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Peter Anvin" , Tony Luck , Andy Lutomirski , Peter Zijlstra , Andrew Morton , Naoya Horiguchi , linux-kernel@vger.kernel.org, linux-edac@vger.kernel.org, linux-mm@kvack.org, Guohanjun Subject: Re: [PATCH -next v4 2/3] x86/mce: rename MCE_IN_KERNEL_COPYIN to MCE_IN_KERNEL_COPY_MC Message-ID: <20240202133911.GBZbzwf-M37M-J3EJX@fat_crate.local> References: <20240111135548.3207437-1-tongtiangen@huawei.com> <20240111135548.3207437-3-tongtiangen@huawei.com> <20240131070258.GGZbnwov0g918F-FGz@fat_crate.local> <3009aadd-69d6-c797-20b4-95cf926b6dd9@huawei.com> <20240201142016.GFZbuooG9CRoK90U2C@fat_crate.local> <39c1e4d2-b1d0-91ae-595e-1add4698dd7f@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <39c1e4d2-b1d0-91ae-595e-1add4698dd7f@huawei.com> X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: B2CDE18001C X-Stat-Signature: p851qsktakkxfi6nsxhdbgf7on9k38r6 X-Rspam-User: X-HE-Tag: 1706881180-921503 X-HE-Meta: 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 FmFLwpeo P0fGDfsjx6LxYE5jVAhEtgB8TzH2hpHsfBUu1GPgYSbTS4nwmGz5JEpl382WiNLPmLqgUzmaQUEBaEGA2LzKFrjrZO21xb4x2Y9FF9JTNmAhK+wlPq7LvCtLkKbv+TOZX+0FM2zR9gbxOAPmop4n7VX14FunnsKJJKsU9dX/ZVT6nUXOF2MKdL3CQcJ/Eja/rCgYv/VqIZh2P8pM8eNkY6oKeOTGgcSDzUigES9iCAaZdqUhED7zJekhTUQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Feb 02, 2024 at 03:51:12PM +0800, Tong Tiangen wrote: > Currently, there are some kernel memory copy scenarios is also mc safe > which use copy_mc_to_kernel() or copy_mc_user_highpage(), these kernel- > to-kernel copy use fixup_type EX_TYPE_DEFAULT_MCE_SAFE. In these > scenarios, posion pages need to be isolated too and the current So you have, for example: unsigned long __must_check copy_mc_to_kernel(void *dst, const void *src, unsigned len) Now imagine you get a MCE for *dst which is some kernel page which cannot be poisoned: direct map, kernel text, and so on. Attempting to poison such a page would not work, to put it mildly. So, again, what *exactly* are you "fixing" here? When I read "Currently, there are some kernel memory copy scenarios" and there's nothing more explaining what those scenarios are, I'm tempted to ignore this completely until you give a detailed and concrete example what the problem is: What exactly are you doing, what goes wrong, why does this need to be fixed and so on... If there isn't such a real-life use case you're encountering, then this all is waste of time. Thx. -- Regards/Gruss, Boris. https://people.kernel.org/tglx/notes-about-netiquette