From: Linus Torvalds <torvalds@linux-foundation.org>
To: Johannes Weiner <hannes@saeurebad.de>
Cc: Alexey Dobriyan <adobriyan@gmail.com>,
akpm@linuxfoundation.org, torvalds@linuxfoundation.org,
npiggin@suse.de, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86: do not overrun page table ranges in gup
Date: Mon, 28 Jul 2008 17:39:18 -0700 (PDT) [thread overview]
Message-ID: <alpine.LFD.1.10.0807281737480.3486@nehalem.linux-foundation.org> (raw)
In-Reply-To: <alpine.LFD.1.10.0807281721200.3486@nehalem.linux-foundation.org>
On Mon, 28 Jul 2008, Linus Torvalds wrote:
>
> So no, the right fix would be to align 'start' first, which means that
> everything else (including 'end') will be page-aligned. Aligning just one
> or the other is very very wrong.
Does this work?
Not pretty, but it stands _some_ chance of being correct.
Linus
---
arch/x86/mm/gup.c | 9 ++++++---
1 files changed, 6 insertions(+), 3 deletions(-)
diff --git a/arch/x86/mm/gup.c b/arch/x86/mm/gup.c
index 3085f25..007bb06 100644
--- a/arch/x86/mm/gup.c
+++ b/arch/x86/mm/gup.c
@@ -223,14 +223,17 @@ int get_user_pages_fast(unsigned long start, int nr_pages, int write,
struct page **pages)
{
struct mm_struct *mm = current->mm;
- unsigned long end = start + (nr_pages << PAGE_SHIFT);
- unsigned long addr = start;
+ unsigned long addr, len, end;
unsigned long next;
pgd_t *pgdp;
int nr = 0;
+ start &= PAGE_MASK;
+ addr = start;
+ len = (unsigned long) nr_pages << PAGE_SHIFT;
+ end = start + len;
if (unlikely(!access_ok(write ? VERIFY_WRITE : VERIFY_READ,
- start, nr_pages*PAGE_SIZE)))
+ start, len)))
goto slow_irqon;
/*
next prev parent reply other threads:[~2008-07-29 0:42 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-07-28 18:49 2.6.26-$sha1: RIP gup_pte_range+0x54/0x120 Alexey Dobriyan
2008-07-28 18:53 ` Alexey Dobriyan
2008-07-29 0:00 ` [PATCH] x86: do not overrun page table ranges in gup Johannes Weiner
2008-07-29 0:18 ` Johannes Weiner
2008-07-29 0:33 ` Linus Torvalds
2008-07-29 0:39 ` Linus Torvalds [this message]
2008-07-29 0:51 ` Alexey Dobriyan
2008-07-29 1:25 ` Hugh Dickins
2008-07-29 1:37 ` Nick Piggin
2008-07-29 0:53 ` Johannes Weiner
2008-07-29 1:39 ` Nick Piggin
2008-07-29 0:26 ` Alexey Dobriyan
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