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Subject[ 20/20] hugetlb: fix resv_map leak in error path
3.0-stable review patch.  If anyone has any objections, please let me know.

------------------
From: Dave Hansen <dave@linux.vnet.ibm.com>

commit c50ac050811d6485616a193eb0f37bfbd191cc89 and
4523e1458566a0e8ecfaff90f380dd23acc44d27 upstream.

When called for anonymous (non-shared) mappings, hugetlb_reserve_pages()
does a resv_map_alloc(). It depends on code in hugetlbfs's
vm_ops->close() to release that allocation.

However, in the mmap() failure path, we do a plain unmap_region() without
the remove_vma() which actually calls vm_ops->close().

This is a decent fix. This leak could get reintroduced if new code (say,
after hugetlb_reserve_pages() in hugetlbfs_file_mmap()) decides to return
an error. But, I think it would have to unroll the reservation anyway.

Christoph's test case:

http://marc.info/?l=linux-mm&m=133728900729735

This patch applies to 3.4 and later. A version for earlier kernels is at
https://lkml.org/lkml/2012/5/22/418.

Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reported-by: Christoph Lameter <cl@linux.com>
Tested-by: Christoph Lameter <cl@linux.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>


---
mm/hugetlb.c | 29 +++++++++++++++++++++++------
1 file changed, 23 insertions(+), 6 deletions(-)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2060,6 +2060,15 @@ static void hugetlb_vm_op_open(struct vm
kref_get(&reservations->refs);
}

+static void resv_map_put(struct vm_area_struct *vma)
+{
+ struct resv_map *reservations = vma_resv_map(vma);
+
+ if (!reservations)
+ return;
+ kref_put(&reservations->refs, resv_map_release);
+}
+
static void hugetlb_vm_op_close(struct vm_area_struct *vma)
{
struct hstate *h = hstate_vma(vma);
@@ -2075,7 +2084,7 @@ static void hugetlb_vm_op_close(struct v
reserve = (end - start) -
region_count(&reservations->regions, start, end);

- kref_put(&reservations->refs, resv_map_release);
+ resv_map_put(vma);

if (reserve) {
hugetlb_acct_memory(h, -reserve);
@@ -2877,12 +2886,16 @@ int hugetlb_reserve_pages(struct inode *
set_vma_resv_flags(vma, HPAGE_RESV_OWNER);
}

- if (chg < 0)
- return chg;
+ if (chg < 0) {
+ ret = chg;
+ goto out_err;
+ }

/* There must be enough filesystem quota for the mapping */
- if (hugetlb_get_quota(inode->i_mapping, chg))
- return -ENOSPC;
+ if (hugetlb_get_quota(inode->i_mapping, chg)) {
+ ret = -ENOSPC;
+ goto out_err;
+ }

/*
* Check enough hugepages are available for the reservation.
@@ -2891,7 +2904,7 @@ int hugetlb_reserve_pages(struct inode *
ret = hugetlb_acct_memory(h, chg);
if (ret < 0) {
hugetlb_put_quota(inode->i_mapping, chg);
- return ret;
+ goto out_err;
}

/*
@@ -2908,6 +2921,10 @@ int hugetlb_reserve_pages(struct inode *
if (!vma || vma->vm_flags & VM_MAYSHARE)
region_add(&inode->i_mapping->private_list, from, to);
return 0;
+out_err:
+ if (vma)
+ resv_map_put(vma);
+ return ret;
}

void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)



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