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Commit 05b74384 authored by Prasanna Meda's avatar Prasanna Meda Committed by Linus Torvalds
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[PATCH] madvise: merge the maps 



This attempts to merge back the split maps.  This code is mostly copied
from Chrisw's mlock merging from post 2.6.11 trees.  The only difference is
in munmapped_error handling.  Also passed prev to willneed/dontneed,
eventhogh they do not handle it now, since I felt it will be cleaner,
instead of handling prev in madvise_vma in some cases and in subfunction in
some cases.

Signed-off-by: default avatarPrasanna Meda <pmeda@akamai.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent e798c6e8

mm/madvise.c

+51 −29
Original line number Diff line number Diff line
@@ -8,17 +8,20 @@ 
#include <linux/mman.h>

#include <linux/pagemap.h>

#include <linux/syscalls.h>

#include <linux/mempolicy.h>

#include <linux/hugetlb.h>



/*

 * We can potentially split a vm area into separate

 * areas, each area with its own behavior.

 */

static long madvise_behavior(struct vm_area_struct * vma, unsigned long start,

			     unsigned long end, int behavior)

static long madvise_behavior(struct vm_area_struct * vma,

		     struct vm_area_struct **prev,

		     unsigned long start, unsigned long end, int behavior)

{

	struct mm_struct * mm = vma->vm_mm;

	int error = 0;

	pgoff_t pgoff;

	int new_flags = vma->vm_flags & ~VM_READHINTMASK;



	switch (behavior) {
@@ -32,8 +35,20 @@ static long madvise_behavior(struct vm_area_struct * vma, unsigned long start, 
		break;

	}



	if (new_flags == vma->vm_flags)

		goto out;

	if (new_flags == vma->vm_flags) {

		*prev = vma;

		goto success;

	}



	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);

	*prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,

				vma->vm_file, pgoff, vma_policy(vma));

	if (*prev) {

		vma = *prev;

		goto success;

	}



	*prev = vma;



	if (start != vma->vm_start) {

		error = split_vma(mm, vma, start, 1);
@@ -56,6 +71,7 @@ static long madvise_behavior(struct vm_area_struct * vma, unsigned long start, 
out:

	if (error == -ENOMEM)

		error = -EAGAIN;

success:

	return error;

}
@@ -63,6 +79,7 @@ static long madvise_behavior(struct vm_area_struct * vma, unsigned long start, 
 * Schedule all required I/O operations.  Do not wait for completion.

 */

static long madvise_willneed(struct vm_area_struct * vma,

			     struct vm_area_struct ** prev,

			     unsigned long start, unsigned long end)

{

	struct file *file = vma->vm_file;
@@ -70,6 +87,7 @@ static long madvise_willneed(struct vm_area_struct * vma, 
	if (!file)

		return -EBADF;



	*prev = vma;

	start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;

	if (end > vma->vm_end)

		end = vma->vm_end;
@@ -100,8 +118,10 @@ static long madvise_willneed(struct vm_area_struct * vma, 
 * dirty pages is already available as msync(MS_INVALIDATE).

 */

static long madvise_dontneed(struct vm_area_struct * vma,

			     struct vm_area_struct ** prev,

			     unsigned long start, unsigned long end)

{

	*prev = vma;

	if ((vma->vm_flags & VM_LOCKED) || is_vm_hugetlb_page(vma))

		return -EINVAL;
@@ -116,8 +136,8 @@ static long madvise_dontneed(struct vm_area_struct * vma, 
	return 0;

}



static long madvise_vma(struct vm_area_struct * vma, unsigned long start,

			unsigned long end, int behavior)

static long madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,

			unsigned long start, unsigned long end, int behavior)

{

	long error = -EBADF;
@@ -125,15 +145,15 @@ static long madvise_vma(struct vm_area_struct * vma, unsigned long start, 
	case MADV_NORMAL:

	case MADV_SEQUENTIAL:

	case MADV_RANDOM:

		error = madvise_behavior(vma, start, end, behavior);

		error = madvise_behavior(vma, prev, start, end, behavior);

		break;



	case MADV_WILLNEED:

		error = madvise_willneed(vma, start, end);

		error = madvise_willneed(vma, prev, start, end);

		break;



	case MADV_DONTNEED:

		error = madvise_dontneed(vma, start, end);

		error = madvise_dontneed(vma, prev, start, end);

		break;



	default:
@@ -180,8 +200,8 @@ static long madvise_vma(struct vm_area_struct * vma, unsigned long start, 
 */

asmlinkage long sys_madvise(unsigned long start, size_t len_in, int behavior)

{

	unsigned long end;

	struct vm_area_struct * vma;

	unsigned long end, tmp;

	struct vm_area_struct * vma, *prev;

	int unmapped_error = 0;

	int error = -EINVAL;

	size_t len;
@@ -207,40 +227,42 @@ asmlinkage long sys_madvise(unsigned long start, size_t len_in, int behavior) 
	/*

	 * If the interval [start,end) covers some unmapped address

	 * ranges, just ignore them, but return -ENOMEM at the end.

	 * - different from the way of handling in mlock etc.

	 */

	vma = find_vma(current->mm, start);

	vma = find_vma_prev(current->mm, start, &prev);

	if (!vma && prev)

		vma = prev->vm_next;

	for (;;) {

		/* Still start < end. */

		error = -ENOMEM;

		if (!vma)

			goto out;



		/* Here start < vma->vm_end. */

		/* Here start < (end|vma->vm_end). */

		if (start < vma->vm_start) {

			unmapped_error = -ENOMEM;

			start = vma->vm_start;

			if (start >= end)

				goto out;

		}



		/* Here vma->vm_start <= start < vma->vm_end. */

		if (end <= vma->vm_end) {

			if (start < end) {

				error = madvise_vma(vma, start, end,

							behavior);

		/* Here vma->vm_start <= start < (end|vma->vm_end) */

		tmp = vma->vm_end;

		if (end < tmp)

			tmp = end;



		/* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */

		error = madvise_vma(vma, &prev, start, tmp, behavior);

		if (error)

			goto out;

			}

		start = tmp;

		if (start < prev->vm_end)

			start = prev->vm_end;

		error = unmapped_error;

		if (start >= end)

			goto out;

		vma = prev->vm_next;

	}



		/* Here vma->vm_start <= start < vma->vm_end < end. */

		error = madvise_vma(vma, start, vma->vm_end, behavior);

		if (error)

			goto out;

		start = vma->vm_end;

		vma = vma->vm_next;

	}



out:

	up_write(&current->mm->mmap_sem);

	return error;