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b=kwVi9cZ5mJDbomvempSuT38rEX96yv1TgwsDLUDunVpi1syrOHg7zwScqRdYGd5kl n5hl2gPdjH6upwxFkyly8dJbNzmTb6fyu3Jt52bHGe6mEZy8tceQJWK8QWN5sJQLMq fZ8FVaysZQ/xKq3oCKA63Bik6teeyJ7ZtayoSlt26LNQl1CWtCLIgfqExBEtZ4XptE j1MjzOA9HFzluoW9QpTKQlus+Eu3UFz9ZJT4rlJnv855B2juyNzkmnJ6LGDsrRYYZk 1TqC/3v8nKn6nYyaSvmYLtCNqy2JokCVn3qEMdMy6G4ZkM2rKEwyS6Q9lvh8KTOazn nHU7iyeHYKUeg== Message-ID: <8bb53d9a-8870-410c-9a41-f8b536ef0780@kernel.org> Date: Tue, 11 Aug 2026 17:14:32 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 3/4] mm/secretmem: zeroize secret pages before kdump To: =?UTF-8?Q?Jan_Sebastian_G=C3=B6tte?= , =?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> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: B8FDAA0015 X-Stat-Signature: 5g953iif5c15czxi7zqebw3qcdncdtbc X-HE-Tag: 1786461278-285132 X-HE-Meta: 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 OkYCLLhS chFx2dWPZmrCNuiVnB6OT1tf7GntkF1ATljTaVqw8lx2p8H9MEsjlAhDSVNeooswuBY7XaxXr/WEZy/e3VYgsUpO2LpF43NBSdZyWxEZ4m5RTLv7KYSJ5blU8Qk4yIx3AmzeJip1qZICIepjdgIiZbsw2xVxvEZ8N0wOslRkgStX7pt7wsBFkTZHIo1jbgHe5cyEyJJDxmVASgFf65L+gqRSmJOM968mxrkJPzDowBErCQY3aav6uTznTs1AvaveIfw8jyCFdk/ajjuR0lfzhfODekg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 8/11/26 17:05, Jan Sebastian Götte wrote: > 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. What I was thinking when I looked at patch #3+#4: 50% of the users you add are irrelevant in practice. Or are you saying that you are going to start using secretmem for your use case? -- Cheers, David