From: Linus Torvalds <torvalds@g5.osdl.org>
Date: Tue, 13 Dec 2005 00:24:33 +0000 (-0800)
Subject: get_user_pages: don't try to follow PFNMAP pages
X-Git-Tag: v2.6.15-rc6~99
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1ff8038988adecfde71d82c0597727fc239d4e8c;p=linux-2.6

get_user_pages: don't try to follow PFNMAP pages

Nick Piggin points out that a few drivers play games with VM_IO (why?
who knows..) and thus a pfn-remapped area may not have that bit set even
if remap_pfn_range() set it originally.

So make it explicit in get_user_pages() that we don't follow VM_PFNMAP
pages, since pretty much by definition they do not have a "struct page"
associated with them.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---

diff --git a/mm/memory.c b/mm/memory.c
index 47c533eaa0..d22f78c8a3 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1009,7 +1009,7 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 			continue;
 		}
 
-		if (!vma || (vma->vm_flags & VM_IO)
+		if (!vma || (vma->vm_flags & (VM_IO | VM_PFNMAP))
 				|| !(vm_flags & vma->vm_flags))
 			return i ? : -EFAULT;