From: Will Deacon <will@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>,
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: Fri, 15 Jan 2021 09:23:13 +0000 [thread overview]
Message-ID: <20210115092313.GA13700@willie-the-truck> (raw)
In-Reply-To: <CAHk-=wixswKjAPt0eEVSHqOQB9tBuO5FeqfyKyxFWyBLEG6EcQ@mail.gmail.com>
On Thu, Jan 14, 2021 at 01:11:12PM -0800, Linus Torvalds wrote:
> On Thu, Jan 14, 2021 at 11:41 AM Will Deacon <will@kernel.org> wrote:
> >
> > Sure enough, an arm64 defconfig builds perfectly alright with that change,
> > but it really shouldn't. I'm using clang 11.0.5, so I had another go with
> > GCC 9.2.1 and bang:
>
> Ok, looks like a clang bug, but a reasonably benign one.
>
> As long as we have sufficient coverage with gcc, we'll get error
> reporting in a timely manner for any new incorrect assignments, so I
> think we can do that constant anonymous struct even if it does mean
> that clang might let some bad cases through (I personally use gcc for
> build testing, and then clang for building my boot kernels, so I'd
> catch anything x86-64 allmodconfig in my build tests).
>
> And keeping it unnamed it would avoid a lot of noisy churn..
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):
https://bugs.llvm.org/show_bug.cgi?id=48755#c1
There is at least some sympathy to generating a warning, so that might
be good enough. Otherwise, I suppose we can explicitly mark the fields
as 'const' but I won't jump to that immediately.
Will
next prev parent reply other threads:[~2021-01-15 9:24 UTC|newest]
Thread overview: 23+ 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 ` [PATCH v3 1/8] mm: Cleanup faultaround and finish_fault() codepaths Will Deacon
2021-02-09 20:24 ` Guenter Roeck
2021-02-10 11:44 ` Will Deacon
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 ` [PATCH v3 3/8] arm64: mm: Implement arch_wants_old_prefaulted_pte() 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 19:00 ` Will Deacon
2021-01-14 19:09 ` Linus Torvalds
2021-01-14 19:41 ` Will Deacon
2021-01-14 20:09 ` Nick Desaulniers
2021-01-14 21:11 ` Linus Torvalds
2021-01-15 9:23 ` Will Deacon [this message]
2021-01-15 21:32 ` Linus Torvalds
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 18:17 ` Linus Torvalds
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 ` [RFC PATCH 7/8] mm: Use static initialisers for 'info' field of 'struct vm_fault' Will Deacon
2021-01-14 17:59 ` [RFC PATCH 8/8] mm: Mark 'info' field of 'struct vm_fault' as 'const' Will Deacon
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