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From: Will Deacon <will@kernel.org>
To: Nick Desaulniers <ndesaulniers@google.com>
Cc: 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>,
	LKML <linux-kernel@vger.kernel.org>,
	Linux Memory Management List <linux-mm@kvack.org>,
	Vinayak Menon <vinmenon@codeaurora.org>,
	"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v4 4/8] mm: Move immutable fields of 'struct vm_fault' into anonymous struct
Date: Thu, 21 Jan 2021 12:48:25 +0000	[thread overview]
Message-ID: <20210121124825.GB22123@willie-the-truck> (raw)
In-Reply-To: <CAKwvOd=UvtSnWiB94gvm0SE9DeJsaaVTJ_fpfh2B4NT1mhr-GQ@mail.gmail.com>

On Wed, Jan 20, 2021 at 10:13:37AM -0800, Nick Desaulniers wrote:
> On Wed, Jan 20, 2021 at 9:36 AM Will Deacon <will@kernel.org> wrote:
> >
> > 'struct vm_fault' contains both information about the fault being
> > serviced alongside mutable fields contributing to the state of the
> > fault-handling logic. Unfortunately, the distinction between the two is
> > not clear-cut, and a number of callers end up manipulating the structure
> > temporarily before restoring it when returning.
> >
> > Try to clean this up by moving the immutable fault information into an
> > anonymous struct, which will later be marked as 'const'. GCC will then
> > complain (with an error) about modification of these fields after they
> > have been initialised, although LLVM currently allows them without even
> > a warning:
> >
> > https://bugs.llvm.org/show_bug.cgi?id=48755
> 
> I think this paragraph+link would be better on patch 8/8.

Agreed, I'll move it.

Will

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  reply	other threads:[~2021-01-21 12:49 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-01-20 17:36 [PATCH v4 0/8] Create 'old' ptes for faultaround mappings on arm64 with hardware access flag Will Deacon
2021-01-20 17:36 ` [PATCH v4 1/8] mm: Cleanup faultaround and finish_fault() codepaths Will Deacon
2021-01-20 17:36 ` [PATCH v4 2/8] mm: Allow architectures to request 'old' entries when prefaulting Will Deacon
2021-01-20 17:36 ` [PATCH v4 3/8] arm64: mm: Implement arch_wants_old_prefaulted_pte() Will Deacon
2021-01-20 17:36 ` [PATCH v4 4/8] mm: Move immutable fields of 'struct vm_fault' into anonymous struct Will Deacon
2021-01-20 18:13   ` Nick Desaulniers
2021-01-21 12:48     ` Will Deacon [this message]
2021-01-20 17:36 ` [PATCH v4 5/8] mm: Pass 'address' to map to do_set_pte() and drop FAULT_FLAG_PREFAULT Will Deacon
2021-01-20 17:36 ` [PATCH v4 6/8] mm: Avoid modifying vmf.address in __collapse_huge_page_swapin() Will Deacon
2021-01-20 17:36 ` [PATCH v4 7/8] mm: Use static initialisers for immutable fields of 'struct vm_fault' Will Deacon
2021-01-20 18:21   ` Nick Desaulniers
2021-01-21 12:50     ` Will Deacon
2021-01-20 17:36 ` [PATCH v4 8/8] mm: Mark anonymous struct field of 'struct vm_fault' as 'const' Will Deacon
2021-01-20 18:27   ` Nick Desaulniers
2021-01-20 19:02     ` Linus Torvalds
2021-01-21 13:11       ` Will Deacon
2021-01-21 19:24         ` Nick Desaulniers
2021-01-21 21:28           ` Will Deacon
2021-01-22 19:10             ` Nick Desaulniers
2021-01-22 19:27               ` Will Deacon
2021-01-22 17:47         ` Linus Torvalds
2021-01-26 23:08 ` [PATCH v4 0/8] Create 'old' ptes for faultaround mappings on arm64 with hardware access flag Will Deacon
2021-01-26 23:28   ` Hugh Dickins
2021-01-27 17:16     ` Will Deacon

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