Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit ec47c3b9 authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds
Browse files

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: default avatarKirill 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e655fb29

mm/memory.c

+62 −0
Original line number Original line Diff line number Diff line
@@ -3354,6 +3354,62 @@ static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma, 
	return ret;

	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

 * do_fault() tries to create a new page mapping. It aggressively

 * tries to share with existing pages, but makes a separate copy if

 * 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))

	if (!(flags & FAULT_FLAG_WRITE))

		return do_read_fault(mm, vma, address, pmd, pgoff, flags,

		return do_read_fault(mm, vma, address, pmd, pgoff, flags,

				orig_pte);

				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);

	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))

	if (!(flags & FAULT_FLAG_WRITE))

		return do_read_fault(mm, vma, address, pmd, pgoff, flags,

		return do_read_fault(mm, vma, address, pmd, pgoff, flags,

				orig_pte);

				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);

	return do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);

}

}