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Commit 9b4bdd2f authored by Kirill A. Shutemov's avatar Kirill A. Shutemov Committed by Linus Torvalds
Browse files

mm: drop support of non-linear mapping from fault codepath 



We don't create non-linear mappings anymore.  Let's drop code which
handles them on page fault.

Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8a5f14a2

include/linux/mm.h

+7 −9
Original line number Diff line number Diff line
@@ -206,21 +206,19 @@ extern unsigned int kobjsize(const void *objp); 
extern pgprot_t protection_map[16];



#define FAULT_FLAG_WRITE	0x01	/* Fault was a write access */

#define FAULT_FLAG_NONLINEAR	0x02	/* Fault was via a nonlinear mapping */

#define FAULT_FLAG_MKWRITE	0x04	/* Fault was mkwrite of existing pte */

#define FAULT_FLAG_ALLOW_RETRY	0x08	/* Retry fault if blocking */

#define FAULT_FLAG_RETRY_NOWAIT	0x10	/* Don't drop mmap_sem and wait when retrying */

#define FAULT_FLAG_KILLABLE	0x20	/* The fault task is in SIGKILL killable region */

#define FAULT_FLAG_TRIED	0x40	/* second try */

#define FAULT_FLAG_USER		0x80	/* The fault originated in userspace */

#define FAULT_FLAG_MKWRITE	0x02	/* Fault was mkwrite of existing pte */

#define FAULT_FLAG_ALLOW_RETRY	0x04	/* Retry fault if blocking */

#define FAULT_FLAG_RETRY_NOWAIT	0x08	/* Don't drop mmap_sem and wait when retrying */

#define FAULT_FLAG_KILLABLE	0x10	/* The fault task is in SIGKILL killable region */

#define FAULT_FLAG_TRIED	0x20	/* Second try */

#define FAULT_FLAG_USER		0x40	/* The fault originated in userspace */



/*

 * vm_fault is filled by the the pagefault handler and passed to the vma's

 * ->fault function. The vma's ->fault is responsible for returning a bitmask

 * of VM_FAULT_xxx flags that give details about how the fault was handled.

 *

 * pgoff should be used in favour of virtual_address, if possible. If pgoff

 * is used, one may implement ->remap_pages to get nonlinear mapping support.

 * pgoff should be used in favour of virtual_address, if possible.

 */

struct vm_fault {

	unsigned int flags;		/* FAULT_FLAG_xxx flags */

mm/memory.c

+9 −56
Original line number Diff line number Diff line
@@ -1899,12 +1899,11 @@ int apply_to_page_range(struct mm_struct *mm, unsigned long addr, 
EXPORT_SYMBOL_GPL(apply_to_page_range);



/*

 * handle_pte_fault chooses page fault handler according to an entry

 * which was read non-atomically.  Before making any commitment, on

 * those architectures or configurations (e.g. i386 with PAE) which

 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault

 * must check under lock before unmapping the pte and proceeding

 * (but do_wp_page is only called after already making such a check;

 * handle_pte_fault chooses page fault handler according to an entry which was

 * read non-atomically.  Before making any commitment, on those architectures

 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched

 * parts, do_swap_page must check under lock before unmapping the pte and

 * proceeding (but do_wp_page is only called after already making such a check;

 * and do_anonymous_page can safely check later on).

 */

static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
@@ -2710,8 +2709,6 @@ void do_set_pte(struct vm_area_struct *vma, unsigned long address, 
	entry = mk_pte(page, vma->vm_page_prot);

	if (write)

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

	else if (pte_file(*pte) && pte_file_soft_dirty(*pte))

		entry = pte_mksoft_dirty(entry);

	if (anon) {

		inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);

		page_add_new_anon_rmap(page, vma, address);
@@ -2846,8 +2843,7 @@ static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma, 
	 * if page by the offset is not ready to be mapped (cold cache or

	 * something).

	 */

	if (vma->vm_ops->map_pages && !(flags & FAULT_FLAG_NONLINEAR) &&

	    fault_around_bytes >> PAGE_SHIFT > 1) {

	if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {

		pte = pte_offset_map_lock(mm, pmd, address, &ptl);

		do_fault_around(vma, address, pte, pgoff, flags);

		if (!pte_same(*pte, orig_pte))
@@ -2992,7 +2988,7 @@ static int do_shared_fault(struct mm_struct *mm, struct vm_area_struct *vma, 
 * The mmap_sem may have been released depending on flags and our

 * return value.  See filemap_fault() and __lock_page_or_retry().

 */

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

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

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

		unsigned int flags, pte_t orig_pte)

{
@@ -3009,46 +3005,6 @@ static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma, 
	return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);

}



/*

 * Fault of a previously existing named mapping. Repopulate the pte

 * from the encoded file_pte if possible. This enables swappable

 * nonlinear vmas.

 *

 * We enter with non-exclusive mmap_sem (to exclude vma changes,

 * but allow concurrent faults), and pte mapped but not yet locked.

 * We return with pte unmapped and unlocked.

 * The mmap_sem may have been released depending on flags and our

 * return value.  See filemap_fault() and __lock_page_or_retry().

 */

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

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

		unsigned int flags, pte_t orig_pte)

{

	pgoff_t pgoff;



	flags |= FAULT_FLAG_NONLINEAR;



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

		return 0;



	if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {

		/*

		 * Page table corrupted: show pte and kill process.

		 */

		print_bad_pte(vma, address, orig_pte, NULL);

		return VM_FAULT_SIGBUS;

	}



	pgoff = pte_to_pgoff(orig_pte);

	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_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);

}



static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,

				unsigned long addr, int page_nid,

				int *flags)
@@ -3176,15 +3132,12 @@ static int handle_pte_fault(struct mm_struct *mm, 
		if (pte_none(entry)) {

			if (vma->vm_ops) {

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

					return do_linear_fault(mm, vma, address,

						pte, pmd, flags, entry);

					return do_fault(mm, vma, address, pte,

							pmd, flags, entry);

			}

			return do_anonymous_page(mm, vma, address,

						 pte, pmd, flags);

		}

		if (pte_file(entry))

			return do_nonlinear_fault(mm, vma, address,

					pte, pmd, flags, entry);

		return do_swap_page(mm, vma, address,

					pte, pmd, flags, entry);

	}