The patch titled
Subject: mm, vmalloc: iterate vmap_area_list, instead of vmlist, in vmallocinfo()
has been added to the -mm tree. Its filename is
mm-vmalloc-iterate-vmap_area_list-instead-of-vmlist-in-vmallocinfo.patch
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------------------------------------------------------
From: Joonsoo Kim <js1304@xxxxxxxxx>
Subject: 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: Joonsoo Kim <js1304@xxxxxxxxx>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Atsushi Kumagai <kumagai-atsushi@xxxxxxxxxxxxxxxxx>
Cc: Chris Metcalf <cmetcalf@xxxxxxxxxx>
Cc: Dave Anderson <anderson@xxxxxxxxxx>
Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Guan Xuetao <gxt@xxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Vivek Goyal <vgoyal@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmalloc.c | 55 +++++++++++++++++++++++++++++++++++++------------
1 file changed, 42 insertions(+), 13 deletions(-)
diff -puN mm/vmalloc.c~mm-vmalloc-iterate-vmap_area_list-instead-of-vmlist-in-vmallocinfo mm/vmalloc.c
--- a/mm/vmalloc.c~mm-vmalloc-iterate-vmap_area_list-instead-of-vmlist-in-vmallocinfo
+++ a/mm/vmalloc.c
@@ -1304,7 +1304,14 @@ static void insert_vmalloc_vmlist(struct
{
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
#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,
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_fi
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_fi
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);
_
Patches currently in -mm which might be from js1304@xxxxxxxxx are
linux-next.patch
mm-vmalloc-change-iterating-a-vmlist-to-find_vm_area.patch
mm-vmalloc-move-get_vmalloc_info-to-vmallocc.patch
mm-vmalloc-protect-va-vm-by-vmap_area_lock.patch
mm-vmalloc-iterate-vmap_area_list-instead-of-vmlist-in-vread-vwrite.patch
mm-vmalloc-iterate-vmap_area_list-in-get_vmalloc_info.patch
mm-vmalloc-iterate-vmap_area_list-instead-of-vmlist-in-vmallocinfo.patch
mm-vmalloc-export-vmap_area_list-instead-of-vmlist.patch
mm-vmalloc-remove-list-management-of-vmlist-after-initializing-vmalloc.patch
--
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