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Commit 161f47bf authored by Matt Mackall's avatar Matt Mackall Committed by Linus Torvalds
Browse files

maps4: add /proc/kpagecount interface 



This makes physical page map counts available to userspace. Together
with /proc/pid/pagemap and /proc/pid/clear_refs, this can be used to
monitor memory usage on a per-page basis.

[akpm@linux-foundation.org: remove unneeded access_ok()]
[bunk@stusta.de: make struct proc_kpagemap static]
Signed-off-by: default avatarMatt Mackall <mpm@selenic.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: default avatarAdrian Bunk <bunk@stusta.de>
Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 85863e47

fs/proc/proc_misc.c

+50 −0
Original line number Diff line number Diff line
@@ -46,6 +46,7 @@ 
#include <linux/vmalloc.h>

#include <linux/crash_dump.h>

#include <linux/pid_namespace.h>

#include <linux/bootmem.h>

#include <asm/uaccess.h>

#include <asm/pgtable.h>

#include <asm/io.h>
@@ -675,6 +676,54 @@ static const struct file_operations proc_sysrq_trigger_operations = { 
};

#endif



#define KPMSIZE sizeof(u64)

#define KPMMASK (KPMSIZE - 1)

/* /proc/kpagecount - an array exposing page counts

 *

 * Each entry is a u64 representing the corresponding

 * physical page count.

 */

static ssize_t kpagecount_read(struct file *file, char __user *buf,

			     size_t count, loff_t *ppos)

{

	u64 __user *out = (u64 __user *)buf;

	struct page *ppage;

	unsigned long src = *ppos;

	unsigned long pfn;

	ssize_t ret = 0;

	u64 pcount;



	pfn = src / KPMSIZE;

	count = min_t(size_t, count, (max_pfn * KPMSIZE) - src);

	if (src & KPMMASK || count & KPMMASK)

		return -EIO;



	while (count > 0) {

		ppage = pfn_to_page(pfn++);

		if (!ppage)

			pcount = 0;

		else

			pcount = atomic_read(&ppage->_count);



		if (put_user(pcount, out++)) {

			ret = -EFAULT;

			break;

		}



		count -= KPMSIZE;

	}



	*ppos += (char __user *)out - buf;

	if (!ret)

		ret = (char __user *)out - buf;

	return ret;

}



static struct file_operations proc_kpagecount_operations = {

	.llseek = mem_lseek,

	.read = kpagecount_read,

};



struct proc_dir_entry *proc_root_kcore;



void create_seq_entry(char *name, mode_t mode, const struct file_operations *f)
@@ -755,6 +804,7 @@ void __init proc_misc_init(void) 
				(size_t)high_memory - PAGE_OFFSET + PAGE_SIZE;

	}

#endif

	create_seq_entry("kpagecount", S_IRUSR, &proc_kpagecount_operations);

#ifdef CONFIG_PROC_VMCORE

	proc_vmcore = create_proc_entry("vmcore", S_IRUSR, NULL);

	if (proc_vmcore)