Commit 30c9f3a9 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Remove internal use of 'write_access' in mm/memory.c 



The fault handling routines really want more fine-grained flags than a
single "was it a write fault" boolean - the callers will want to set
flags like "you can return a retry error" etc.

And that's actually how the VM works internally, but right now the
top-level fault handling functions in mm/memory.c all pass just the
'write_access' boolean around.

This switches them over to pass around the FAULT_FLAG_xyzzy 'flags'
variable instead.  The 'write_access' calling convention still exists
for the exported 'handle_mm_fault()' function, but that is next.

Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 232086b1

mm/memory.c

+21 −21
Original line number Diff line number Diff line
@@ -2496,7 +2496,7 @@ int vmtruncate_range(struct inode *inode, loff_t offset, loff_t end) 
 */

static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,

		unsigned long address, pte_t *page_table, pmd_t *pmd,

		int write_access, pte_t orig_pte)

		unsigned int flags, pte_t orig_pte)

{

	spinlock_t *ptl;

	struct page *page;
@@ -2572,9 +2572,9 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, 


	inc_mm_counter(mm, anon_rss);

	pte = mk_pte(page, vma->vm_page_prot);

	if (write_access && reuse_swap_page(page)) {

	if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {

		pte = maybe_mkwrite(pte_mkdirty(pte), vma);

		write_access = 0;

		flags &= ~FAULT_FLAG_WRITE;

	}

	flush_icache_page(vma, page);

	set_pte_at(mm, address, page_table, pte);
@@ -2587,7 +2587,7 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma, 
		try_to_free_swap(page);

	unlock_page(page);



	if (write_access) {

	if (flags & FAULT_FLAG_WRITE) {

		ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);

		if (ret & VM_FAULT_ERROR)

			ret &= VM_FAULT_ERROR;
@@ -2616,7 +2616,7 @@ out_page: 
 */

static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,

		unsigned long address, pte_t *page_table, pmd_t *pmd,

		int write_access)

		unsigned int flags)

{

	struct page *page;

	spinlock_t *ptl;
@@ -2776,7 +2776,7 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma, 
	 * due to the bad i386 page protection. But it's valid

	 * for other architectures too.

	 *

	 * Note that if write_access is true, we either now have

	 * Note that if FAULT_FLAG_WRITE is set, we either now have

	 * an exclusive copy of the page, or this is a shared mapping,

	 * so we can make it writable and dirty to avoid having to

	 * handle that later.
@@ -2847,11 +2847,10 @@ unwritable_page: 


static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,

		unsigned long address, pte_t *page_table, pmd_t *pmd,

		int write_access, pte_t orig_pte)

		unsigned int flags, pte_t orig_pte)

{

	pgoff_t pgoff = (((address & PAGE_MASK)

			- vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;

	unsigned int flags = (write_access ? FAULT_FLAG_WRITE : 0);



	pte_unmap(page_table);

	return __do_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
@@ -2868,12 +2867,12 @@ static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 
 */

static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,

		unsigned long address, pte_t *page_table, pmd_t *pmd,

		int write_access, pte_t orig_pte)

		unsigned int flags, pte_t orig_pte)

{

	unsigned int flags = FAULT_FLAG_NONLINEAR |

				(write_access ? FAULT_FLAG_WRITE : 0);

	pgoff_t pgoff;



	flags |= FAULT_FLAG_NONLINEAR;



	if (!pte_unmap_same(mm, pmd, page_table, orig_pte))

		return 0;
@@ -2904,7 +2903,7 @@ static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 
 */

static inline int handle_pte_fault(struct mm_struct *mm,

		struct vm_area_struct *vma, unsigned long address,

		pte_t *pte, pmd_t *pmd, int write_access)

		pte_t *pte, pmd_t *pmd, unsigned int flags)

{

	pte_t entry;

	spinlock_t *ptl;
@@ -2915,30 +2914,30 @@ static inline int handle_pte_fault(struct mm_struct *mm, 
			if (vma->vm_ops) {

				if (likely(vma->vm_ops->fault))

					return do_linear_fault(mm, vma, address,

						pte, pmd, write_access, entry);

						pte, pmd, flags, entry);

			}

			return do_anonymous_page(mm, vma, address,

						 pte, pmd, write_access);

						 pte, pmd, flags);

		}

		if (pte_file(entry))

			return do_nonlinear_fault(mm, vma, address,

					pte, pmd, write_access, entry);

					pte, pmd, flags, entry);

		return do_swap_page(mm, vma, address,

					pte, pmd, write_access, entry);

					pte, pmd, flags, entry);

	}



	ptl = pte_lockptr(mm, pmd);

	spin_lock(ptl);

	if (unlikely(!pte_same(*pte, entry)))

		goto unlock;

	if (write_access) {

	if (flags & FAULT_FLAG_WRITE) {

		if (!pte_write(entry))

			return do_wp_page(mm, vma, address,

					pte, pmd, ptl, entry);

		entry = pte_mkdirty(entry);

	}

	entry = pte_mkyoung(entry);

	if (ptep_set_access_flags(vma, address, pte, entry, write_access)) {

	if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {

		update_mmu_cache(vma, address, entry);

	} else {

		/*
@@ -2947,7 +2946,7 @@ static inline int handle_pte_fault(struct mm_struct *mm, 
		 * This still avoids useless tlb flushes for .text page faults

		 * with threads.

		 */

		if (write_access)

		if (flags & FAULT_FLAG_WRITE)

			flush_tlb_page(vma, address);

	}

unlock:
@@ -2965,13 +2964,14 @@ int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 
	pud_t *pud;

	pmd_t *pmd;

	pte_t *pte;

	unsigned int flags = write_access ? FAULT_FLAG_WRITE : 0;



	__set_current_state(TASK_RUNNING);



	count_vm_event(PGFAULT);



	if (unlikely(is_vm_hugetlb_page(vma)))

		return hugetlb_fault(mm, vma, address, write_access);

		return hugetlb_fault(mm, vma, address, flags);



	pgd = pgd_offset(mm, address);

	pud = pud_alloc(mm, pgd, address);
@@ -2984,7 +2984,7 @@ int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, 
	if (!pte)

		return VM_FAULT_OOM;



	return handle_pte_fault(mm, vma, address, pte, pmd, write_access);

	return handle_pte_fault(mm, vma, address, pte, pmd, flags);

}



#ifndef __PAGETABLE_PUD_FOLDED

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