_MF_MOVE && page_mapcount(page) == 1) > > + || flags & MPOL_MF_MOVE_ALL)) > > + migrate_hugepage_add(page, private); > > +#else > > + BUG(); > > +#endif > > +} > > + > > static inline int check_pmd_range(struct vm_area_struct *vma, pud_t *pud, > > unsigned long addr, unsigned long end, > > const nodemask_t *nodes, unsigned long flags, > > @@ -536,6 +557,11 @@ static inline int check_pmd_range(struct vm_area_struct *vma, pud_t *pud, > > pmd = pmd_offset(pud, addr); > > do { > > next = pmd_addr_end(addr, end); > > + if (pmd_huge(*pmd) && is_vm_hugetlb_page(vma)) { > > Why an explicit check for is_vm_hugetlb_page here? Isn't pmd_huge() > sufficient? I think we need both check here because if we use only pmd_huge(), pmd for thp goes into this branch wrongly. Thanks, Naoya > > + check_hugetlb_pmd_range(vma, pmd, nodes, > > + flags, private); > > + continue; > > + } > > split_huge_page_pmd(vma, addr, pmd); > > if (pmd_none_or_trans_huge_or_clear_bad(pmd)) > > continue; > [...] > -- > Michal Hocko > SUSE Labs -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/