[Devel] [PATCH RHEL7 COMMIT] Revert "ms/memcg/proc: add kpagecgroup file"

[Konstantin Khorenko]

The commit is pushed to "branch-rh7-3.10.0-229.7.2.vz7.9.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-229.7.2.vz7.9.6
------>
commit 5f0365be2b5be78b0f5156bef2f989175627bda8
Author: Vladimir Davydov <vdavydov at virtuozzo.com>
Date:   Thu Nov 5 17:36:21 2015 +0400

    Revert "ms/memcg/proc: add kpagecgroup file"
    
    https://jira.sw.ru/browse/PSBM-32460
    
    Mainstream has been updated since we pulled this feature. Need to pull
    it again.
    
    This reverts commit e130f803d53a5ae484726304c13406b387e327cb.
    
    Signed-off-by: Vladimir Davydov <vdavydov at virtuozzo.com>
---
 Documentation/vm/pagemap.txt |  6 +----
 fs/proc/Kconfig              |  5 ++---
 fs/proc/page.c               | 53 --------------------------------------------
 3 files changed, 3 insertions(+), 61 deletions(-)

diff --git a/Documentation/vm/pagemap.txt b/Documentation/vm/pagemap.txt
index e37cff9..fd7c3cf 100644
--- a/Documentation/vm/pagemap.txt
+++ b/Documentation/vm/pagemap.txt
@@ -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 four components to pagemap:
+There are three 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
@@ -63,10 +63,6 @@ There are four components to pagemap:
     21. KSM
     22. THP
 
- * /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
diff --git a/fs/proc/Kconfig b/fs/proc/Kconfig
index e8ed22d..15af622 100644
--- a/fs/proc/Kconfig
+++ b/fs/proc/Kconfig
@@ -65,6 +65,5 @@ config PROC_PAGE_MONITOR
  	help
 	  Various /proc files exist to monitor process memory utilization:
 	  /proc/pid/smaps, /proc/pid/clear_refs, /proc/pid/pagemap,
-	  /proc/kpagecount, /proc/kpageflags, and /proc/kpagecgroup.
-	  Disabling these interfaces will reduce the size of the kernel
-	  by approximately 4kb.
+	  /proc/kpagecount, and /proc/kpageflags. Disabling these
+          interfaces will reduce the size of the kernel by approximately 4kb.
diff --git a/fs/proc/page.c b/fs/proc/page.c
index f198973..54e111e 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -8,7 +8,6 @@
 #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"
@@ -213,62 +212,10 @@ 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;
 }
 module_init(proc_page_init);