From 0f06ed1b0aa5f56291e23dddf619c4f3a3f3d1e4 Mon Sep 17 00:00:00 2001 From: Joonsoo Kim Date: Wed, 20 Mar 2013 15:07:25 +1100 Subject: [PATCH] mm, vmalloc: protect va->vm by vmap_area_lock Inserting and removing an entry to vmlist is linear time complexity, so it is inefficient. Following patches will try to remove vmlist entirely. This patch is preparing step for it. For removing vmlist, iterating vmlist codes should be changed to iterating a vmap_area_list. Before implementing that, we should make sure that when we iterate a vmap_area_list, accessing to va->vm doesn't cause a race condition. This patch ensure that when iterating a vmap_area_list, there is no race condition for accessing to vm_struct. Signed-off-by: Joonsoo Kim Signed-off-by: Joonsoo Kim Cc: Thomas Gleixner Cc: "H. Peter Anvin" Cc: Atsushi Kumagai Cc: Chris Metcalf Cc: Dave Anderson Cc: Eric Biederman Cc: Guan Xuetao Cc: Ingo Molnar Cc: Vivek Goyal Signed-off-by: Andrew Morton --- mm/vmalloc.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 1d9878b7cf52..1bf94ad452b6 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1290,12 +1290,14 @@ struct vm_struct *vmlist; static void setup_vmalloc_vm(struct vm_struct *vm, struct vmap_area *va, unsigned long flags, const void *caller) { + spin_lock(&vmap_area_lock); vm->flags = flags; vm->addr = (void *)va->va_start; vm->size = va->va_end - va->va_start; vm->caller = caller; va->vm = vm; va->flags |= VM_VM_AREA; + spin_unlock(&vmap_area_lock); } static void insert_vmalloc_vmlist(struct vm_struct *vm) @@ -1447,6 +1449,11 @@ struct vm_struct *remove_vm_area(const void *addr) if (va && va->flags & VM_VM_AREA) { struct vm_struct *vm = va->vm; + spin_lock(&vmap_area_lock); + va->vm = NULL; + va->flags &= ~VM_VM_AREA; + spin_unlock(&vmap_area_lock); + if (!(vm->flags & VM_UNLIST)) { struct vm_struct *tmp, **p; /* -- 2.39.5