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maps4: add /proc/kpagecount interface

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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: Matt Mackall <mpm@selenic.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Matt Mackall 2008-02-04 22:29:05 -08:00 committed by Linus Torvalds
parent 85863e475e
commit 161f47bf41
1 changed files with 50 additions and 0 deletions
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50
fs/proc/proc_misc.c
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@ -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)