linux-kernel - Re: [PATCH V2 2/7] x86/mm: Drop page table entry address output from pxd

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Message-ID: <5af75d55-f65d-4c3d-be85-402386ece04d@redhat.com>
Date: Tue, 17 Sep 2024 13:31:37 +0200
From: David Hildenbrand <david@...hat.com>
To: Dave Hansen <dave.hansen@...el.com>,
 Anshuman Khandual <anshuman.khandual@....com>, linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
 Ryan Roberts <ryan.roberts@....com>, "Mike Rapoport (IBM)"
 <rppt@...nel.org>, Arnd Bergmann <arnd@...db.de>, x86@...nel.org,
 linux-m68k@...ts.linux-m68k.org, linux-fsdevel@...r.kernel.org,
 kasan-dev@...glegroups.com, linux-kernel@...r.kernel.org,
 linux-perf-users@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
 Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
 Dave Hansen <dave.hansen@...ux.intel.com>
Subject: Re: [PATCH V2 2/7] x86/mm: Drop page table entry address output from
 pxd_ERROR()

On 17.09.24 13:19, Dave Hansen wrote:
> On 9/17/24 03:22, David Hildenbrand wrote:
>> Not a big fan of all these "bad PTE" thingies ...
> 
> In general?

In general, after I learned that pmd_bad() fires on perfectly fine 
pmd_large() entries, which makes things like pmd_none_or_clear_bad() 
absolutely dangerous to use in code where we could have THPs ...

Consequently, we stopped using them in THP code, so what's the whole 
point of having them ...

> 
> Or not a big fan of the fact that every architecture has their own
> (mostly) copied-and-pasted set?

Well, that most certainly as well :)

-- 
Cheers,

David / dhildenb