Commit f27a5136 authored by Mike Kravetz's avatar Mike Kravetz Committed by Linus Torvalds
Browse files

hugetlbfs: always use address space in inode for resv_map pointer 

Continuing discussion about 58b6e5e8 ("hugetlbfs: fix memory leak for
resv_map") brought up the issue that inode->i_mapping may not point to the
address space embedded within the inode at inode eviction time.  The
hugetlbfs truncate routine handles this by explicitly using inode->i_data.
However, code cleaning up the resv_map will still use the address space
pointed to by inode->i_mapping.  Luckily, private_data is NULL for address
spaces in all such cases today but, there is no guarantee this will
continue.

Change all hugetlbfs code getting a resv_map pointer to explicitly get it
from the address space embedded within the inode.  In addition, add more
comments in the code to indicate why this is being done.

Link: http://lkml.kernel.org/r/20190419204435.16984-1-mike.kravetz@oracle.com


Signed-off-by: default avatarMike Kravetz <mike.kravetz@oracle.com>
Reported-by: default avatarYufen Yu <yuyufen@huawei.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1f862989

fs/hugetlbfs/inode.c

+9 −2
Original line number Diff line number Diff line
@@ -497,8 +497,15 @@ static void hugetlbfs_evict_inode(struct inode *inode) 
	struct resv_map *resv_map;



	remove_inode_hugepages(inode, 0, LLONG_MAX);

	resv_map = (struct resv_map *)inode->i_mapping->private_data;

	/* root inode doesn't have the resv_map, so we should check it */



	/*

	 * Get the resv_map from the address space embedded in the inode.

	 * This is the address space which points to any resv_map allocated

	 * at inode creation time.  If this is a device special inode,

	 * i_mapping may not point to the original address space.

	 */

	resv_map = (struct resv_map *)(&inode->i_data)->private_data;

	/* Only regular and link inodes have associated reserve maps */

	if (resv_map)

		resv_map_release(&resv_map->refs);

	clear_inode(inode);

mm/hugetlb.c

+18 −1
Original line number Diff line number Diff line
@@ -740,7 +740,15 @@ void resv_map_release(struct kref *ref) 


static inline struct resv_map *inode_resv_map(struct inode *inode)

{

	return inode->i_mapping->private_data;

	/*

	 * At inode evict time, i_mapping may not point to the original

	 * address space within the inode.  This original address space

	 * contains the pointer to the resv_map.  So, always use the

	 * address space embedded within the inode.

	 * The VERY common case is inode->mapping == &inode->i_data but,

	 * this may not be true for device special inodes.

	 */

	return (struct resv_map *)(&inode->i_data)->private_data;

}



static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
@@ -4518,6 +4526,11 @@ int hugetlb_reserve_pages(struct inode *inode, 
	 * called to make the mapping read-write. Assume !vma is a shm mapping

	 */

	if (!vma || vma->vm_flags & VM_MAYSHARE) {

		/*

		 * resv_map can not be NULL as hugetlb_reserve_pages is only

		 * called for inodes for which resv_maps were created (see

		 * hugetlbfs_get_inode).

		 */

		resv_map = inode_resv_map(inode);



		chg = region_chg(resv_map, from, to);
@@ -4609,6 +4622,10 @@ long hugetlb_unreserve_pages(struct inode *inode, long start, long end, 
	struct hugepage_subpool *spool = subpool_inode(inode);

	long gbl_reserve;



	/*

	 * Since this routine can be called in the evict inode path for all

	 * hugetlbfs inodes, resv_map could be NULL.

	 */

	if (resv_map) {

		chg = region_del(resv_map, start, end);

		/*

CRA Git | Maintained and supported by SUSTech CRA and CCSE