Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1603756

[tip:x86/mm] mm/gup: Move page table entry dereference into helper function

Show all headers | View raw

Commit-ID:  0005d20b2ff1e501e186b3b3bc587085ac305fdc
Gitweb:     http://git.kernel.org/tip/0005d20b2ff1e501e186b3b3bc587085ac305fdc
Author:     Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
AuthorDate: Thu, 16 Mar 2017 18:26:51 +0300
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Sat, 18 Mar 2017 09:48:02 +0100

mm/gup: Move page table entry dereference into helper function

This is a preparation patch for the transition of x86 to the generic GUP_fast()
implementation.

On x86 PAE, page table entry is larger than sizeof(long) and we would
need to provide a helper that can read the entry atomically.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Aneesh Kumar K . V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dann Frazier <dann.frazier@canonical.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Steve Capper <steve.capper@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Cc: linux-mm@kvack.org
Link: http://lkml.kernel.org/r/20170316152655.37789-4-kirill.shutemov@linux.intel.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 mm/gup.c | 20 ++++++++++++--------
 1 file changed, 12 insertions(+), 8 deletions(-)

diff --git a/mm/gup.c b/mm/gup.c
index a62a778c..e83db38 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1189,6 +1189,17 @@ struct page *get_dump_page(unsigned long addr)
  */
 #ifdef CONFIG_HAVE_GENERIC_RCU_GUP
 
+#ifndef gup_get_pte
+/*
+ * We assume that the PTE can be read atomically. If this is not the case for
+ * your architecture, please provide the helper.
+ */
+static inline pte_t gup_get_pte(pte_t *ptep)
+{
+	return READ_ONCE(*ptep);
+}
+#endif
+
 #ifdef __HAVE_ARCH_PTE_SPECIAL
 static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
 			 int write, struct page **pages, int *nr)
@@ -1198,14 +1209,7 @@ static int gup_pte_range(pmd_t pmd, unsigned long addr, unsigned long end,
 
 	ptem = ptep = pte_offset_map(&pmd, addr);
 	do {
-		/*
-		 * In the line below we are assuming that the pte can be read
-		 * atomically. If this is not the case for your architecture,
-		 * please wrap this in a helper function!
-		 *
-		 * for an example see gup_get_pte in arch/x86/mm/gup.c
-		 */
-		pte_t pte = READ_ONCE(*ptep);
+		pte_t pte = gup_get_pte(ptep);
 		struct page *head, *page;
 
 		/*

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH 0/7] Switch x86 to generic get_user_pages_fast() implementation "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-03-16 16:30 +0100
  [PATCH 3/7] mm/gup: Move page table entry dereference into helper "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-03-16 16:30 +0100
    [tip:x86/mm] mm/gup: Move page table entry dereference into helper  function "tip-bot for Kirill A. Shutemov" <tipbot@zytor.com> - 2017-03-18 11:00 +0100
  [PATCH 4/7] mm/gup: Make pages referenced during generic get_user_pages_fast() "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-03-16 16:30 +0100
    [tip:x86/mm] mm/gup: Mark all pages PageReferenced in generic  get_user_pages_fast() "tip-bot for Kirill A. Shutemov" <tipbot@zytor.com> - 2017-03-18 11:00 +0100
  [PATCH 7/7] x86/mm: Switch to generic get_user_page_fast() implementation "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-03-16 16:30 +0100
    Re: [PATCH 7/7] x86/mm: Switch to generic get_user_page_fast()  implementation Peter Zijlstra <peterz@infradead.org> - 2017-03-16 18:30 +0100
      Re: [PATCH 7/7] x86/mm: Switch to generic get_user_page_fast()  implementation "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2017-03-16 20:20 +0100
    [PATCHv2 7/7] x86/mm: Switch to generic get_user_page_fast() implementation "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-03-16 22:40 +0100
      Re: [PATCHv2 7/7] x86/mm: Switch to generic get_user_page_fast()  implementation "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-03-17 18:40 +0100
      [tip:x86/mm] x86/mm/gup: Switch GUP to the generic  get_user_page_fast() implementation "tip-bot for Kirill A. Shutemov" <tipbot@zytor.com> - 2017-03-18 12:50 +0100
  [PATCH 1/7] mm: Drop arch_pte_access_permitted() mmu hook "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> - 2017-03-16 16:40 +0100
    [tip:x86/mm] mm/gup: Drop the arch_pte_access_permitted() MMU  callback "tip-bot for Kirill A. Shutemov" <tipbot@zytor.com> - 2017-03-18 11:00 +0100
  Re: [PATCH 0/7] Switch x86 to generic get_user_pages_fast() implementation Linus Torvalds <torvalds@linux-foundation.org> - 2017-03-16 19:10 +0100
  Re: [PATCH 0/7] Switch x86 to generic get_user_pages_fast()  implementation Ingo Molnar <mingo@kernel.org> - 2017-03-17 09:40 +0100

csiph-web