Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     Boris Brezillon <boris.brezillon@bootlin.com>
CC:     Ben Hutchings <ben.hutchings@codethink.co.uk>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "stable@vger.kernel.org" <stable@vger.kernel.org>,
        Sascha Hauer <s.hauer@pengutronix.de>,
        Richard Weinberger <richard@nod.at>,
        Boris Brezillon <boris.brezillon@free-electrons.com>
Subject: Re: [PATCH 4.4 03/34] mtd: nand: gpmi: Fix failure when a erased page
 has a bitflip at BBM
Thread-Topic: [PATCH 4.4 03/34] mtd: nand: gpmi: Fix failure when a erased
 page has a bitflip at BBM
Thread-Index: AQHTsgQtgovGbdiw4U+JNRdUpxG2GqPDvm8AgAC1ogCAAHFdAA==
Date:   Wed, 7 Mar 2018 14:58:21 +0000
Message-ID: <20180307145820.a6p7g4zzw4phdb66@sasha-lappy>
References: <20180302084435.842679610@linuxfoundation.org>
 <20180302084436.171257760@linuxfoundation.org>
 <1520371350.23626.23.camel@codethink.co.uk>
 <20180307091236.741b7fd2@bbrezillon>
In-Reply-To: <20180307091236.741b7fd2@bbrezillon>
Accept-Language: en-US
Content-Language: en-US
received-spf: None (protection.outlook.com: microsoft.com does not designate
 permitted sender hosts)
spamdiagnosticoutput: 1:99
spamdiagnosticmetadata: NSPM
Content-Type: text/plain; charset="iso-8859-1"
Content-ID: <E523F9C7B253374391BEE76ADB475050@namprd21.prod.outlook.com>
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
X-MS-Exchange-CrossTenant-Network-Message-Id: 107fe08c-db08-4d68-99d4-08d5843bdeaf
X-MS-Exchange-CrossTenant-originalarrivaltime: 07 Mar 2018 14:58:21.5389
 (UTC)
X-MS-Exchange-CrossTenant-fromentityheader: Hosted
X-MS-Exchange-CrossTenant-id: 72f988bf-86f1-41af-91ab-2d7cd011db47
X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM5PR2101MB1032
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Wed, Mar 07, 2018 at 09:12:36AM +0100, Boris Brezillon wrote:
>On Tue, 06 Mar 2018 21:22:30 +0000
>Ben Hutchings <ben.hutchings@codethink.co.uk> wrote:
>
>> On Fri, 2018-03-02 at 09:50 +0100, Greg Kroah-Hartman wrote:
>> > 4.4-stable review patch.=A0=A0If anyone has any objections, please let=
 me know.
>> >
>> > ------------------
>> >
>> > From: Sascha Hauer <s.hauer@pengutronix.de>
>> >
>> >
>> > [ Upstream commit fdf2e821052958a114618a95ab18a300d0b080cb ]
>> >
>> > When erased subpages are read then the BCH decoder returns STATUS_ERAS=
ED
>> > if they are all empty, or STATUS_UNCORRECTABLE if there are bitflips.
>> > When there are bitflips, we have to set these bits again to show the
>> > upper layers a completely erased page. When a bitflip happens in the
>> > exact byte where the bad block marker is, then this byte is swapped
>> > with another byte in block_mark_swapping(). The correction code then
>> > detects a bitflip in another subpage and no longer corrects the bitfli=
p
>> > where it really happens.
>> [...]
>>
>> This seesm to be a bug fix for commit bd2e778c9ee3 "gpmi-nand: Handle
>> ECC Errors in erased pages".  That's not in 4.4 so the bug fix is not
>> needed, though it doesn't appear to do any harm.
>
>I wonder why the fix was backported to stable releases in the first
>place. AFAICS, there's no Cc-stable or Fixes tag in the original
>commit. It's probably something in the backport-to-stable process I'm
>not aware of.

It's an attempt to mine kernel commits for commits that should go into
stable trees but were not marked as such.

Thanks again for the review!

--=20

Thanks,
Sasha=