Patch "sparc64: Fix gup_huge_pmd" has been added to the 4.12-stable tree

Patch "sparc64: Fix gup_huge_pmd" has been added to the 4.12-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    sparc64: Fix gup_huge_pmd

to the 4.12-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     sparc64-fix-gup_huge_pmd.patch
and it can be found in the queue-4.12 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Tue Jul 18 09:36:30 CEST 2017
From: Nitin Gupta <nitin.m.gupta@oracle.com>
Date: Thu, 22 Jun 2017 17:15:08 -0700
Subject: sparc64: Fix gup_huge_pmd

From: Nitin Gupta <nitin.m.gupta@oracle.com>


[ Upstream commit dbd2667a4fb9ce4f547982b07cd69dda127c47ea ]

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/sparc/mm/gup.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- 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
 		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;


Patches currently in stable-queue which might be from nitin.m.gupta@oracle.com are

queue-4.12/sparc64-fix-gup_huge_pmd.patch