Re: [PATCH v15 07/26] x86/mm: Remove _PAGE_DIRTY_HW from kernel RO pages - Yu, Yu-cheng

From: "Yu, Yu-cheng" <yu-cheng.yu@intel.com>
To: Borislav Petkov <bp@alien8.de>
Cc: x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org,
	linux-mm@kvack.org, linux-arch@vger.kernel.org,
	linux-api@vger.kernel.org, Arnd Bergmann <arnd@arndb.de>,
	Andy Lutomirski <luto@kernel.org>,
	Balbir Singh <bsingharora@gmail.com>,
	Cyrill Gorcunov <gorcunov@gmail.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Eugene Syromiatnikov <esyr@redhat.com>,
	Florian Weimer <fweimer@redhat.com>,
	"H.J. Lu" <hjl.tools@gmail.com>, Jann Horn <jannh@google.com>,
	Jonathan Corbet <corbet@lwn.net>,
	Kees Cook <keescook@chromium.org>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Nadav Amit <nadav.amit@gmail.com>,
	Oleg Nesterov <oleg@redhat.com>, Pavel Machek <pavel@ucw.cz>,
	Peter Zijlstra <peterz@infradead.org>,
	Randy Dunlap <rdunlap@infradead.org>,
	"Ravi V. Shankar" <ravi.v.shankar@intel.com>,
	Vedvyas Shanbhogue <vedvyas.shanbhogue@intel.com>,
	Dave Martin <Dave.Martin@arm.com>,
	Weijiang Yang <weijiang.yang@intel.com>,
	Pengfei Xu <pengfei.xu@intel.com>, Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v15 07/26] x86/mm: Remove _PAGE_DIRTY_HW from kernel RO pages
Date: Mon, 7 Dec 2020 09:11:38 -0800	[thread overview]
Message-ID: <b2deed42-1252-62e1-0d82-beafb917d0ad@intel.com> (raw)
In-Reply-To: <20201207163632.GE20489@zn.tnic>

On 12/7/2020 8:36 AM, Borislav Petkov wrote:
> On Tue, Nov 10, 2020 at 08:21:52AM -0800, Yu-cheng Yu wrote:
>> Kernel read-only PTEs are setup as _PAGE_DIRTY_HW.  Since these become
>> shadow stack PTEs, remove the dirty bit.
> 
> This commit message is laconic to say the least. You need to start
> explaining what you're doing because everytime I look at a patch of
> yours, I'm always grepping the SDM and looking forward in the patchset,
> trying to rhyme up what that is all about.
> 
> Like for this one. I had to fast-forward to the next patch where all
> that is explained. But this is not how review works - each patch's
> commit message needs to be understandable on its own because when
> they land upstream, they're not in a patchset like here. And review
> should be done in the order the patches are numbered - not by jumping
> back'n'forth.
> 
> So please think of the readers of your patches when writing those commit
> messages. Latter are *not* write-only and not unimportant.
> 
> And those readers haven't spent copious amounts of time on the
> technology so being more verbose and explaining things is a Good
> Thing(tm). Don't worry about explaining too much - better too much than
> too little.
> 
> And last but not least, having understandable and properly written
> commit messages increases the chances of your patches landing upstream
> considerably.
> 
> Thx.
> 

Thanks for your feedback.  I will improve the commit logs.

--
Yu-cheng