From: Nitin Gupta <nitin.m.gupta@oracle.com>
Date: Fri, 23 Jun 2017 00:15:08 +0000 (-0700)
Subject: sparc64: Fix gup_huge_pmd
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=dbd2667a4fb9ce4f547982b07cd69dda127c47ea;p=linux.git

sparc64: Fix gup_huge_pmd

The function assumes that each PMD points to head of a
huge page. This is not correct as a PMD can point to
start of any 8M region with a, say 256M, hugepage. The
fix ensures that it points to the correct head of any PMD
huge page.

Cc: Julian Calaby <julian.calaby@gmail.com>
Signed-off-by: Nitin Gupta <nitin.m.gupta@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

diff --git a/arch/sparc/mm/gup.c b/arch/sparc/mm/gup.c
index cd0e32bbcb1de..f80cfc64c55ba 100644
--- a/arch/sparc/mm/gup.c
+++ b/arch/sparc/mm/gup.c
@@ -78,8 +78,8 @@ static int gup_huge_pmd(pmd_t *pmdp, pmd_t pmd, unsigned long addr,
 		return 0;
 
 	refs = 0;
-	head = pmd_page(pmd);
-	page = head + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
+	page = pmd_page(pmd) + ((addr & ~PMD_MASK) >> PAGE_SHIFT);
+	head = compound_head(page);
 	do {
 		VM_BUG_ON(compound_head(page) != head);
 		pages[*nr] = page;