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arc=none smtp.client-ip=217.70.183.195 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="RHLmSF0H" Received: by mail.gandi.net (Postfix) with ESMTPSA id 2A6E31FCEC; Mon, 12 May 2025 15:33:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=gm1; t=1747064009; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=T3nppZjhciBZhLeJLxjh7ZLlfMua9hGZ5VJuDw19EWI=; b=RHLmSF0Hlh9PYHo4GQvjF53CCW0Le14W7MAJlAFMkuUNLSMVTIEW/ny4K4t8bxtKfAFSPP wbl0wMl74ZD2axDk/hndzpa5xNf0n37IxlrupaoukYQjYi/YodYy2F99FS8luuJWUe4xWv uCh2wAD392tr/H8IvRZEaYKXyoElsa2Mhl/gB6hbSEkvaDtVQMYZR9Bh/r3YLsSsX5QUlr 5fe91EcZxdBUCkC5HYHngvtaYMFjrRGq9ell6dVNn2ejgwDlB4+z+Fuk7XJ+ie2Kg/P9U4 1LX4ACBHhy5TynAV28pfiq8ha8/ecx+JD0VwWBCWzecVBCvGkPQccwYk3gi+gA== From: Miquel Raynal To: Richard Weinberger Cc: =?utf-8?B?Q3PDs2vDoXM=?= Bence , linux-mtd , linux-kernel , Vignesh Raghavendra Subject: Re: [PATCH v3] mtd: Verify written data in paranoid mode In-Reply-To: <1689545397.30901605.1747063396608.JavaMail.zimbra@nod.at> (Richard Weinberger's message of "Mon, 12 May 2025 17:23:16 +0200 (CEST)") References: <20250512084033.69718-1-csokas.bence@prolan.hu> <87frhambri.fsf@bootlin.com> <1200504110.30346467.1747054025727.JavaMail.zimbra@nod.at> <4ebe2146-ee1c-4325-8259-be3803475f1f@prolan.hu> <87r00ugcat.fsf@bootlin.com> <1689545397.30901605.1747063396608.JavaMail.zimbra@nod.at> User-Agent: mu4e 1.12.7; emacs 29.4 Date: Mon, 12 May 2025 17:33:28 +0200 Message-ID: <87y0v1g7xz.fsf@bootlin.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-GND-State: clean X-GND-Score: -100 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeefvddrtddtgdeftdduieefucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuifetpfffkfdpucggtfgfnhhsuhgsshgtrhhisggvnecuuegrihhlohhuthemuceftddunecusecvtfgvtghiphhivghnthhsucdlqddutddtmdenucfjughrpefhvfevufgjfhgffffkgggtgfesthhqredttderjeenucfhrhhomhepofhiqhhuvghlucftrgihnhgrlhcuoehmihhquhgvlhdrrhgrhihnrghlsegsohhothhlihhnrdgtohhmqeenucggtffrrghtthgvrhhnpeffgefhjedtfeeigeduudekudejkedtiefhleelueeiueevheekvdeludehiedvfeenucfkphepledtrdekledrudeifedruddvjeenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepihhnvghtpeeltddrkeelrdduieefrdduvdejpdhhvghloheplhhotggrlhhhohhsthdpmhgrihhlfhhrohhmpehmihhquhgvlhdrrhgrhihnrghlsegsohhothhlihhnrdgtohhmpdhnsggprhgtphhtthhopeehpdhrtghpthhtoheprhhitghhrghrugesnhhougdrrghtpdhrtghpthhtoheptghsohhkrghsrdgsvghntggvsehprhholhgrnhdrhhhupdhrtghpthhtoheplhhinhhugidqmhhtugeslhhishhtshdrihhnfhhrrgguvggrugdrohhrghdprhgtphhtthhopehlihhnuhigqdhkvghrnhgvlhesvhhgvghrrdhkvghrnhgvlhdrohhrghdprhgtphhtthhopehvihhgnhgvshhhrhesthhirdgtohhm X-GND-Sasl: miquel.raynal@bootlin.com On 12/05/2025 at 17:23:16 +02, Richard Weinberger wrote: > ----- Urspr=C3=BCngliche Mail ----- >> Von: "Miquel Raynal" >>> The problem we _have_ though happens to be a bit different: here we are >>> blursed with a system that corrupts data at a noticeable >>> probability. But the model is the same: a stochastic process introducing >>> bit errors on write. But I sincerely hope no one else has this problem, >>> and this is *not* the primary aim of this patch; it just happens to >>> solve our issue as well. But I intend it to be useful for the larger >>> Linux community, thus the primary goal is to solve the first issue. >>=20 >> I don't have a strong opinion there but I don't dislike this idea >> because it might also help troubleshooting errors sometimes. It is very >> hard to understand issues which happen to be discovered way after they >> have been generated (typically during a read, way later than a "faulty" >> write). Having this paranoid option would give a more synchronous >> approach which is easier to work with sometimes. > > UBI offers this already, there is a write self-check as part of the io > checks that can be enabled > via debugfs per UBI device. > So for troubleshooting this should be good enough. > There is room for improvement, though. Currently it uses vmalloc(). UBI is full of uncovered resources :-)