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From: Nick Desaulniers <ndesaulniers@google.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Will Deacon <will@kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Jan Kara <jack@suse.cz>, Minchan Kim <minchan@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	Vinayak Menon <vinmenon@codeaurora.org>,
	Hugh Dickins <hughd@google.com>,
	Android Kernel Team <kernel-team@android.com>
Subject: Re: [RFC PATCH 4/8] mm: Separate fault info out of 'struct vm_fault'
Date: Tue, 19 Jan 2021 16:00:26 -0800	[thread overview]
Message-ID: <CAKwvOdkwi1huq-xNDKjfw8ooL69E03Ue3LzstG7T-bGX-cM9aA@mail.gmail.com> (raw)
In-Reply-To: <CAHk-=wjWQFSZci+By4wXAEx6EDH4nss7tf5QimQpF53rnHa7Wg@mail.gmail.com>

On Fri, Jan 15, 2021 at 1:33 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Fri, Jan 15, 2021 at 1:23 AM Will Deacon <will@kernel.org> wrote:
> >
> > Hmm. The feedback on the clang bug suggests that GCC is the one in the
> > wrong here (although the argument is based on C11 and I haven't trawled
> > through the standards to see how this has evolved):
>
> Oh well.
>
> That writing is absolutely the _worst_ kind of weaselwording standards
> language reading, trying to make excuses for bad behavior by basically
> depending on "this language is unclear", and trying to say that the
> buggy behavior is required by C11.
>
> What a disappointment.

I don't really understand British humor either, but I assume that's
how the language lawyers throw shade on one anothers' standards.
Richard is both the WG21 spec editor (C++) and British, IIRC.
Apparently, there's a long conversion (behind closed doors; it's the
ISO way) going on in regards to the thread Richard has kicked off with
them (WG14; C).  Moreso on what should happen with the _Atomic
qualifier, assignments, and memcpy.  So it is still an important thing
to nail down the language spec.

Note there were also a lot of discussions lately on "where should the
volatile qualifier be allowed, or not."
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1152r0.html
https://www.youtube.com/watch?v=KJW_DLaVXIY
(2018? ok, maybe not lately.  Lately for C)

I view this similarly as "where should the const qualifier be allowed, or not."
-- 
Thanks,
~Nick Desaulniers

WARNING: multiple messages have this Message-ID

From: Nick Desaulniers <ndesaulniers@google.com>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Android Kernel Team <kernel-team@android.com>,
	Jan Kara <jack@suse.cz>, Minchan Kim <minchan@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Hugh Dickins <hughd@google.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux-MM <linux-mm@kvack.org>,
	Vinayak Menon <vinmenon@codeaurora.org>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Will Deacon <will@kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [RFC PATCH 4/8] mm: Separate fault info out of 'struct vm_fault'
Date: Tue, 19 Jan 2021 16:00:26 -0800	[thread overview]
Message-ID: <CAKwvOdkwi1huq-xNDKjfw8ooL69E03Ue3LzstG7T-bGX-cM9aA@mail.gmail.com> (raw)
In-Reply-To: <CAHk-=wjWQFSZci+By4wXAEx6EDH4nss7tf5QimQpF53rnHa7Wg@mail.gmail.com>

On Fri, Jan 15, 2021 at 1:33 PM Linus Torvalds
<torvalds@linux-foundation.org> wrote:
>
> On Fri, Jan 15, 2021 at 1:23 AM Will Deacon <will@kernel.org> wrote:
> >
> > Hmm. The feedback on the clang bug suggests that GCC is the one in the
> > wrong here (although the argument is based on C11 and I haven't trawled
> > through the standards to see how this has evolved):
>
> Oh well.
>
> That writing is absolutely the _worst_ kind of weaselwording standards
> language reading, trying to make excuses for bad behavior by basically
> depending on "this language is unclear", and trying to say that the
> buggy behavior is required by C11.
>
> What a disappointment.

I don't really understand British humor either, but I assume that's
how the language lawyers throw shade on one anothers' standards.
Richard is both the WG21 spec editor (C++) and British, IIRC.
Apparently, there's a long conversion (behind closed doors; it's the
ISO way) going on in regards to the thread Richard has kicked off with
them (WG14; C).  Moreso on what should happen with the _Atomic
qualifier, assignments, and memcpy.  So it is still an important thing
to nail down the language spec.

Note there were also a lot of discussions lately on "where should the
volatile qualifier be allowed, or not."
http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1152r0.html
https://www.youtube.com/watch?v=KJW_DLaVXIY
(2018? ok, maybe not lately.  Lately for C)

I view this similarly as "where should the const qualifier be allowed, or not."
-- 
Thanks,
~Nick Desaulniers

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2021-01-20  0:07 UTC|newest]

Thread overview: 52+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-14 17:59 [PATCH v3 0/8] Create 'old' ptes for faultaround mappings on arm64 with hardware access flag Will Deacon
2021-01-14 17:59 ` Will Deacon
2021-01-14 17:59 ` [PATCH v3 1/8] mm: Cleanup faultaround and finish_fault() codepaths Will Deacon
2021-01-14 17:59   ` Will Deacon
2021-02-09 20:24   ` Guenter Roeck
2021-02-09 20:24     ` Guenter Roeck
2021-02-10 11:44     ` Will Deacon
2021-02-10 11:44       ` Will Deacon
2021-02-10 14:57       ` Guenter Roeck
2021-02-10 14:57         ` Guenter Roeck
2021-01-14 17:59 ` [PATCH v3 2/8] mm: Allow architectures to request 'old' entries when prefaulting Will Deacon
2021-01-14 17:59   ` Will Deacon
2021-01-14 17:59 ` [PATCH v3 3/8] arm64: mm: Implement arch_wants_old_prefaulted_pte() Will Deacon
2021-01-14 17:59   ` Will Deacon
2021-01-14 17:59 ` [RFC PATCH 4/8] mm: Separate fault info out of 'struct vm_fault' Will Deacon
2021-01-14 18:16   ` Linus Torvalds
2021-01-14 18:16     ` Linus Torvalds
2021-01-14 18:16     ` Linus Torvalds
2021-01-14 19:00     ` Will Deacon
2021-01-14 19:00       ` Will Deacon
2021-01-14 19:09       ` Linus Torvalds
2021-01-14 19:09         ` Linus Torvalds
2021-01-14 19:09         ` Linus Torvalds
2021-01-14 19:41         ` Will Deacon
2021-01-14 19:41           ` Will Deacon
2021-01-14 20:09           ` Nick Desaulniers
2021-01-14 20:09             ` Nick Desaulniers
2021-01-14 20:09             ` Nick Desaulniers
2021-01-14 21:11           ` Linus Torvalds
2021-01-14 21:11             ` Linus Torvalds
2021-01-14 21:11             ` Linus Torvalds
2021-01-15  9:23             ` Will Deacon
2021-01-15  9:23               ` Will Deacon
2021-01-15 21:32               ` Linus Torvalds
2021-01-15 21:32                 ` Linus Torvalds
2021-01-15 21:32                 ` Linus Torvalds
2021-01-20  0:00                 ` Nick Desaulniers [this message]
2021-01-20  0:00                   ` Nick Desaulniers
2021-01-20  0:00                   ` Nick Desaulniers
2021-01-14 17:59 ` [RFC PATCH 5/8] mm: Pass 'address' to map to do_set_pte() and drop FAULT_FLAG_PREFAULT Will Deacon
2021-01-14 17:59   ` Will Deacon
2021-01-14 18:17   ` Linus Torvalds
2021-01-14 18:17     ` Linus Torvalds
2021-01-14 18:17     ` Linus Torvalds
2021-01-15 10:24     ` Will Deacon
2021-01-15 10:24       ` Will Deacon
2021-01-14 17:59 ` [RFC PATCH 6/8] mm: Avoid modifying vmf.info.address in __collapse_huge_page_swapin() Will Deacon
2021-01-14 17:59   ` Will Deacon
2021-01-14 17:59 ` [RFC PATCH 7/8] mm: Use static initialisers for 'info' field of 'struct vm_fault' Will Deacon
2021-01-14 17:59   ` Will Deacon
2021-01-14 17:59 ` [RFC PATCH 8/8] mm: Mark 'info' field of 'struct vm_fault' as 'const' Will Deacon
2021-01-14 17:59   ` Will Deacon

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