From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752351AbcGRWhb (ORCPT ); Mon, 18 Jul 2016 18:37:31 -0400 Received: from host.buserror.net ([209.198.135.123]:58577 "EHLO host.buserror.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751493AbcGRWha (ORCPT ); Mon, 18 Jul 2016 18:37:30 -0400 Message-ID: <1468881442.25630.8.camel@buserror.net> From: Scott Wood To: Boris Brezillon , Hector Palacios Cc: linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org, richard@nod.at, stable@vger.kernel.org, Brian Norris Date: Mon, 18 Jul 2016 17:37:22 -0500 In-Reply-To: <20160718110432.003b52ea@bbrezillon> References: <1468831158-6172-1-git-send-email-hector.palacios@digi.com> <20160718110432.003b52ea@bbrezillon> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.18.5.2-0ubuntu3 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit X-SA-Exim-Connect-IP: 75.72.173.242 X-SA-Exim-Mail-From: oss@buserror.net X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * -15 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] Subject: Re: [PATCH] mtd: nand: fix bug writing 1 byte less than page size X-SA-Exim-Version: 4.2.1 (built Mon, 26 Dec 2011 16:57:07 +0000) X-SA-Exim-Scanned: Yes (on host.buserror.net) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2016-07-18 at 11:04 +0200, Boris Brezillon wrote: > On Mon, 18 Jul 2016 10:39:18 +0200 > Hector Palacios wrote: > > > > > nand_do_write_ops() determines if it is writing a partial page with the > > formula: > > part_pagewr = (column || writelen < (mtd->writesize - 1)) > > > > When 'writelen' is exactly 1 byte less than the NAND page size the formula > > equates to zero, so the code doesn't process it as a partial write, > > although it should. > > As a consequence the function remains in the while(1) loop with 'writelen' > > becoming 0xffffffff and iterating endlessly. > > > > The bug may not be easy to reproduce in Linux since user space tools > > usually force the padding or round-up the write size to a page-size > > multiple. > > This was discovered in U-Boot where the issue can be reproduced by > > writing any size that is 1 byte less than a page-size multiple. > > For example, on a NAND with 2K page (0x800): > > => nand erase.part > > => nand write $loadaddr 7ff   > > > > Signed-off-by: Hector Palacios > Acked-by: Boris Brezillon > > Brian, can you take this patch in your tree. > > As usual, I'm unsure whether we should Cc stable or not, but we > should at least add > > Fixes: 66507c7bc8895 ("mtd: nand: Add support to use nand_base poi databuf > as bounce buffer") That commit just moved the bad test; it was introduced in 29072b96078ffde3 ("[MTD] NAND: add subpage write support"). -Scott