Release 4.11 mm/mincore.c

/*
 *      linux/mm/mincore.c
 *
 * Copyright (C) 1994-2006  Linus Torvalds
 */

/*
 * The mincore() system call.
 */
#include <linux/pagemap.h>
#include <linux/gfp.h>
#include <linux/mm.h>
#include <linux/mman.h>
#include <linux/syscalls.h>
#include <linux/swap.h>
#include <linux/swapops.h>
#include <linux/shmem_fs.h>
#include <linux/hugetlb.h>

#include <linux/uaccess.h>
#include <asm/pgtable.h>



static int mincore_hugetlb(pte_t *pte, unsigned long hmask, unsigned long addr,
			unsigned long end, struct mm_walk *walk)
{
#ifdef CONFIG_HUGETLB_PAGE
	unsigned char present;
	unsigned char *vec = walk->private;

	/*
         * Hugepages under user process are always in RAM and never
         * swapped out, but theoretically it needs to be checked.
         */
	present = pte && !huge_pte_none(huge_ptep_get(pte));
	for (; addr != end; vec++, addr += PAGE_SIZE)
		*vec = present;
	walk->private = vec;
#else
	BUG();
#endif
	return 0;
}

Contributors
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Naoya Horiguchi
61
66.30%
2
28.57%
Johannes Weiner
19
20.65%
3
42.86%
Linus Torvalds
12
13.04%
2
28.57%
Total
92
100.00%
7
100.00%

/*
 * Later we can get more picky about what "in core" means precisely.
 * For now, simply check to see if the page is in the page cache,
 * and is up to date; i.e. that no page-in operation would be required
 * at this time if an application were to map and access this page.
 */


static unsigned char mincore_page(struct address_space *mapping, pgoff_t pgoff)
{
	unsigned char present = 0;
	struct page *page;

	/*
         * When tmpfs swaps out a page from a file, any process mapping that
         * file will not get a swp_entry_t in its pte, but rather it is like
         * any other file mapping (ie. marked !present and faulted in with
         * tmpfs's .fault). So swapped out tmpfs mappings are tested here.
         */
#ifdef CONFIG_SWAP
	if (shmem_mapping(mapping)) {
		page = find_get_entry(mapping, pgoff);
		/*
                 * shmem/tmpfs may return swap: account for swapcache
                 * page too.
                 */
		if (radix_tree_exceptional_entry(page)) {
			swp_entry_t swp = radix_to_swp_entry(page);
			page = find_get_page(swap_address_space(swp),
					     swp_offset(swp));
		}
	} else
		page = find_get_page(mapping, pgoff);
#else
	page = find_get_page(mapping, pgoff);
#endif
	if (page) {
		present = PageUptodate(page);
		put_page(page);
	}

	return present;
}

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Johannes Weiner
83
66.40%
3
27.27%
Hugh Dickins
26
20.80%
1
9.09%
Nicholas Piggin
7
5.60%
2
18.18%
Shaohua Li
3
2.40%
1
9.09%
Huang Ying
3
2.40%
1
9.09%
Linus Torvalds
2
1.60%
2
18.18%
Kirill A. Shutemov
1
0.80%
1
9.09%
Total
125
100.00%
11
100.00%



static int __mincore_unmapped_range(unsigned long addr, unsigned long end,
				struct vm_area_struct *vma, unsigned char *vec)
{
	unsigned long nr = (end - addr) >> PAGE_SHIFT;
	int i;

	if (vma->vm_file) {
		pgoff_t pgoff;

		pgoff = linear_page_index(vma, addr);
		for (i = 0; i < nr; i++, pgoff++)
			vec[i] = mincore_page(vma->vm_file->f_mapping, pgoff);
	} else {
		for (i = 0; i < nr; i++)
			vec[i] = 0;
	}
	return nr;
}

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Johannes Weiner
95
81.20%
2
50.00%
Nicholas Piggin
12
10.26%
1
25.00%
Naoya Horiguchi
10
8.55%
1
25.00%
Total
117
100.00%
4
100.00%



static int mincore_unmapped_range(unsigned long addr, unsigned long end,
				   struct mm_walk *walk)
{
	walk->private += __mincore_unmapped_range(addr, end,
						  walk->vma, walk->private);
	return 0;
}

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12.20%
1
50.00%
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41
100.00%
2
100.00%



static int mincore_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
			struct mm_walk *walk)
{
	spinlock_t *ptl;
	struct vm_area_struct *vma = walk->vma;
	pte_t *ptep;
	unsigned char *vec = walk->private;
	int nr = (end - addr) >> PAGE_SHIFT;

	ptl = pmd_trans_huge_lock(pmd, vma);
	if (ptl) {
		memset(vec, 1, nr);
		spin_unlock(ptl);
		goto out;
	}

	if (pmd_trans_unstable(pmd)) {
		__mincore_unmapped_range(addr, end, vma, vec);
		goto out;
	}

	ptep = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
	for (; addr != end; ptep++, addr += PAGE_SIZE) {
		pte_t pte = *ptep;

		if (pte_none(pte))
			__mincore_unmapped_range(addr, addr + PAGE_SIZE,
						 vma, vec);
		else if (pte_present(pte))
			*vec = 1;
		else { /* pte is a swap entry */
			swp_entry_t entry = pte_to_swp_entry(pte);

			if (non_swap_entry(entry)) {
				/*
                                 * migration or hwpoison entries are always
                                 * uptodate
                                 */
				*vec = 1;
			} else {
#ifdef CONFIG_SWAP
				*vec = mincore_page(swap_address_space(entry),
						    swp_offset(entry));
#else
				WARN_ON(1);
				*vec = 1;
#endif
			}
		}
		vec++;
	}
	pte_unmap_unlock(ptep - 1, ptl);
out:
	walk->private += nr;
	cond_resched();
	return 0;
}

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117
42.55%
1
7.69%
Nicholas Piggin
91
33.09%
2
15.38%
Johannes Weiner
49
17.82%
4
30.77%
Kirill A. Shutemov
7
2.55%
2
15.38%
Shaohua Li
4
1.45%
1
7.69%
Huang Ying
3
1.09%
1
7.69%
Weijie Yang
2
0.73%
1
7.69%
Linus Torvalds
2
0.73%
1
7.69%
Total
275
100.00%
13
100.00%

/*
 * Do a chunk of "sys_mincore()". We've already checked
 * all the arguments, we hold the mmap semaphore: we should
 * just return the amount of info we're asked for.
 */


static long do_mincore(unsigned long addr, unsigned long pages, unsigned char *vec)
{
	struct vm_area_struct *vma;
	unsigned long end;
	int err;
	struct mm_walk mincore_walk = {
		.pmd_entry = mincore_pte_range,
		.pte_hole = mincore_unmapped_range,
		.hugetlb_entry = mincore_hugetlb,
		.private = vec,
        };

	vma = find_vma(current->mm, addr);
	if (!vma || addr < vma->vm_start)
		return -ENOMEM;
	mincore_walk.mm = vma->vm_mm;
	end = min(vma->vm_end, addr + (pages << PAGE_SHIFT));
	err = walk_page_range(addr, end, &mincore_walk);
	if (err < 0)
		return err;
	return (end - addr) >> PAGE_SHIFT;
}

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Johannes Weiner
77
55.80%
3
42.86%
Naoya Horiguchi
51
36.96%
1
14.29%
Nicholas Piggin
7
5.07%
2
28.57%
Linus Torvalds
3
2.17%
1
14.29%
Total
138
100.00%
7
100.00%

/*
 * The mincore(2) system call.
 *
 * mincore() returns the memory residency status of the pages in the
 * current process's address space specified by [addr, addr + len).
 * The status is returned in a vector of bytes.  The least significant
 * bit of each byte is 1 if the referenced page is in memory, otherwise
 * it is zero.
 *
 * Because the status of a page can change after mincore() checks it
 * but before it returns to the application, the returned vector may
 * contain stale information.  Only locked pages are guaranteed to
 * remain in memory.
 *
 * return values:
 *  zero    - success
 *  -EFAULT - vec points to an illegal address
 *  -EINVAL - addr is not a multiple of PAGE_SIZE
 *  -ENOMEM - Addresses in the range [addr, addr + len] are
 *              invalid for the address space of this process, or
 *              specify one or more pages which are not currently
 *              mapped
 *  -EAGAIN - A kernel resource was temporarily unavailable.
 */

SYSCALL_DEFINE3(mincore, unsigned long, start, size_t, len,
		unsigned char __user *, vec)
{
	long retval;
	unsigned long pages;
	unsigned char *tmp;

	/* Check the start address: needs to be page-aligned.. */
	if (start & ~PAGE_MASK)
		return -EINVAL;

	/* ..and we need to be passed a valid user-space range */
	if (!access_ok(VERIFY_READ, (void __user *) start, len))
		return -ENOMEM;

	/* This also avoids any overflows on PAGE_ALIGN */
	pages = len >> PAGE_SHIFT;
	pages += (offset_in_page(len)) != 0;

	if (!access_ok(VERIFY_WRITE, vec, pages))
		return -EFAULT;

	tmp = (void *) __get_free_page(GFP_USER);
	if (!tmp)
		return -EAGAIN;

	retval = 0;
	while (pages) {
		/*
                 * Do at most PAGE_SIZE entries per iteration, due to
                 * the temporary buffer size.
                 */
		down_read(&current->mm->mmap_sem);
		retval = do_mincore(start, min(pages, PAGE_SIZE), tmp);
		up_read(&current->mm->mmap_sem);

		if (retval <= 0)
			break;
		if (copy_to_user(vec, tmp, retval)) {
			retval = -EFAULT;
			break;
		}
		pages -= retval;
		vec += retval;
		start += retval << PAGE_SHIFT;
		retval = 0;
	}
	free_page((unsigned long) tmp);
	return retval;
}
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31.71%
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16.13%
Naoya Horiguchi
278
26.55%
2
6.45%
Linus Torvalds
210
20.06%
4
12.90%
Nicholas Piggin
123
11.75%
4
12.90%
Hugh Dickins
29
2.77%
2
6.45%
David Howells
16
1.53%
1
3.23%
Heiko Carstens
16
1.53%
1
3.23%
Kirill A. Shutemov
11
1.05%
4
12.90%
Gordon Jin
8
0.76%
1
3.23%
Shaohua Li
7
0.67%
1
3.23%
Huang Ying
6
0.57%
1
3.23%
Arnd Bergmann
3
0.29%
1
3.23%
Alexander Kuleshov
3
0.29%
1
3.23%
Weijie Yang
2
0.19%
1
3.23%
Tejun Heo
2
0.19%
1
3.23%
Oleg Nesterov
1
0.10%
1
3.23%
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1047
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31
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Directory: mm

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