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Message-Id: <11.430487409@selenic.com>
Date: Fri, 26 Oct 2007 11:36:36 -0500
From: Matt Mackall <mpm@...enic.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org
Cc: Dave Hansen <haveblue@...ibm.com>,
Rusty Russell <rusty@...tcorp.com.au>,
Jeremy Fitzhardinge <jeremy@...p.org>,
David Rientjes <rientjes@...gle.com>,
Fengguang Wu <wfg@...l.ustc.edu.cn>
Subject: [PATCH 10/12] maps4: add /proc/kpagecount interface
From: Matt Mackall <mpm@...enic.com>
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.
[bunk@...sta.de: make struct proc_kpagemap static]
Signed-off-by: Matt Mackall <mpm@...enic.com>
Cc: Jeremy Fitzhardinge <jeremy@...p.org>
Cc: David Rientjes <rientjes@...gle.com>
Signed-off-by: Adrian Bunk <bunk@...sta.de>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---
Index: l/fs/proc/proc_misc.c
===================================================================
--- l.orig/fs/proc/proc_misc.c 2007-10-22 16:24:34.000000000 -0500
+++ l/fs/proc/proc_misc.c 2007-10-22 17:53:48.000000000 -0500
@@ -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>
@@ -656,6 +657,57 @@ static const struct file_operations proc
};
#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;
+
+ if (!access_ok(VERIFY_WRITE, buf, count))
+ return -EFAULT;
+
+ 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)
@@ -735,6 +787,7 @@ 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)
-
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