mm, THP: clean up return value of madvise_free_huge_pmd

The definition of return value of madvise_free_huge_pmd is not clear
before.  According to the suggestion of Minchan Kim, change the type of
return value to bool and return true if we do MADV_FREE successfully on
entire pmd page, otherwise, return false.  Comments are added too.

Link: http://lkml.kernel.org/r/1467135452-16688-2-git-send-email-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Ebru Akagunduz <ebru.akagunduz@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 92ce91c..6f14de4 100644 (file)
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -11,7 +11,7 @@ extern struct page *follow_trans_huge_pmd(struct vm_area_struct *vma,
                                          unsigned long addr,
                                          pmd_t *pmd,
                                          unsigned int flags);
-extern int madvise_free_huge_pmd(struct mmu_gather *tlb,
+extern bool madvise_free_huge_pmd(struct mmu_gather *tlb,
                        struct vm_area_struct *vma,
                        pmd_t *pmd, unsigned long addr, unsigned long next);
 extern int zap_huge_pmd(struct mmu_gather *tlb,

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 121a7f8..8f0cd35 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1249,25 +1249,26 @@ out:
        return 0;
 }
 
-int madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
+/*
+ * Return true if we do MADV_FREE successfully on entire pmd page.
+ * Otherwise, return false.
+ */
+bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
                pmd_t *pmd, unsigned long addr, unsigned long next)
-
 {
        spinlock_t *ptl;
        pmd_t orig_pmd;
        struct page *page;
        struct mm_struct *mm = tlb->mm;
-       int ret = 0;
+       bool ret = false;
 
        ptl = pmd_trans_huge_lock(pmd, vma);
        if (!ptl)
                goto out_unlocked;
 
        orig_pmd = *pmd;
-       if (is_huge_zero_pmd(orig_pmd)) {
-               ret = 1;
+       if (is_huge_zero_pmd(orig_pmd))
                goto out;
-       }
 
        page = pmd_page(orig_pmd);
        /*
@@ -1309,7 +1310,7 @@ int madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
                set_pmd_at(mm, addr, pmd, orig_pmd);
                tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
        }
-       ret = 1;
+       ret = true;
 out:
        spin_unlock(ptl);
 out_unlocked: