linux-kernel - Re: [EXT] Re: [PATCH v2 0/2] Optimize secure erase performance for certain Kingston eMMC devices

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Message-ID: <aUE4xSnW1bHyRRoR@infradead.org>
Date: Tue, 16 Dec 2025 02:47:33 -0800
From: Christoph Hellwig <hch@...radead.org>
To: Luke Wang <ziniu.wang_1@....com>
Cc: Ulf Hansson <ulf.hansson@...aro.org>,
	"axboe@...nel.dk" <axboe@...nel.dk>,
	"linux-block@...r.kernel.org" <linux-block@...r.kernel.org>,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"imx@...ts.linux.dev" <imx@...ts.linux.dev>
Subject: Re: [EXT] Re: [PATCH v2 0/2] Optimize secure erase performance for
 certain Kingston eMMC devices

On Tue, Dec 16, 2025 at 10:02:49AM +0000, Luke Wang wrote:
> In fact, secure erase does not guarantee that data is physically
> erased.

It can't.  Given how Flash storage works there is no way to actually
securely erase data on a per-LBA range basis. 

> And the eMMC 5.1 Spec:
> "NOTE Secure Erase is included for backwards compatibility. New system level implementations
> (based on v4.51 devices and beyond) should use Erase combined with Sanitize instead of secure erase."

And this is 100% correct.  Only a device-level Sanitize operation
can do meaningful erasure of data on Flash based media (or modern
HDDs with all the remapping they do for that matter).