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-rw-r--r--mm/hugetlb.c35
1 files changed, 16 insertions, 19 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index b94752ae791b..e84d22ce5de8 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2808,7 +2808,7 @@ static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
{
struct hstate *h = hstate_vma(vma);
struct page *old_page, *new_page;
- int outside_reserve = 0;
+ int ret = 0, outside_reserve = 0;
unsigned long mmun_start; /* For mmu_notifiers */
unsigned long mmun_end; /* For mmu_notifiers */
@@ -2838,14 +2838,14 @@ retry_avoidcopy:
page_cache_get(old_page);
- /* Drop page table lock as buddy allocator may be called */
+ /*
+ * Drop page table lock as buddy allocator may be called. It will
+ * be acquired again before returning to the caller, as expected.
+ */
spin_unlock(ptl);
new_page = alloc_huge_page(vma, address, outside_reserve);
if (IS_ERR(new_page)) {
- long err = PTR_ERR(new_page);
- page_cache_release(old_page);
-
/*
* If a process owning a MAP_PRIVATE mapping fails to COW,
* it is due to references held by a child and an insufficient
@@ -2854,6 +2854,7 @@ retry_avoidcopy:
* may get SIGKILLed if it later faults.
*/
if (outside_reserve) {
+ page_cache_release(old_page);
BUG_ON(huge_pte_none(pte));
unmap_ref_private(mm, vma, old_page, address);
BUG_ON(huge_pte_none(pte));
@@ -2869,12 +2870,9 @@ retry_avoidcopy:
return 0;
}
- /* Caller expects lock to be held */
- spin_lock(ptl);
- if (err == -ENOMEM)
- return VM_FAULT_OOM;
- else
- return VM_FAULT_SIGBUS;
+ ret = (PTR_ERR(new_page) == -ENOMEM) ?
+ VM_FAULT_OOM : VM_FAULT_SIGBUS;
+ goto out_release_old;
}
/*
@@ -2882,11 +2880,8 @@ retry_avoidcopy:
* anon_vma prepared.
*/
if (unlikely(anon_vma_prepare(vma))) {
- page_cache_release(new_page);
- page_cache_release(old_page);
- /* Caller expects lock to be held */
- spin_lock(ptl);
- return VM_FAULT_OOM;
+ ret = VM_FAULT_OOM;
+ goto out_release_all;
}
copy_user_huge_page(new_page, old_page, address, vma,
@@ -2896,6 +2891,7 @@ retry_avoidcopy:
mmun_start = address & huge_page_mask(h);
mmun_end = mmun_start + huge_page_size(h);
mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
+
/*
* Retake the page table lock to check for racing updates
* before the page tables are altered
@@ -2916,12 +2912,13 @@ retry_avoidcopy:
}
spin_unlock(ptl);
mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
+out_release_all:
page_cache_release(new_page);
+out_release_old:
page_cache_release(old_page);
- /* Caller expects lock to be held */
- spin_lock(ptl);
- return 0;
+ spin_lock(ptl); /* Caller expects lock to be held */
+ return ret;
}
/* Return the pagecache page at a given address within a VMA */
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