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Commit 80ae2fdc authored by Vladimir Davydov's avatar Vladimir Davydov Committed by Linus Torvalds
Browse files

proc: add kpagecgroup file 



/proc/kpagecgroup contains a 64-bit inode number of the memory cgroup each
page is charged to, indexed by PFN.  Having this information is useful for
estimating a cgroup working set size.

The file is present if CONFIG_PROC_PAGE_MONITOR && CONFIG_MEMCG.

Signed-off-by: default avatarVladimir Davydov <vdavydov@parallels.com>
Reviewed-by: default avatarAndres Lagar-Cavilla <andreslc@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Raghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Greg Thelen <gthelen@google.com>
Cc: Michel Lespinasse <walken@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent e993d905

Documentation/vm/pagemap.txt

+5 −1
Original line number Diff line number Diff line
@@ -5,7 +5,7 @@ pagemap is a new (as of 2.6.25) set of interfaces in the kernel that allow 
userspace programs to examine the page tables and related information by

reading files in /proc.



There are three components to pagemap:

There are four components to pagemap:



 * /proc/pid/pagemap.  This file lets a userspace process find out which

   physical frame each virtual page is mapped to.  It contains one 64-bit
@@ -71,6 +71,10 @@ There are three components to pagemap: 
    23. BALLOON

    24. ZERO_PAGE



 * /proc/kpagecgroup.  This file contains a 64-bit inode number of the

   memory cgroup each page is charged to, indexed by PFN. Only available when

   CONFIG_MEMCG is set.



Short descriptions to the page flags:



 0. LOCKED

fs/proc/page.c

+53 −0
Original line number Diff line number Diff line
@@ -9,6 +9,7 @@ 
#include <linux/proc_fs.h>

#include <linux/seq_file.h>

#include <linux/hugetlb.h>

#include <linux/memcontrol.h>

#include <linux/kernel-page-flags.h>

#include <asm/uaccess.h>

#include "internal.h"
@@ -225,10 +226,62 @@ static const struct file_operations proc_kpageflags_operations = { 
	.read = kpageflags_read,

};



#ifdef CONFIG_MEMCG

static ssize_t kpagecgroup_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 ino;



	pfn = src / KPMSIZE;

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

	if (src & KPMMASK || count & KPMMASK)

		return -EINVAL;



	while (count > 0) {

		if (pfn_valid(pfn))

			ppage = pfn_to_page(pfn);

		else

			ppage = NULL;



		if (ppage)

			ino = page_cgroup_ino(ppage);

		else

			ino = 0;



		if (put_user(ino, out)) {

			ret = -EFAULT;

			break;

		}



		pfn++;

		out++;

		count -= KPMSIZE;

	}



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

	if (!ret)

		ret = (char __user *)out - buf;

	return ret;

}



static const struct file_operations proc_kpagecgroup_operations = {

	.llseek = mem_lseek,

	.read = kpagecgroup_read,

};

#endif /* CONFIG_MEMCG */



static int __init proc_page_init(void)

{

	proc_create("kpagecount", S_IRUSR, NULL, &proc_kpagecount_operations);

	proc_create("kpageflags", S_IRUSR, NULL, &proc_kpageflags_operations);

#ifdef CONFIG_MEMCG

	proc_create("kpagecgroup", S_IRUSR, NULL, &proc_kpagecgroup_operations);

#endif

	return 0;

}

fs_initcall(proc_page_init);