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authorMike Kravetz <mike.kravetz@oracle.com>2015-09-08 15:01:44 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-09-08 15:35:28 -0700
commit1fb1b0e9ef2d661488f8053986c3b7641cae529d (patch)
tree4fe154e4347f43f023d33065db9170c81d835e18 /mm/hugetlb.c
parentb5cec28d36f5ee6b4e6f68a0a40aa1e4045d6d99 (diff)
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mm/hugetlb: vma_has_reserves() needs to handle fallocate hole punch
In vma_has_reserves(), the current assumption is that reserves are always present for shared mappings. However, this will not be the case with fallocate hole punch. When punching a hole, the present page will be deleted as well as the region/reserve map entry (and hence any reservation). vma_has_reserves is passed "chg" which indicates whether or not a region/reserve map is present. Use this to determine if reserves are actually present or were removed via hole punch. Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Rientjes <rientjes@google.com> Cc: Hugh Dickins <hughd@google.com> Cc: Davidlohr Bueso <dave@stgolabs.net> Cc: Aneesh Kumar <aneesh.kumar@linux.vnet.ibm.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/hugetlb.c')
-rw-r--r--mm/hugetlb.c15
1 files changed, 13 insertions, 2 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 61c52cd5f77b..bd12e8c8bc7b 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -801,8 +801,19 @@ static bool vma_has_reserves(struct vm_area_struct *vma, long chg)
}
/* Shared mappings always use reserves */
- if (vma->vm_flags & VM_MAYSHARE)
- return true;
+ if (vma->vm_flags & VM_MAYSHARE) {
+ /*
+ * We know VM_NORESERVE is not set. Therefore, there SHOULD
+ * be a region map for all pages. The only situation where
+ * there is no region map is if a hole was punched via
+ * fallocate. In this case, there really are no reverves to
+ * use. This situation is indicated if chg != 0.
+ */
+ if (chg)
+ return false;
+ else
+ return true;
+ }
/*
* Only the process that called mmap() has reserves for