Commit a10aa579 authored by Christoph Lameter's avatar Christoph Lameter Committed by Linus Torvalds

vmalloc: show vmalloced areas via /proc/vmallocinfo

Implement a new proc file that allows the display of the currently allocated
vmalloc memory.

It allows to see the users of vmalloc.  That is important if vmalloc space is
scarce (i386 for example).

And it's going to be important for the compound page fallback to vmalloc.
Many of the current users can be switched to use compound pages with fallback.
 This means that the number of users of vmalloc is reduced and page tables no
longer necessary to access the memory.  /proc/vmallocinfo allows to review how
that reduction occurs.

If memory becomes fragmented and larger order allocations are no longer
possible then /proc/vmallocinfo allows to see which compound page allocations
fell back to virtual compound pages.  That is important for new users of
virtual compound pages.  Such as order 1 stack allocation etc that may
fallback to virtual compound pages in the future.

/proc/vmallocinfo permissions are made readable-only-by-root to avoid possible
information leakage.

[ coding-style fixes]
[ CONFIG_MMU=n build fix]
Signed-off-by: default avatarChristoph Lameter <>
Reviewed-by: default avatarKOSAKI Motohiro <>
Cc: Hugh Dickins <>
Cc: Nick Piggin <>
Cc: Arjan van de Ven <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent b4544568
......@@ -456,6 +456,20 @@ static const struct file_operations proc_slabstats_operations = {
static int vmalloc_open(struct inode *inode, struct file *file)
return seq_open(file, &vmalloc_op);
static const struct file_operations proc_vmalloc_operations = {
.open = vmalloc_open,
.read = seq_read,
.llseek = seq_lseek,
.release = seq_release,
static int show_stat(struct seq_file *p, void *v)
int i;
......@@ -868,6 +882,9 @@ void __init proc_misc_init(void)
create_seq_entry("slab_allocators", 0 ,&proc_slabstats_operations);
proc_create("vmallocinfo", S_IRUSR, NULL, &proc_vmalloc_operations);
create_seq_entry("buddyinfo",S_IRUGO, &fragmentation_file_operations);
create_seq_entry("pagetypeinfo", S_IRUGO, &pagetypeinfo_file_ops);
......@@ -87,4 +87,6 @@ extern void free_vm_area(struct vm_struct *area);
extern rwlock_t vmlist_lock;
extern struct vm_struct *vmlist;
extern const struct seq_operations vmalloc_op;
#endif /* _LINUX_VMALLOC_H */
......@@ -14,7 +14,7 @@
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/interrupt.h>
#include <linux/seq_file.h>
#include <linux/vmalloc.h>
#include <asm/uaccess.h>
......@@ -873,3 +873,77 @@ void free_vm_area(struct vm_struct *area)
static void *s_start(struct seq_file *m, loff_t *pos)
loff_t n = *pos;
struct vm_struct *v;
v = vmlist;
while (n > 0 && v) {
v = v->next;
if (!n)
return v;
return NULL;
static void *s_next(struct seq_file *m, void *p, loff_t *pos)
struct vm_struct *v = p;
return v->next;
static void s_stop(struct seq_file *m, void *p)
static int s_show(struct seq_file *m, void *p)
struct vm_struct *v = p;
seq_printf(m, "0x%p-0x%p %7ld",
v->addr, v->addr + v->size, v->size);
if (v->nr_pages)
seq_printf(m, " pages=%d", v->nr_pages);
if (v->phys_addr)
seq_printf(m, " phys=%lx", v->phys_addr);
if (v->flags & VM_IOREMAP)
seq_printf(m, " ioremap");
if (v->flags & VM_ALLOC)
seq_printf(m, " vmalloc");
if (v->flags & VM_MAP)
seq_printf(m, " vmap");
if (v->flags & VM_USERMAP)
seq_printf(m, " user");
if (v->flags & VM_VPAGES)
seq_printf(m, " vpages");
seq_putc(m, '\n');
return 0;
const struct seq_operations vmalloc_op = {
.start = s_start,
.next = s_next,
.stop = s_stop,
.show = s_show,
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment