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Tue, 11 Aug 2026 11:05:59 -0400 (EDT) Message-ID: Date: Tue, 11 Aug 2026 17:05:58 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 3/4] mm/secretmem: zeroize secret pages before kdump To: "David Hildenbrand (Arm)" , =?UTF-8?Q?Jan_Sebastian_G=C3=B6tte?= Cc: devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, keyrings@vger.kernel.org, linux-mm@kvack.org, linux-security-module@vger.kernel.org, linux-integrity@vger.kernel.org References: <20260731162739.158320-1-linux@jaseg.de> <20260731162739.158320-4-linux@jaseg.de> <70c578dc-769f-465f-a146-4a4695f747c1@kernel.org> Content-Language: en-US From: =?UTF-8?Q?Jan_Sebastian_G=C3=B6tte?= In-Reply-To: <70c578dc-769f-465f-a146-4a4695f747c1@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: qh3nmfgd5az9yan1rgiwp9fbkgkwos6h X-Rspamd-Queue-Id: 95C7240015 X-HE-Tag: 1786460762-742915 X-HE-Meta: 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 dFxojMXU YvyblDADTTxjcJmNZEKU+PwhDSH3qVziwDJr8rDMoaWeXbGfwkf/qDuWVcHkTFSEWDnqQWCvzxHX3JX89Qse7jgqbgd0qtnnNalbPUutMo079PKCl1JUIsD1rKu/Aa0kO4SJ+lQHz6gY/JM0gZIIlQuFRz8CZXGlDRTlq6d9Q9eKagvpvk5Yp4kVWxYt6Izsh3m8tNeJcm7cE6fzvuVUhI880Va2mibdEY2QTcqI+8W4XdMzVQ02fcN0k9kkAPIBNroqQrsSrI/cB0bhjYlVYb66MnOIU56QtF35ZShKIPLHWqjG9sElptZimDKSWjWc7D2sJG8HfjL6ilHvxBH6+8auI4+iFLFnqFGBWxS6223YxcqQKaesTCMY8A6Zghtr2TLvZ Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/11/26 16:53, David Hildenbrand (Arm) wrote: > On 7/31/26 18:27, Jan Sebastian Götte wrote: >> Register a CRASH_ZEROIZE notifier that wipes secretmem folios. As a >> result, when CONFIG_CRASH_ZEROIZE is set, secretmem areas will be >> cleared before the kdump kernel is kexec'ed. > > Are you actually using secretmem in your use case? I heard some rumors that > secretmem isn't used all that much in practice :) I'm aware nobody is really using secretmem. I decided to build this on top of secretmem because it's an existing API that actually kind of fits the use case. While I could have added a new API just for this (marking userspace memory as wipe-on-crash), making it part of secretmem instead gives some additional defense-in-depth protection for both users who only need wiping, and for users who only want secretmem's additional protection against kernel memory read primitives so I think everyone wins here.