Commit 4d7672b4 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Make sure we copy pages inserted with "vm_insert_page()" on fork 



The logic that decides that a fork() might be able to avoid copying a VM
area when it can be re-created by page faults didn't know about the new
vm_insert_page() case.

Also make some things a bit more anal wrt VM_PFNMAP.

Pointed out by Hugh Dickins <hugh@veritas.com>

Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent 281ab031

include/linux/mm.h

+1 −0
Original line number Diff line number Diff line
@@ -163,6 +163,7 @@ extern unsigned int kobjsize(const void *objp); 
#define VM_HUGETLB	0x00400000	/* Huge TLB Page VM */

#define VM_NONLINEAR	0x00800000	/* Is non-linear (remap_file_pages) */

#define VM_MAPPED_COPY	0x01000000	/* T if mapped copy of data (nommu mmap) */

#define VM_INSERTPAGE	0x02000000	/* The vma has had "vm_insert_page()" done on it */



#ifndef VM_STACK_DEFAULT_FLAGS		/* arch can override this */

#define VM_STACK_DEFAULT_FLAGS VM_DATA_DEFAULT_FLAGS

mm/memory.c

+2 −1
Original line number Diff line number Diff line
@@ -574,7 +574,7 @@ int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm, 
	 * readonly mappings. The tradeoff is that copy_page_range is more

	 * efficient than faulting.

	 */

	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP))) {

	if (!(vma->vm_flags & (VM_HUGETLB|VM_NONLINEAR|VM_PFNMAP|VM_INSERTPAGE))) {

		if (!vma->anon_vma)

			return 0;

	}
@@ -1228,6 +1228,7 @@ int vm_insert_page(struct vm_area_struct *vma, unsigned long addr, struct page * 
		return -EFAULT;

	if (!page_count(page))

		return -EINVAL;

	vma->vm_flags |= VM_INSERTPAGE;

	return insert_page(vma->vm_mm, addr, page, vma->vm_page_prot);

}

EXPORT_SYMBOL(vm_insert_page);

mm/mmap.c

+1 −1
Original line number Diff line number Diff line
@@ -611,7 +611,7 @@ again: remove_next = 1 + (end > next->vm_end); 
 * If the vma has a ->close operation then the driver probably needs to release

 * per-vma resources, so we don't attempt to merge those.

 */

#define VM_SPECIAL (VM_IO | VM_DONTCOPY | VM_DONTEXPAND | VM_RESERVED)

#define VM_SPECIAL (VM_IO | VM_DONTCOPY | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP)



static inline int is_mergeable_vma(struct vm_area_struct *vma,

			struct file *file, unsigned long vm_flags)

mm/mremap.c

+1 −1
Original line number Diff line number Diff line
@@ -323,7 +323,7 @@ unsigned long do_mremap(unsigned long addr, 
	/* We can't remap across vm area boundaries */

	if (old_len > vma->vm_end - addr)

		goto out;

	if (vma->vm_flags & VM_DONTEXPAND) {

	if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) {

		if (new_len > old_len)

			goto out;

	}

CRA Git | Maintained and supported by SUSTech CRA and CCSE