There is a race window between vmap_area free and show vmap_area information.
A B
remove_vm_area
spin_lock(&vmap_area_lock);
va->flags &= ~VM_VM_AREA;
spin_unlock(&vmap_area_lock);
spin_lock(&vmap_area_lock);
if (va->flags & (VM_LAZY_FREE |
VM_LAZY_FREEZING))
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;
}
free_unmap_vmap_area(va);
flush_cache_vunmap
free_unmap_vmap_area_noflush
unmap_vmap_area
free_vmap_area_noflush
va->flags |= VM_LAZY_FREE
The assumption is introduced by commit: d4033afd(mm, vmalloc: iterate
vmap_area_list,
instead of vmlist, in vmallocinfo()). This patch fix it by drop the assumption
and
keep not dump vm_map_ram allocation information as the logic before that commit.
Signed-off-by: Wanpeng Li <[email protected]>
---
mm/vmalloc.c | 7 -------
1 file changed, 7 deletions(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 5368b17..62b7932 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2586,13 +2586,6 @@ static int s_show(struct seq_file *m, void *p)
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",
--
1.8.1.2
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