Re: Please add 98fb1ffd8154890d7051750e61ff5548c3ee2ab2

[Luis Henriques <luis.henriques@canonical.com>]

On Tue, Sep 15, 2015 at 04:48:07PM +0200, Richard Weinberger wrote:
> Hi!
> 
> Can you please add this commit to stable?
> commit 98fb1ffd8154890d7051750e61ff5548c3ee2ab2
> Author: Kevin Cernekee <cernekee@chromium.org>
> Date:   Wed Apr 22 09:30:53 2015 -0300
> 
>     UBI: block: Add missing cache flushes
> 
> The fix affects all kernels >= v3.15.
> 

I was trying to apply this commit to 3.16, but it requires a backport.
Could you please confirm the following backport is correct?  It can
probably be applied to other stable kernels, but I haven't check.

Cheers,
--
Lu�s

>From e781e504616d2652e9fc11f6536dd8be221298f9 Mon Sep 17 00:00:00 2001
From: Kevin Cernekee <cernekee@chromium.org>
Date: Wed, 22 Apr 2015 09:30:53 -0300
Subject: [PATCH] UBI: block: Add missing cache flushes

commit 98fb1ffd8154890d7051750e61ff5548c3ee2ab2 upstream.

Block drivers are responsible for calling flush_dcache_page() on each
BIO request. This operation keeps the I$ coherent with the D$ on
architectures that don't have hardware coherency support. Without this
flush, random crashes are seen when executing user programs from an ext4
filesystem backed by a ubiblock device.

This patch is based on the change implemented in commit 2d4dc890b5c8
("block: add helpers to run flush_dcache_page() against a bio and a
request's pages").

Fixes: 9d54c8a33eec ("UBI: R/O block driver on top of UBI volumes")
Signed-off-by: Kevin Cernekee <cernekee@chromium.org>
Signed-off-by: Ezequiel Garcia <ezequiel.garcia@imgtec.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
 drivers/mtd/ubi/block.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/mtd/ubi/block.c b/drivers/mtd/ubi/block.c
index 8457df7ec5af..d3fbda7eae98 100644
--- a/drivers/mtd/ubi/block.c
+++ b/drivers/mtd/ubi/block.c
@@ -275,6 +275,7 @@ static void ubiblock_do_work(struct work_struct *work)
 		spin_unlock_irq(rq->queue_lock);
 		res = do_ubiblock_request(dev, req);
 		spin_lock_irq(rq->queue_lock);
+		rq_flush_dcache_pages(req);
 
 		/*
 		 * If we're done with this request,