Re: FAILED: patch "[PATCH] iommu/io-pgtable-arm: Ensure we free the final level on" failed to apply to 4.4-stable tree

[Will Deacon <will.deacon@arm.com>]

On Wed, Jan 27, 2016 at 09:57:36AM -0800, Greg KH wrote:
> On Wed, Jan 27, 2016 at 11:59:01AM +0000, Will Deacon wrote:
> > On Tue, Jan 26, 2016 at 10:48:23PM -0800, gregkh@linuxfoundation.org wrote:
> > > 
> > > The patch below does not apply to the 4.4-stable tree.
> > > If someone wants it applied there, or to any other stable or longterm
> > > tree, then please email the backport, including the original git commit
> > > id to <stable@vger.kernel.org>.
> > 
> > Do you have the conflict handy? It applies to 4.4 here, so I guess its
> > somehow conflicting with another -stable patch, but I couldn't spot it.
> 
> The whole thing fails to apply:
> 
> Applying iommu-io-pgtable-arm-ensure-we-free-the-final-level-on-teardown.patch to linux-4.4.y
> Applying patch iommu-io-pgtable-arm-ensure-we-free-the-final-level-on-teardown.patch
> patching file drivers/iommu/io-pgtable-arm.c
> Hunk #1 FAILED at 404.
> 1 out of 1 hunk FAILED -- rejects in file drivers/iommu/io-pgtable-arm.c
> 
> It also doesn't apply to a clean 4.4 tree for me either:
> 
> ~/linux/stable $ git clone -s linux-4.4.y/ x
> Cloning into 'x'...
> done.
> Checking out files: 100% (52221/52221), done.
> ~/linux/stable $ cd x
> ~/linux/stable/x $ git show --pretty=email 12c2ab09571e8aae3a87da2a4a452632a5fac1e5 > x.patch
> ~/linux/stable/x $ patch -p1 --dry-run < x.patch
> checking file drivers/iommu/io-pgtable-arm.c
> Hunk #1 FAILED at 404.
> 1 out of 1 hunk FAILED
> 
> How are you applying this?

$ git cherry-pick 12c2ab09571e8aae3a87da2a4a452632a5fac1e5

It looks like there's a small change in context that patch doesn't like.
Updated patch below.

Will

--->8

>From 5ac63eeb89e736553a1fd728645d61abdfb04c72 Mon Sep 17 00:00:00 2001
From: Will Deacon <will.deacon@arm.com>
Date: Tue, 15 Dec 2015 16:08:12 +0000
Subject: [PATCH] iommu/io-pgtable-arm: Ensure we free the final level on
 teardown

When tearing down page tables, we return early for the final level
since we know that we won't have any table pointers to follow.
Unfortunately, this also means that we forget to free the final level,
so we end up leaking memory.

Fix the issue by always freeing the current level, but just don't bother
to iterate over the ptes if we're at the final level.

Cc: <stable@vger.kernel.org>
Reported-by: Zhang Bo <zhangbo_a@xiaomi.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
---
 drivers/iommu/io-pgtable-arm.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/drivers/iommu/io-pgtable-arm.c b/drivers/iommu/io-pgtable-arm.c
index 7df97777662d..dad768caa9c5 100644
--- a/drivers/iommu/io-pgtable-arm.c
+++ b/drivers/iommu/io-pgtable-arm.c
@@ -405,17 +405,18 @@ static void __arm_lpae_free_pgtable(struct arm_lpae_io_pgtable *data, int lvl,
 	arm_lpae_iopte *start, *end;
 	unsigned long table_size;
 
-	/* Only leaf entries at the last level */
-	if (lvl == ARM_LPAE_MAX_LEVELS - 1)
-		return;
-
 	if (lvl == ARM_LPAE_START_LVL(data))
 		table_size = data->pgd_size;
 	else
 		table_size = 1UL << data->pg_shift;
 
 	start = ptep;
-	end = (void *)ptep + table_size;
+
+	/* Only leaf entries at the last level */
+	if (lvl == ARM_LPAE_MAX_LEVELS - 1)
+		end = ptep;
+	else
+		end = (void *)ptep + table_size;
 
 	while (ptep != end) {
 		arm_lpae_iopte pte = *ptep++;
-- 
2.1.4