linux-kernel - Re: [PATCH v4 5/7] mm/x86: arch_check_zapped

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Message-ID: <878qx80xy8.ffs@tglx>
Date: Thu, 08 Aug 2024 00:28:47 +0200
From: Thomas Gleixner <tglx@...utronix.de>
To: Peter Xu <peterx@...hat.com>, linux-kernel@...r.kernel.org,
 linux-mm@...ck.org
Cc: "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>, Michael Ellerman
 <mpe@...erman.id.au>, Oscar Salvador <osalvador@...e.de>, Dan Williams
 <dan.j.williams@...el.com>, James Houghton <jthoughton@...gle.com>,
 Matthew Wilcox <willy@...radead.org>, Nicholas Piggin <npiggin@...il.com>,
 Rik van Riel <riel@...riel.com>, Dave Jiang <dave.jiang@...el.com>, Andrew
 Morton <akpm@...ux-foundation.org>, x86@...nel.org, Ingo Molnar
 <mingo@...hat.com>, Rick P Edgecombe <rick.p.edgecombe@...el.com>, "Kirill
 A . Shutemov" <kirill@...temov.name>, peterx@...hat.com,
 linuxppc-dev@...ts.ozlabs.org, Mel Gorman <mgorman@...hsingularity.net>,
 Hugh Dickins <hughd@...gle.com>, Borislav Petkov <bp@...en8.de>, David
 Hildenbrand <david@...hat.com>, Vlastimil Babka <vbabka@...e.cz>, Dave
 Hansen <dave.hansen@...ux.intel.com>, Christophe Leroy
 <christophe.leroy@...roup.eu>, Huang Ying <ying.huang@...el.com>
Subject: Re: [PATCH v4 5/7] mm/x86: arch_check_zapped_pud()

On Wed, Aug 07 2024 at 15:48, Peter Xu wrote:

> Subject: mm/x86: arch_check_zapped_pud()

Is not a proper subject line. It clearly lacks a verb.

  Subject: mm/x86: Implement arch_check_zapped_pud()

> Introduce arch_check_zapped_pud() to sanity check shadow stack on PUD zaps.
> It has the same logic of the PMD helper.

s/of/as/

> +
> +void arch_check_zapped_pud(struct vm_area_struct *vma, pud_t pud)
> +{
> +	/* See note in arch_check_zapped_pte() */
> +	VM_WARN_ON_ONCE(!(vma->vm_flags & VM_SHADOW_STACK) &&
> +			pud_shstk(pud));

Please get rid of the line break. You have 100 characters.

> +}
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index 2a6a3cccfc36..2289e9f7aa1b 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -447,6 +447,13 @@ static inline void arch_check_zapped_pmd(struct vm_area_struct *vma,
>  }
>  #endif
>  
> +#ifndef arch_check_zapped_pud
> +static inline void arch_check_zapped_pud(struct vm_area_struct *vma,
> +					 pud_t pud)
> +{

Ditto..

> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 0024266dea0a..81c5da0708ed 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c

Why is a mm change burried in a patch which is named mm/x86?

It's clearly documented that core changes with the generic fallback come
in one patch and the architecture override in a separate one afterwards.

Do we write documentation just for the sake of writing it?

Thanks,

        tglx