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Commit c50ac050 authored by Dave Hansen's avatar Dave Hansen Committed by Linus Torvalds
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hugetlb: fix resv_map leak in error path 

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: default avatarDave Hansen <dave@linux.vnet.ibm.com>
Acked-by: default avatarMel Gorman <mel@csn.ul.ie>
Acked-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reported-by: default avatarChristoph Lameter <cl@linux.com>
Tested-by: default avatarChristoph Lameter <cl@linux.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org>	[2.6.32+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 5c2b8a16

mm/hugetlb.c

+22 −6
Original line number Diff line number Diff line
@@ -2157,6 +2157,15 @@ static void hugetlb_vm_op_open(struct vm_area_struct *vma) 
		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);
@@ -2173,7 +2182,7 @@ static void hugetlb_vm_op_close(struct vm_area_struct *vma) 
		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);
@@ -2991,12 +3000,16 @@ int hugetlb_reserve_pages(struct inode *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 pages in the subpool for the mapping */

	if (hugepage_subpool_get_pages(spool, chg))

		return -ENOSPC;

	if (hugepage_subpool_get_pages(spool, chg)) {

		ret = -ENOSPC;

		goto out_err;

	}



	/*

	 * Check enough hugepages are available for the reservation.
@@ -3005,7 +3018,7 @@ int hugetlb_reserve_pages(struct inode *inode, 
	ret = hugetlb_acct_memory(h, chg);

	if (ret < 0) {

		hugepage_subpool_put_pages(spool, chg);

		return ret;

		goto out_err;

	}



	/*
@@ -3022,6 +3035,9 @@ int hugetlb_reserve_pages(struct inode *inode, 
	if (!vma || vma->vm_flags & VM_MAYSHARE)

		region_add(&inode->i_mapping->private_list, from, to);

	return 0;

out_err:

	resv_map_put(vma);

	return ret;

}



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