From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lilium.sigma-star.at ([109.75.188.150]) by bombadil.infradead.org with esmtps (Exim 4.89 #1 (Red Hat Linux)) id 1erhZf-0002Zs-PM for linux-mtd@lists.infradead.org; Fri, 02 Mar 2018 10:06:02 +0000 From: Richard Weinberger To: Tim Harvey Cc: Artem Bityutskiy , Adrian Hunter , linux-mtd@lists.infradead.org, Koen Vandeputte , Scott Bowman Subject: Re: Does modern UBI/UBIFS still suffer from the 'unstable bits issue'? Date: Fri, 02 Mar 2018 11:07:10 +0100 Message-ID: <4813843.hImRYGMsqb@blindfold> In-Reply-To: References: <9684795.NoKKx6Kvh2@blindfold> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="iso-8859-1" List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Tim, Am Freitag, 2. M=E4rz 2018, 02:19:54 CET schrieb Tim Harvey: > On Thu, Mar 1, 2018 at 8:32 AM, Richard Weinberger wrote: > > Tim, > >=20 > > Am Donnerstag, 1. M=E4rz 2018, 17:15:44 CET schrieb Tim Harvey: > >> Greetings, > >>=20 > >> I have a user with an IMX6 and raw NAND using UBI/UBIFS who has been > >=20 > >> able to reproduce a NAND corruption: > > What does your user to reproduce this? >=20 > Richard, >=20 > It's unclear at the moment. It's one of those 'this happened twice on > two different boards' reports without a lot of detail. However I do > know they do write to the filesystem on every boot and do encounter > random power-cuts. >=20 > >> [ 10.611972] UBIFS (ubi0:2): background thread "ubifs_bgt0_2" starte= d, > >> PID 631 [ 10.634365] ubi0 warning: ubi_io_read: error -74 (ECC error) > >> while reading 253952 bytes from PEB 2807:8192, read only 253952 bytes, > >> retry [ 10.657492] ubi0 warning: ubi_io_read: error -74 (ECC error) > >> while reading 253952 bytes from PEB 2807:8192, read only 253952 bytes, > >> retry [ > >> 10.681137] ubi0 warning: ubi_io_read: error -74 (ECC error) while read= ing > >> 253952 bytes from PEB 2807:8192, read only 253952 bytes, retry [ > >> 10.704267] ubi0 error: ubi_io_read: error -74 (ECC error) while reading > >> 253952 bytes from PEB 2807:8192, read 253952 bytes BTW: I miss a back trace here. How did you obtain that messages? =20 > >> The kernel they are using is a bit out of date but does have > >> 'gpmi-nand: Handle ECC Errors in erased pages' [1] patch > >>=20 > >> I'm wondering if the 'unstable bits issue' [2] is still an issue or if > >> the UBI/UBFS Documentation is out of date and this has been resolved. > >> If it has been resolved, can anyone point me to the patches. > >=20 > > This issue is highly theoretical and I never actually saw it in the wil= d. > > Every single time someone claimed to suffer from that, it turned out to= be > > something else. Currently UBI/UBIFS has no counter measurement, for the > > said reasons. > > This reminds me that we have to update the website... > >=20 > > So did you verify (with your NAND vendor) that this really is the named > > issue? > I have no idea if what the user reported is the unstable bits issue > but the fact you've never seen it occur in the wild tells me probably > not. I'd be surprised, but you never know. :-) Just to be sure, this is SLC NAND, right? > They are using a rather old kernel (4.4 but with a patch to gpmi-nand > backported from 4.7). I will setup a controlled test with random > power-cuts in a test fixture I have to see if I can get it to re-occur > on a) the old kernel and then b) the current kernel. Thanks, //richard