Commit d4033afd authored by Joonsoo Kim's avatar Joonsoo Kim Committed by Linus Torvalds

mm, vmalloc: iterate vmap_area_list, instead of vmlist, in vmallocinfo()

This patch is a preparatory step for removing vmlist entirely.  For
above purpose, we change iterating a vmap_list codes to iterating a
vmap_area_list.  It is somewhat trivial change, but just one thing
should be noticed.

Using vmap_area_list in vmallocinfo() introduce ordering problem in SMP
system.  In s_show(), we retrieve some values from vm_struct.
vm_struct's values is not fully setup when va->vm is assigned.  Full
setup is notified by removing VM_UNLIST flag without holding a lock.
When we see that VM_UNLIST is removed, it is not ensured that vm_struct
has proper values in view of other CPUs.  So we need smp_[rw]mb for
ensuring that proper values is assigned when we see that VM_UNLIST is
removed.

Therefore, this patch not only change a iteration list, but also add a
appropriate smp_[rw]mb to right places.
Signed-off-by: default avatarJoonsoo Kim <js1304@gmail.com>
Signed-off-by: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Dave Anderson <anderson@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent f98782dd
......@@ -1304,7 +1304,14 @@ static void insert_vmalloc_vmlist(struct vm_struct *vm)
{
struct vm_struct *tmp, **p;
/*
* Before removing VM_UNLIST,
* we should make sure that vm has proper values.
* Pair with smp_rmb() in show_numa_info().
*/
smp_wmb();
vm->flags &= ~VM_UNLIST;
write_lock(&vmlist_lock);
for (p = &vmlist; (tmp = *p) != NULL; p = &tmp->next) {
if (tmp->addr >= vm->addr)
......@@ -2542,19 +2549,19 @@ void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms)
#ifdef CONFIG_PROC_FS
static void *s_start(struct seq_file *m, loff_t *pos)
__acquires(&vmlist_lock)
__acquires(&vmap_area_lock)
{
loff_t n = *pos;
struct vm_struct *v;
struct vmap_area *va;
read_lock(&vmlist_lock);
v = vmlist;
while (n > 0 && v) {
spin_lock(&vmap_area_lock);
va = list_entry((&vmap_area_list)->next, typeof(*va), list);
while (n > 0 && &va->list != &vmap_area_list) {
n--;
v = v->next;
va = list_entry(va->list.next, typeof(*va), list);
}
if (!n)
return v;
if (!n && &va->list != &vmap_area_list)
return va;
return NULL;
......@@ -2562,16 +2569,20 @@ static void *s_start(struct seq_file *m, loff_t *pos)
static void *s_next(struct seq_file *m, void *p, loff_t *pos)
{
struct vm_struct *v = p;
struct vmap_area *va = p, *next;
++*pos;
return v->next;
next = list_entry(va->list.next, typeof(*va), list);
if (&next->list != &vmap_area_list)
return next;
return NULL;
}
static void s_stop(struct seq_file *m, void *p)
__releases(&vmlist_lock)
__releases(&vmap_area_lock)
{
read_unlock(&vmlist_lock);
spin_unlock(&vmap_area_lock);
}
static void show_numa_info(struct seq_file *m, struct vm_struct *v)
......@@ -2582,6 +2593,11 @@ static void show_numa_info(struct seq_file *m, struct vm_struct *v)
if (!counters)
return;
/* Pair with smp_wmb() in insert_vmalloc_vmlist() */
smp_rmb();
if (v->flags & VM_UNLIST)
return;
memset(counters, 0, nr_node_ids * sizeof(unsigned int));
for (nr = 0; nr < v->nr_pages; nr++)
......@@ -2595,7 +2611,20 @@ static void show_numa_info(struct seq_file *m, struct vm_struct *v)
static int s_show(struct seq_file *m, void *p)
{
struct vm_struct *v = p;
struct vmap_area *va = p;
struct vm_struct *v;
if (va->flags & (VM_LAZY_FREE | VM_LAZY_FREEING))
return 0;
if (!(va->flags & VM_VM_AREA)) {
seq_printf(m, "0x%pK-0x%pK %7ld vm_map_ram\n",
(void *)va->va_start, (void *)va->va_end,
va->va_end - va->va_start);
return 0;
}
v = va->vm;
seq_printf(m, "0x%pK-0x%pK %7ld",
v->addr, v->addr + v->size, v->size);
......
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