From: Hugh Dickins <hugh@veritas.com>
Date: Sun, 8 Feb 2009 20:56:58 +0000 (+0000)
Subject: mm: fix error case in mlock downgrade reversion
X-Git-Tag: v2.6.28.5~13
X-Git-Url: https://git.karo-electronics.de/?a=commitdiff_plain;h=7bf97ba5bb635e84e2092d4de4092dcf76ad82a0;p=karo-tx-linux.git

mm: fix error case in mlock downgrade reversion

commit d5b562330ec766292a3ac54ae5e0673610bd5b3d upstream.

Commit 27421e211a39784694b597dbf35848b88363c248, Manually revert
"mlock: downgrade mmap sem while populating mlocked regions", has
introduced its own regression: __mlock_vma_pages_range() may report
an error (for example, -EFAULT from trying to lock down pages from
beyond EOF), but mlock_vma_pages_range() must hide that from its
callers as before.

Reported-by: Sami Farin <safari-kernel@safari.iki.fi>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

diff --git a/mm/mlock.c b/mm/mlock.c
index 13e0f9af3bd1..64dca47c5cbe 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -310,7 +310,10 @@ long mlock_vma_pages_range(struct vm_area_struct *vma,
 			is_vm_hugetlb_page(vma) ||
 			vma == get_gate_vma(current))) {
 
-		return __mlock_vma_pages_range(vma, start, end, 1);
+		__mlock_vma_pages_range(vma, start, end, 1);
+
+		/* Hide errors from mmap() and other callers */
+		return 0;
 	}
 
 	/*