If we allocate anon_vma_chain before starting to link, we can reduce
the lock hold time. This patch implement it.
Signed-off-by: Joonsoo Kim <iamjoonsoo....@lge.com>
diff --git a/mm/rmap.c b/mm/rmap.c
index c2f51cb..1603f64 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -240,18 +240,21 @@ int anon_vma_clone(struct vm_area_struct *dst, struct
vm_area_struct *src)
{
struct anon_vma_chain *avc, *pavc;
struct anon_vma *root = NULL;
+ LIST_HEAD(avc_list);
+
+ list_for_each_entry(pavc, &src->anon_vma_chain, same_vma) {
+ avc = anon_vma_chain_alloc(GFP_KERNEL);
+ if (unlikely(!avc))
+ goto enomem_failure;
+
+ list_add_tail(&avc->same_vma, &avc_list);
+ }
list_for_each_entry_reverse(pavc, &src->anon_vma_chain, same_vma) {
struct anon_vma *anon_vma;
- avc = anon_vma_chain_alloc(GFP_NOWAIT | __GFP_NOWARN);
- if (unlikely(!avc)) {
- unlock_anon_vma_root(root);
- root = NULL;
- avc = anon_vma_chain_alloc(GFP_KERNEL);
- if (!avc)
- goto enomem_failure;
- }
+ avc = list_entry((&avc_list)->next, typeof(*avc), same_vma);
+ list_del(&avc->same_vma);
anon_vma = pavc->anon_vma;
root = lock_anon_vma_root(root, anon_vma);
anon_vma_chain_link(dst, avc, anon_vma);
@@ -259,8 +262,11 @@ int anon_vma_clone(struct vm_area_struct *dst, struct
vm_area_struct *src)
unlock_anon_vma_root(root);
return 0;
- enomem_failure:
- unlink_anon_vmas(dst);
+enomem_failure:
+ list_for_each_entry_safe(avc, pavc, &avc_list, same_vma) {
+ list_del(&avc->same_vma);
+ anon_vma_chain_free(avc);
+ }
return -ENOMEM;
}
--
1.7.9.5
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