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Date: Wed, 1 Nov 2017 22:11:37 +0100 (CET) From: Thomas Gleixner <tglx@...utronix.de> To: Dave Hansen <dave.hansen@...ux.intel.com> cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org, moritz.lipp@...k.tugraz.at, daniel.gruss@...k.tugraz.at, michael.schwarz@...k.tugraz.at, luto@...nel.org, torvalds@...ux-foundation.org, keescook@...gle.com, hughd@...gle.com, x86@...nel.org Subject: Re: [PATCH 02/23] x86, kaiser: do not set _PAGE_USER for init_mm page tables On Tue, 31 Oct 2017, Dave Hansen wrote: > > init_mm is for kernel-exclusive use. If someone is allocating page > tables in it, do not set _PAGE_USER on them. This ensures that > we do *not* set NX on these page tables in the KAISER code. This changelog is confusing at best. Why is this a kaiser issue? Nothing should ever create _PAGE_USER entries in init_mm, right? So this is a general improvement and creating a _PAGE_USER entry in init_mm should be considered a bug in the first place. > +/* > + * _KERNPG_TABLE has _PAGE_USER clear which tells the KAISER code > + * that this mapping is for kernel use only. That makes sure that > + * we leave the mapping usable by the kernel and do not try to > + * sabotage it by doing stuff like setting _PAGE_NX on it. So this comment should not mention KAISER at all. As I explained above there are no user mappings in init_mm and this should be expressed here. The fact that KAISER can make use of this information is a different story. Other than that: Reviewed-by: Thomas Gleixner <tglx@...utronix.de> Thanks, tglx
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