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From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
To: benh@kernel.crashing.org, paulus@samba.org
Cc: linuxppc-dev@lists.ozlabs.org,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Subject: [PATCH -V2 24/26] powerpc/THP: get_user_pages_fast changes
Date: Wed,  6 Mar 2013 11:40:25 +0530	[thread overview]
Message-ID: <1362550227-575-25-git-send-email-aneesh.kumar@linux.vnet.ibm.com> (raw)
In-Reply-To: <1362550227-575-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com>

From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>

handle large pages for get_user_pages_fast. Also take care of large page splitting.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
---
 arch/powerpc/mm/gup.c |   84 +++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 82 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/mm/gup.c b/arch/powerpc/mm/gup.c
index d7efdbf..835c1ae 100644
--- a/arch/powerpc/mm/gup.c
+++ b/arch/powerpc/mm/gup.c
@@ -55,6 +55,72 @@ static noinline int gup_pte_range(pmd_t pmd, unsigned long addr,
 	return 1;
 }
 
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+static inline int gup_huge_pmd(pmd_t *pmdp, unsigned long addr,
+			       unsigned long end, int write,
+			       struct page **pages, int *nr)
+{
+	int refs;
+	pmd_t pmd;
+	unsigned long mask;
+	struct page *head, *page, *tail;
+
+	pmd = *pmdp;
+	mask = PMD_HUGE_PRESENT | PMD_HUGE_USER;
+	if (write)
+		mask |= PMD_HUGE_RW;
+
+	if ((pmd_val(pmd) & mask) != mask)
+		return 0;
+
+	/* large pages are never "special" */
+	VM_BUG_ON(!pfn_valid(pmd_pfn(pmd)));
+
+	refs = 0;
+	head = pmd_page(pmd);
+	page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
+	tail = page;
+	do {
+		VM_BUG_ON(compound_head(page) != head);
+		pages[*nr] = page;
+		(*nr)++;
+		page++;
+		refs++;
+	} while (addr += PAGE_SIZE, addr != end);
+
+	if (!page_cache_add_speculative(head, refs)) {
+		*nr -= refs;
+		return 0;
+	}
+
+	if (unlikely(pmd_val(pmd) != pmd_val(*pmdp))) {
+		*nr -= refs;
+		while (refs--)
+			put_page(head);
+		return 0;
+	}
+	/*
+	 * Any tail page need their mapcount reference taken before we
+	 * return.
+	 */
+	while (refs--) {
+		if (PageTail(tail))
+			get_huge_page_tail(tail);
+		tail++;
+	}
+
+	return 1;
+}
+#else
+
+static inline int gup_huge_pmd(pmd_t *pmdp, unsigned long addr,
+			       unsigned long end, int write,
+			       struct page **pages, int *nr)
+{
+	return 1;
+}
+#endif
+
 static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
 		int write, struct page **pages, int *nr)
 {
@@ -66,9 +132,23 @@ static int gup_pmd_range(pud_t pud, unsigned long addr, unsigned long end,
 		pmd_t pmd = *pmdp;
 
 		next = pmd_addr_end(addr, end);
-		if (pmd_none(pmd))
+		/*
+		 * The pmd_trans_splitting() check below explains why
+		 * pmdp_splitting_flush has to flush the tlb, to stop
+		 * this gup-fast code from running while we set the
+		 * splitting bit in the pmd. Returning zero will take
+		 * the slow path that will call wait_split_huge_page()
+		 * if the pmd is still in splitting state. gup-fast
+		 * can't because it has irq disabled and
+		 * wait_split_huge_page() would never return as the
+		 * tlb flush IPI wouldn't run.
+		 */
+		if (pmd_none(pmd) || pmd_trans_splitting(pmd))
 			return 0;
-		if (is_hugepd(pmdp)) {
+		if (unlikely(pmd_large(pmd))) {
+			if (!gup_huge_pmd(pmdp, addr, next, write, pages, nr))
+				return 0;
+		} else if (is_hugepd(pmdp)) {
 			if (!gup_hugepd((hugepd_t *)pmdp, PMD_SHIFT,
 					addr, next, write, pages, nr))
 				return 0;
-- 
1.7.10

  parent reply	other threads:[~2013-03-06  6:11 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-06  6:10 [PATCH -V2 00/26]T HP support for PPC64 Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 01/26] powerpc: Use signed formatting when printing error Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 02/26] powerpc: Save DAR and DSISR in pt_regs on MCE Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 03/26] powerpc: Don't hard code the size of pte page Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 04/26] powerpc: Reduce the PTE_INDEX_SIZE Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 05/26] powerpc: Move the pte free routines from common header Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 06/26] powerpc: Reduce PTE table memory wastage Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 07/26] powerpc: Add size argument to pgtable_cache_add Aneesh Kumar K.V
2013-03-13  2:47   ` Paul Mackerras
2013-03-13  9:25     ` Aneesh Kumar K.V
2013-03-13 11:34       ` Paul Mackerras
2013-03-06  6:10 ` [PATCH -V2 08/26] powerpc: Clarify __pgtable_cache_add by renaming shift to index Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 09/26] powerpc: Use encode avpn where we need only avpn values Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 10/26] powerpc: Decode the pte-lp-encoding bits correctly Aneesh Kumar K.V
2013-03-13  4:09   ` Paul Mackerras
2013-03-06  6:10 ` [PATCH -V2 11/26] powerpc: Fix hpte_decode to use the correct decoding for page sizes Aneesh Kumar K.V
2013-03-13  2:56   ` Paul Mackerras
2013-03-06  6:10 ` [PATCH -V2 12/26] powerpc: Return all the valid pte ecndoing in KVM_PPC_GET_SMMU_INFO ioctl Aneesh Kumar K.V
2013-03-13  4:11   ` Paul Mackerras
2013-03-06  6:10 ` [PATCH -V2 13/26] powerpc: Update tlbie/tlbiel as per ISA doc Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 14/26] powerpc: print both base and actual page size on hash failure Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 15/26] powerpc: Print page size info during boot Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 16/26] mm/THP: HPAGE_SHIFT is not a #define on some arch Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 17/26] mm/THP: Add pmd args to pgtable deposit and withdraw APIs Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 18/26] mm/THP: withdraw the pgtable after pmdp related operations Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 19/26] powerpc/THP: Implement transparent huge pages for ppc64 Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 20/26] powerpc/THP: Differentiate THP PMD entries from HUGETLB PMD entries Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 21/26] powerpc/THP: Add code to handle HPTE faults for large pages Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 22/26] powerpc: Handle huge page in perf callchain Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 23/26] powerpc/THP: hypervisor require few WIMG bit set Aneesh Kumar K.V
2013-03-06  6:10 ` Aneesh Kumar K.V [this message]
2013-03-06  6:10 ` [PATCH -V2 25/26] powerpc/THP: Enable THP on PPC64 Aneesh Kumar K.V
2013-03-06  6:10 ` [PATCH -V2 26/26] powerpc: Optimize hugepage invalidate Aneesh Kumar K.V

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