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: Vladimir Davydov <vdavydov@parallels.com> Reviewed-by: Andres 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: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -5,7 +5,7 @@ pagemap is a new (as of 2.6.25) set of interfaces in the kernel that allow
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userspace programs to examine the page tables and related information by
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reading files in /proc.
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There are three components to pagemap:
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There are four components to pagemap:
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* /proc/pid/pagemap. This file lets a userspace process find out which
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physical frame each virtual page is mapped to. It contains one 64-bit
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@ -71,6 +71,10 @@ There are three components to pagemap:
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23. BALLOON
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24. ZERO_PAGE
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* /proc/kpagecgroup. This file contains a 64-bit inode number of the
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memory cgroup each page is charged to, indexed by PFN. Only available when
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CONFIG_MEMCG is set.
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Short descriptions to the page flags:
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0. LOCKED
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@ -9,6 +9,7 @@
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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#include <linux/hugetlb.h>
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#include <linux/memcontrol.h>
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#include <linux/kernel-page-flags.h>
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#include <asm/uaccess.h>
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#include "internal.h"
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@ -225,10 +226,62 @@ static const struct file_operations proc_kpageflags_operations = {
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.read = kpageflags_read,
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};
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#ifdef CONFIG_MEMCG
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static ssize_t kpagecgroup_read(struct file *file, char __user *buf,
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size_t count, loff_t *ppos)
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{
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u64 __user *out = (u64 __user *)buf;
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struct page *ppage;
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unsigned long src = *ppos;
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unsigned long pfn;
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ssize_t ret = 0;
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u64 ino;
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pfn = src / KPMSIZE;
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count = min_t(unsigned long, count, (max_pfn * KPMSIZE) - src);
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if (src & KPMMASK || count & KPMMASK)
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return -EINVAL;
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while (count > 0) {
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if (pfn_valid(pfn))
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ppage = pfn_to_page(pfn);
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else
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ppage = NULL;
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if (ppage)
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ino = page_cgroup_ino(ppage);
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else
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ino = 0;
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if (put_user(ino, out)) {
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ret = -EFAULT;
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break;
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}
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pfn++;
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out++;
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count -= KPMSIZE;
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}
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*ppos += (char __user *)out - buf;
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if (!ret)
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ret = (char __user *)out - buf;
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return ret;
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}
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static const struct file_operations proc_kpagecgroup_operations = {
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.llseek = mem_lseek,
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.read = kpagecgroup_read,
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};
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#endif /* CONFIG_MEMCG */
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static int __init proc_page_init(void)
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{
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proc_create("kpagecount", S_IRUSR, NULL, &proc_kpagecount_operations);
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proc_create("kpageflags", S_IRUSR, NULL, &proc_kpageflags_operations);
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#ifdef CONFIG_MEMCG
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proc_create("kpagecgroup", S_IRUSR, NULL, &proc_kpagecgroup_operations);
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#endif
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return 0;
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}
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fs_initcall(proc_page_init);
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