From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e28smtp07.in.ibm.com (e28smtp07.in.ibm.com [122.248.162.7]) (using TLSv1 with cipher CAMELLIA256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id BA7E31A042B for ; Sat, 16 May 2015 01:42:48 +1000 (AEST) Received: from /spool/local by e28smtp07.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 15 May 2015 21:12:45 +0530 Received: from d28relay01.in.ibm.com (d28relay01.in.ibm.com [9.184.220.58]) by d28dlp03.in.ibm.com (Postfix) with ESMTP id E28B4125805E for ; Fri, 15 May 2015 21:14:56 +0530 (IST) Received: from d28av04.in.ibm.com (d28av04.in.ibm.com [9.184.220.66]) by d28relay01.in.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id t4FFghio47644826 for ; Fri, 15 May 2015 21:12:43 +0530 Received: from d28av04.in.ibm.com (localhost [127.0.0.1]) by d28av04.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id t4FFggM0019029 for ; Fri, 15 May 2015 21:12:43 +0530 From: "Aneesh Kumar K.V" To: akpm@linux-foundation.org, benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au, kirill.shutemov@linux.intel.com, aarcange@redhat.com, schwidefsky@de.ibm.com Subject: [PATCH V5 1/3] mm/thp: Split out pmd collpase flush into a separate functions Date: Fri, 15 May 2015 21:12:28 +0530 Message-Id: <1431704550-19937-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com> In-Reply-To: <1431704550-19937-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> References: <1431704550-19937-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Cc: linux-mm@kvack.org, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, "Aneesh Kumar K.V" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Architectures like ppc64 [1] need to do special things while clearing pmd before a collapse. For them this operation is largely different from a normal hugepage pte clear. Hence add a separate function to clear pmd before collapse. After this patch pmdp_* functions operate only on hugepage pte, and not on regular pmd_t values pointing to page table. [1] ppc64 needs to invalidate all the normal page pte mappings we already have inserted in the hardware hash page table. But before doing that we need to make sure there are no parallel hash page table insert going on. So we need to do a kick_all_cpus_sync() before flushing the older hash table entries. By moving this to a separate function we capture these details and mention how it is different from a hugepage pte clear. This patch is a cleanup and only does code movement for clarity. There should not be any change in functionality. Acked-by: Kirill A. Shutemov Signed-off-by: Aneesh Kumar K.V --- arch/powerpc/include/asm/pgtable-ppc64.h | 4 ++ arch/powerpc/mm/pgtable_64.c | 76 +++++++++++++++++--------------- include/asm-generic/pgtable.h | 22 +++++++++ mm/huge_memory.c | 2 +- 4 files changed, 68 insertions(+), 36 deletions(-) diff --git a/arch/powerpc/include/asm/pgtable-ppc64.h b/arch/powerpc/include/asm/pgtable-ppc64.h index 43e6ad424c7f..129c67ebc81a 100644 --- a/arch/powerpc/include/asm/pgtable-ppc64.h +++ b/arch/powerpc/include/asm/pgtable-ppc64.h @@ -576,6 +576,10 @@ static inline void pmdp_set_wrprotect(struct mm_struct *mm, unsigned long addr, extern void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address, pmd_t *pmdp); +extern pmd_t pmdp_collapse_flush(struct vm_area_struct *vma, + unsigned long address, pmd_t *pmdp); +#define pmdp_collapse_flush pmdp_collapse_flush + #define __HAVE_ARCH_PGTABLE_DEPOSIT extern void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp, pgtable_t pgtable); diff --git a/arch/powerpc/mm/pgtable_64.c b/arch/powerpc/mm/pgtable_64.c index 59daa5eeec25..9171c1a37290 100644 --- a/arch/powerpc/mm/pgtable_64.c +++ b/arch/powerpc/mm/pgtable_64.c @@ -560,41 +560,47 @@ pmd_t pmdp_clear_flush(struct vm_area_struct *vma, unsigned long address, pmd_t pmd; VM_BUG_ON(address & ~HPAGE_PMD_MASK); - if (pmd_trans_huge(*pmdp)) { - pmd = pmdp_get_and_clear(vma->vm_mm, address, pmdp); - } else { - /* - * khugepaged calls this for normal pmd - */ - pmd = *pmdp; - pmd_clear(pmdp); - /* - * Wait for all pending hash_page to finish. This is needed - * in case of subpage collapse. When we collapse normal pages - * to hugepage, we first clear the pmd, then invalidate all - * the PTE entries. The assumption here is that any low level - * page fault will see a none pmd and take the slow path that - * will wait on mmap_sem. But we could very well be in a - * hash_page with local ptep pointer value. Such a hash page - * can result in adding new HPTE entries for normal subpages. - * That means we could be modifying the page content as we - * copy them to a huge page. So wait for parallel hash_page - * to finish before invalidating HPTE entries. We can do this - * by sending an IPI to all the cpus and executing a dummy - * function there. - */ - kick_all_cpus_sync(); - /* - * Now invalidate the hpte entries in the range - * covered by pmd. This make sure we take a - * fault and will find the pmd as none, which will - * result in a major fault which takes mmap_sem and - * hence wait for collapse to complete. Without this - * the __collapse_huge_page_copy can result in copying - * the old content. - */ - flush_tlb_pmd_range(vma->vm_mm, &pmd, address); - } + VM_BUG_ON(!pmd_trans_huge(*pmdp)); + pmd = pmdp_get_and_clear(vma->vm_mm, address, pmdp); + return pmd; +} + +pmd_t pmdp_collapse_flush(struct vm_area_struct *vma, unsigned long address, + pmd_t *pmdp) +{ + pmd_t pmd; + + VM_BUG_ON(address & ~HPAGE_PMD_MASK); + VM_BUG_ON(pmd_trans_huge(*pmdp)); + + pmd = *pmdp; + pmd_clear(pmdp); + /* + * Wait for all pending hash_page to finish. This is needed + * in case of subpage collapse. When we collapse normal pages + * to hugepage, we first clear the pmd, then invalidate all + * the PTE entries. The assumption here is that any low level + * page fault will see a none pmd and take the slow path that + * will wait on mmap_sem. But we could very well be in a + * hash_page with local ptep pointer value. Such a hash page + * can result in adding new HPTE entries for normal subpages. + * That means we could be modifying the page content as we + * copy them to a huge page. So wait for parallel hash_page + * to finish before invalidating HPTE entries. We can do this + * by sending an IPI to all the cpus and executing a dummy + * function there. + */ + kick_all_cpus_sync(); + /* + * Now invalidate the hpte entries in the range + * covered by pmd. This make sure we take a + * fault and will find the pmd as none, which will + * result in a major fault which takes mmap_sem and + * hence wait for collapse to complete. Without this + * the __collapse_huge_page_copy can result in copying + * the old content. + */ + flush_tlb_pmd_range(vma->vm_mm, &pmd, address); return pmd; } diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index 39f1d6a2b04d..acdcaac77d93 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -189,6 +189,28 @@ extern void pmdp_splitting_flush(struct vm_area_struct *vma, unsigned long address, pmd_t *pmdp); #endif +#ifndef pmdp_collapse_flush +#define pmdp_collapse_flush pmdp_collapse_flush +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +static inline pmd_t pmdp_collapse_flush(struct vm_area_struct *vma, + unsigned long address, + pmd_t *pmdp) +{ + return pmdp_clear_flush(vma, address, pmdp); +} +#define pmdp_collapse_flush pmdp_collapse_flush +#else +static inline pmd_t pmdp_collapse_flush(struct vm_area_struct *vma, + unsigned long address, + pmd_t *pmdp) +{ + BUILD_BUG(); + return *pmdp; +} +#define pmdp_collapse_flush pmdp_collapse_flush +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ +#endif + #ifndef __HAVE_ARCH_PGTABLE_DEPOSIT extern void pgtable_trans_huge_deposit(struct mm_struct *mm, pmd_t *pmdp, pgtable_t pgtable); diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 078832cf3636..88f695a4e38b 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -2499,7 +2499,7 @@ static void collapse_huge_page(struct mm_struct *mm, * huge and small TLB entries for the same virtual address * to avoid the risk of CPU bugs in that area. */ - _pmd = pmdp_clear_flush(vma, address, pmd); + _pmd = pmdp_collapse_flush(vma, address, pmd); spin_unlock(pmd_ptl); mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end); -- 2.1.4