The patch titled
mm: ZERO_PAGE without PTE_SPECIAL
has been added to the -mm tree. Its filename is
mm-zero_page-without-pte_special.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: mm: ZERO_PAGE without PTE_SPECIAL
From: Hugh Dickins <hugh.dickins@xxxxxxxxxxxxx>
Reinstate anonymous use of ZERO_PAGE to all architectures, not just to
those which __HAVE_ARCH_PTE_SPECIAL: as suggested by Nick Piggin.
Contrary to how I'd imagined it, there's nothing ugly about this, just a
zero_pfn test built into one or another block of vm_normal_page().
But the MIPS ZERO_PAGE-of-many-colours case demands is_zero_pfn() and
my_zero_pfn() inlines. Reinstate its mremap move_pte() shuffling of
ZERO_PAGEs we did from 2.6.17 to 2.6.19? Not unless someone shouts for
that: it would have to take vm_flags to weed out some cases.
Signed-off-by: Hugh Dickins <hugh.dickins@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx>
Cc: Nick Piggin <npiggin@xxxxxxx>
Cc: Mel Gorman <mel@xxxxxxxxx>
Cc: Minchan Kim <minchan.kim@xxxxxxxxx>
Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/mips/include/asm/pgtable.h | 14 +++++++++++
mm/memory.c | 36 ++++++++++++++++++++----------
2 files changed, 39 insertions(+), 11 deletions(-)
diff -puN arch/mips/include/asm/pgtable.h~mm-zero_page-without-pte_special arch/mips/include/asm/pgtable.h
--- a/arch/mips/include/asm/pgtable.h~mm-zero_page-without-pte_special
+++ a/arch/mips/include/asm/pgtable.h
@@ -76,6 +76,20 @@ extern unsigned long zero_page_mask;
#define ZERO_PAGE(vaddr) \
(virt_to_page((void *)(empty_zero_page + (((unsigned long)(vaddr)) & zero_page_mask))))
+#define is_zero_pfn is_zero_pfn
+static inline int is_zero_pfn(unsigned long pfn)
+{
+ extern unsigned long zero_pfn;
+ unsigned long offset_from_zero_pfn = pfn - zero_pfn;
+ return offset_from_zero_pfn <= (zero_page_mask >> PAGE_SHIFT);
+}
+
+#define my_zero_pfn my_zero_pfn
+static inline unsigned long my_zero_pfn(unsigned long addr)
+{
+ return page_to_pfn(ZERO_PAGE(addr));
+}
+
extern void paging_init(void);
/*
diff -puN mm/memory.c~mm-zero_page-without-pte_special mm/memory.c
--- a/mm/memory.c~mm-zero_page-without-pte_special
+++ a/mm/memory.c
@@ -107,7 +107,7 @@ static int __init disable_randmaps(char
}
__setup("norandmaps", disable_randmaps);
-static unsigned long zero_pfn __read_mostly;
+unsigned long zero_pfn __read_mostly;
/*
* CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
@@ -455,6 +455,20 @@ static inline int is_cow_mapping(unsigne
return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
}
+#ifndef is_zero_pfn
+static inline int is_zero_pfn(unsigned long pfn)
+{
+ return pfn == zero_pfn;
+}
+#endif
+
+#ifndef my_zero_pfn
+static inline unsigned long my_zero_pfn(unsigned long addr)
+{
+ return zero_pfn;
+}
+#endif
+
/*
* vm_normal_page -- This function gets the "struct page" associated with a pte.
*
@@ -512,7 +526,7 @@ struct page *vm_normal_page(struct vm_ar
goto check_pfn;
if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
return NULL;
- if (pfn != zero_pfn)
+ if (!is_zero_pfn(pfn))
print_bad_pte(vma, addr, pte, NULL);
return NULL;
}
@@ -534,6 +548,8 @@ struct page *vm_normal_page(struct vm_ar
}
}
+ if (is_zero_pfn(pfn))
+ return NULL;
check_pfn:
if (unlikely(pfn > highest_memmap_pfn)) {
print_bad_pte(vma, addr, pte, NULL);
@@ -1161,7 +1177,7 @@ struct page *follow_page(struct vm_area_
page = vm_normal_page(vma, address, pte);
if (unlikely(!page)) {
if ((flags & FOLL_DUMP) ||
- pte_pfn(pte) != zero_pfn)
+ !is_zero_pfn(pte_pfn(pte)))
goto bad_page;
page = pte_page(pte);
}
@@ -1444,10 +1460,6 @@ struct page *get_dump_page(unsigned long
if (__get_user_pages(current, current->mm, addr, 1,
FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma) < 1)
return NULL;
- if (page == ZERO_PAGE(0)) {
- page_cache_release(page);
- return NULL;
- }
flush_cache_page(vma, addr, page_to_pfn(page));
return page;
}
@@ -1630,7 +1642,8 @@ int vm_insert_mixed(struct vm_area_struc
* If we don't have pte special, then we have to use the pfn_valid()
* based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
* refcount the page if pfn_valid is true (hence insert_page rather
- * than insert_pfn).
+ * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
+ * without pte special, it would there be refcounted as a normal page.
*/
if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
struct page *page;
@@ -2098,7 +2111,7 @@ gotten:
if (unlikely(anon_vma_prepare(vma)))
goto oom;
- if (pte_pfn(orig_pte) == zero_pfn) {
+ if (is_zero_pfn(pte_pfn(orig_pte))) {
new_page = alloc_zeroed_user_highpage_movable(vma, address);
if (!new_page)
goto oom;
@@ -2613,8 +2626,9 @@ static int do_anonymous_page(struct mm_s
spinlock_t *ptl;
pte_t entry;
- if (HAVE_PTE_SPECIAL && !(flags & FAULT_FLAG_WRITE)) {
- entry = pte_mkspecial(pfn_pte(zero_pfn, vma->vm_page_prot));
+ if (!(flags & FAULT_FLAG_WRITE)) {
+ entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
+ vma->vm_page_prot));
ptl = pte_lockptr(mm, pmd);
spin_lock(ptl);
if (!pte_none(*page_table))
_
Patches currently in -mm which might be from hugh.dickins@xxxxxxxxxxxxx are
origin.patch
linux-next.patch
vfs-optimize-touch_time-too-fix.patch
fs-new-truncate-helpers.patch
fs-use-new-truncate-helpers.patch
fs-introduce-new-truncate-sequence.patch
fs-convert-simple-fs-to-new-truncate.patch
tmpfs-convert-to-use-the-new-truncate-convention.patch
ext2-convert-to-use-the-new-truncate-convention.patch
fat-convert-to-use-the-new-truncate-convention.patch
btrfs-convert-to-use-the-new-truncate-convention.patch
jfs-convert-to-use-the-new-truncate-convention.patch
udf-convert-to-use-the-new-truncate-convention.patch
minix-convert-to-use-the-new-truncate-convention.patch
vfs-seq_file-add-helpers-for-data-filling.patch
vfs-revert-proc-mounts-to-old-behavior-for-unreachable-mountpoints.patch
vfs-no-unreachable-prefix-for-sysvipc-maps-in-proc-pid-maps.patch
mm-oom-analysis-add-shmem-vmstat.patch
mm-vmstat-add-isolate-pages.patch
ksm-add-mmu_notifier-set_pte_at_notify.patch
ksm-first-tidy-up-madvise_vma.patch
ksm-define-madv_mergeable-and-madv_unmergeable.patch
ksm-the-mm-interface-to-ksm.patch
ksm-no-debug-in-page_dup_rmap.patch
ksm-identify-pageksm-pages.patch
ksm-kernel-samepage-merging.patch
ksm-prevent-mremap-move-poisoning.patch
ksm-change-copyright-message.patch
ksm-change-ksm-nice-level-to-be-5.patch
ksm-rename-kernel_pages_allocated.patch
ksm-move-pages_sharing-updates.patch
ksm-pages_unshared-and-pages_volatile.patch
ksm-break-cow-once-unshared.patch
ksm-keep-quiet-while-list-empty.patch
ksm-five-little-cleanups.patch
ksm-fix-endless-loop-on-oom.patch
ksm-distribute-remove_mm_from_lists.patch
ksm-fix-oom-deadlock.patch
ksm-fix-deadlock-with-munlock-in-exit_mmap.patch
ksm-sysfs-and-defaults.patch
ksm-add-some-documentation.patch
ksm-remove-vm_mergeable_flags.patch
ksm-clean-up-obsolete-references.patch
ksm-unmerge-is-an-origin-of-ooms.patch
ksm-mremap-use-err-from-ksm_madvise.patch
mm-add_to_swap_cache-must-not-sleep.patch
mm-add_to_swap_cache-does-not-return-eexist.patch
mm-includecheck-fix-for-mm-shmemc.patch
mm-introduce-page_lru_base_type-fix.patch
mm-replace-various-uses-of-num_physpages-by-totalram_pages.patch
hugetlbfs-allow-the-creation-of-files-suitable-for-map_private-on-the-vfs-internal-mount.patch
mm-munlock-use-follow_page.patch
mm-remove-unused-gup-flags.patch
mm-add-get_dump_page.patch
mm-foll_dump-replace-foll_anon.patch
mm-follow_hugetlb_page-flags.patch
mm-fix-anonymous-dirtying.patch
mm-reinstate-zero_page.patch
mm-foll-flags-for-gup-flags.patch
mm-munlock-avoid-zero_page.patch
mm-hugetlbfs_pagecache_present.patch
mm-zero_page-without-pte_special.patch
mm-zero_page-without-pte_special-mips-fix.patch
mm-move-highest_memmap_pfn.patch
mmap-remove-unnecessary-code.patch
tmpfs-depend-on-shmem.patch
mmap-avoid-unnecessary-anon_vma-lock-acquisition-in-vma_adjust.patch
mmap-avoid-unnecessary-anon_vma-lock-acquisition-in-vma_adjust-tweak.patch
mmap-save-some-cycles-for-the-shared-anonymous-mapping.patch
getrusage-fill-ru_maxrss-value.patch
getrusage-fill-ru_maxrss-value-update.patch
walk-system-ram-range-fix.patch
ramfs-move-ramfs_magic-to-include-linux-magich.patch
memory-controller-soft-limit-organize-cgroups-v9-fix.patch
prio_tree-debugging-patch.patch
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