Re: [PATCH v3 13/37] mm: Move VM_UFFD_MINOR_BIT from 37 to 38 (Linux Arch)

Re: [PATCH v3 13/37] mm: Move VM_UFFD_MINOR_BIT from 37 to 38

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To: "peterz@xxxxxxxxxxxxx" <peterz@xxxxxxxxxxxxx>

Subject: Re: [PATCH v3 13/37] mm: Move VM_UFFD_MINOR_BIT from 37 to 38

From: "Edgecombe, Rick P" <rick.p.edgecombe@xxxxxxxxx>

Date: Tue, 15 Nov 2022 17:18:46 +0000

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Cc: "bsingharora@xxxxxxxxx" <bsingharora@xxxxxxxxx>, "hpa@xxxxxxxxx" <hpa@xxxxxxxxx>, "Syromiatnikov, Eugene" <esyr@xxxxxxxxxx>, "rdunlap@xxxxxxxxxxxxx" <rdunlap@xxxxxxxxxxxxx>, "keescook@xxxxxxxxxxxx" <keescook@xxxxxxxxxxxx>, "Yu, Yu-cheng" <yu-cheng.yu@xxxxxxxxx>, "dave.hansen@xxxxxxxxxxxxxxx" <dave.hansen@xxxxxxxxxxxxxxx>, "kirill.shutemov@xxxxxxxxxxxxxxx" <kirill.shutemov@xxxxxxxxxxxxxxx>, "Eranian, Stephane" <eranian@xxxxxxxxxx>, "linux-mm@xxxxxxxxx" <linux-mm@xxxxxxxxx>, "fweimer@xxxxxxxxxx" <fweimer@xxxxxxxxxx>, "nadav.amit@xxxxxxxxx" <nadav.amit@xxxxxxxxx>, "jannh@xxxxxxxxxx" <jannh@xxxxxxxxxx>, "dethoma@xxxxxxxxxxxxx" <dethoma@xxxxxxxxxxxxx>, "kcc@xxxxxxxxxx" <kcc@xxxxxxxxxx>, "linux-arch@xxxxxxxxxxxxxxx" <linux-arch@xxxxxxxxxxxxxxx>, "bp@xxxxxxxxx" <bp@xxxxxxxxx>, "oleg@xxxxxxxxxx" <oleg@xxxxxxxxxx>, "hjl.tools@xxxxxxxxx" <hjl.tools@xxxxxxxxx>, "Yang, Weijiang" <weijiang.yang@xxxxxxxxx>, "Lutomirski, Andy" <luto@xxxxxxxxxx>, "pavel@xxxxxx" <pavel@xxxxxx>, "arnd@xxxxxxxx" <arnd@xxxxxxxx>, "tglx@xxxxxxxxxxxxx" <tglx@xxxxxxxxxxxxx>, "mike.kravetz@xxxxxxxxxx" <mike.kravetz@xxxxxxxxxx>, "x86@xxxxxxxxxx" <x86@xxxxxxxxxx>, "linux-doc@xxxxxxxxxxxxxxx" <linux-doc@xxxxxxxxxxxxxxx>, "jamorris@xxxxxxxxxxxxxxxxxxx" <jamorris@xxxxxxxxxxxxxxxxxxx>, "john.allen@xxxxxxx" <john.allen@xxxxxxx>, "rppt@xxxxxxxxxx" <rppt@xxxxxxxxxx>, "mingo@xxxxxxxxxx" <mingo@xxxxxxxxxx>, "Shankar, Ravi V" <ravi.v.shankar@xxxxxxxxx>, "corbet@xxxxxxx" <corbet@xxxxxxx>, "linux-kernel@xxxxxxxxxxxxxxx" <linux-kernel@xxxxxxxxxxxxxxx>, "linux-api@xxxxxxxxxxxxxxx" <linux-api@xxxxxxxxxxxxxxx>, "gorcunov@xxxxxxxxx" <gorcunov@xxxxxxxxx>, "akpm@xxxxxxxxxxxxxxxxxxxx" <akpm@xxxxxxxxxxxxxxxxxxxx>, "peterx@xxxxxxxxxx" <peterx@xxxxxxxxxx>

In-reply-to: <Y3N14v0ddj/vVV+H@hirez.programming.kicks-ass.net>

References: <20221104223604.29615-1-rick.p.edgecombe@intel.com> <20221104223604.29615-14-rick.p.edgecombe@intel.com> <Y3N14v0ddj/vVV+H@hirez.programming.kicks-ass.net>

Thread-index: AQHY8J5SndDp1MUAmEerJGA0DRW+z64/5ysAgABkOwA=

Thread-topic: [PATCH v3 13/37] mm: Move VM_UFFD_MINOR_BIT from 37 to 38

On Tue, 2022-11-15 at 12:20 +0100, Peter Zijlstra wrote:
> On Fri, Nov 04, 2022 at 03:35:40PM -0700, Rick Edgecombe wrote:
> > From: Yu-cheng Yu <yu-cheng.yu@xxxxxxxxx>
> > 
> > To introduce VM_SHADOW_STACK as VM_HIGH_ARCH_BIT (37), and make all
> > VM_HIGH_ARCH_BITs stay together, move VM_UFFD_MINOR_BIT from 37 to
> > 38.
> 
> Why thought ?!? Changelog utterly fails to provide rationale.

I can beef this up. It is just a cleanup type thing to make things less
scattered around.

Thanks.