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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2014-04-03 14:48:12 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-04-03 16:21:03 -0700
commitec47c3b9543054f6f255d027100fa8214e637003 (patch)
tree9f8a3b0ad6e2c8fe110a2c68ae960426067e1798 /mm/memory.c
parente655fb29074a7aa471bfc9f51a0139c6f636a649 (diff)
mm: introduce do_cow_fault()
Introduce do_cow_fault(). The function does what do_fault() does for write page faults to private mappings. Unlike do_fault(), do_read_fault() is relatively clean and straight-forward. Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Matthew Wilcox <matthew.r.wilcox@intel.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory.c')
-rw-r--r--mm/memory.c62
1 files changed, 62 insertions, 0 deletions
diff --git a/mm/memory.c b/mm/memory.c
index 56784e9a7151..5be13e794a7c 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3354,6 +3354,62 @@ static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma,
return ret;
}
+static int do_cow_fault(struct mm_struct *mm, struct vm_area_struct *vma,
+ unsigned long address, pmd_t *pmd,
+ pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
+{
+ struct page *fault_page, *new_page;
+ spinlock_t *ptl;
+ pte_t entry, *pte;
+ int ret;
+
+ if (unlikely(anon_vma_prepare(vma)))
+ return VM_FAULT_OOM;
+
+ new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
+ if (!new_page)
+ return VM_FAULT_OOM;
+
+ if (mem_cgroup_newpage_charge(new_page, mm, GFP_KERNEL)) {
+ page_cache_release(new_page);
+ return VM_FAULT_OOM;
+ }
+
+ ret = __do_fault(vma, address, pgoff, flags, &fault_page);
+ if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
+ goto uncharge_out;
+
+ copy_user_highpage(new_page, fault_page, address, vma);
+ __SetPageUptodate(new_page);
+
+ pte = pte_offset_map_lock(mm, pmd, address, &ptl);
+ if (unlikely(!pte_same(*pte, orig_pte))) {
+ pte_unmap_unlock(pte, ptl);
+ unlock_page(fault_page);
+ page_cache_release(fault_page);
+ goto uncharge_out;
+ }
+
+ flush_icache_page(vma, new_page);
+ entry = mk_pte(new_page, vma->vm_page_prot);
+ entry = maybe_mkwrite(pte_mkdirty(entry), vma);
+ inc_mm_counter_fast(mm, MM_ANONPAGES);
+ page_add_new_anon_rmap(new_page, vma, address);
+ set_pte_at(mm, address, pte, entry);
+
+ /* no need to invalidate: a not-present page won't be cached */
+ update_mmu_cache(vma, address, pte);
+
+ pte_unmap_unlock(pte, ptl);
+ unlock_page(fault_page);
+ page_cache_release(fault_page);
+ return ret;
+uncharge_out:
+ mem_cgroup_uncharge_page(new_page);
+ page_cache_release(new_page);
+ return ret;
+}
+
/*
* do_fault() tries to create a new page mapping. It aggressively
* tries to share with existing pages, but makes a separate copy if
@@ -3550,6 +3606,9 @@ static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
if (!(flags & FAULT_FLAG_WRITE))
return do_read_fault(mm, vma, address, pmd, pgoff, flags,
orig_pte);
+ if (!(vma->vm_flags & VM_SHARED))
+ return do_cow_fault(mm, vma, address, pmd, pgoff, flags,
+ orig_pte);
return do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
}
@@ -3585,6 +3644,9 @@ static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
if (!(flags & FAULT_FLAG_WRITE))
return do_read_fault(mm, vma, address, pmd, pgoff, flags,
orig_pte);
+ if (!(vma->vm_flags & VM_SHARED))
+ return do_cow_fault(mm, vma, address, pmd, pgoff, flags,
+ orig_pte);
return do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
}