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

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

mm/vmalloc.c

+42 −13
Original line number Diff line number Diff line
@@ -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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