hugetlb: try to search again if it is really needed

Search again only if some holes may be skipped in the first pass.

[akpm@linux-foundation.org: clean up crazy compound definition]
Signed-off-by: NXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/x86/mm/hugetlbpage.c

@@ -309,9 +309,10 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 	struct hstate *h = hstate_file(file);
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma, *prev_vma;
-	unsigned long base = mm->mmap_base, addr = addr0;
+	unsigned long base = mm->mmap_base;
+	unsigned long addr = addr0;
 	unsigned long largest_hole = mm->cached_hole_size;
-	int first_time = 1;
+	unsigned long start_addr;
 
 	/* don't allow allocations above current base */
 	if (mm->free_area_cache > base)
@@ -322,6 +323,8 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 		mm->free_area_cache  = base;
 	}
 try_again:
+	start_addr = mm->free_area_cache;
+
 	/* make sure it can fit in the remaining address space */
 	if (mm->free_area_cache < len)
 		goto fail;
@@ -368,10 +371,9 @@ static unsigned long hugetlb_get_unmapped_area_topdown(struct file *file,
 	 * if hint left us with no space for the requested
 	 * mapping then try again:
 	 */
-	if (first_time) {
+	if (start_addr != base) {
 		mm->free_area_cache = base;
 		largest_hole = 0;
-		first_time = 0;
 		goto try_again;
 	}
 	/*