Re: [PATCH v3 0/4] optimize memory hotplug

From: Pavel Tatashin <pasha.tatashin@oracle.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Steve Sistare <steven.sistare@oracle.com>,
	Daniel Jordan <daniel.m.jordan@oracle.com>,
	Mel Gorman <mgorman@techsingularity.net>,
	Michal Hocko <mhocko@suse.com>,
	Linux Memory Management List <linux-mm@kvack.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	Bharata B Rao <bharata@linux.vnet.ibm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	mingo@redhat.com, hpa@zytor.com, x86@kernel.org,
	dan.j.williams@intel.com, kirill.shutemov@linux.intel.com,
	bhe@redhat.com
Subject: Re: [PATCH v3 0/4] optimize memory hotplug
Date: Wed, 14 Feb 2018 09:14:17 -0500	[thread overview]
Message-ID: <CAOAebxsAXC8CgoRdeD4=1ePwoB6TeqprZgnkenU-aCeKGv_p+w@mail.gmail.com> (raw)
In-Reply-To: <20180214080930.n44x3arzqanja5zq@gmail.com>

Hi Ingo,

Thank you very much for your review. I will address spelling issues,
and will also try to split the patch #4.  Regarding runtime concern
for patch #3: the extra checking is only performed when the both of
the following CONFIGs are enabled:

CONFIG_DEBUG_VM=y
CONFIG_DEBUG_VM_PGFLAGS=y

I do not expect either of these to be ever enabled on a production systems.

Thank you,
Pavel

On Wed, Feb 14, 2018 at 3:09 AM, Ingo Molnar <mingo@kernel.org> wrote:
>
> * Andrew Morton <akpm@linux-foundation.org> wrote:
>
>> On Tue, 13 Feb 2018 14:31:55 -0500 Pavel Tatashin <pasha.tatashin@oracle.com> wrote:
>>
>> > This patchset:
>> > - Improves hotplug performance by eliminating a number of
>> > struct page traverses during memory hotplug.
>> >
>> > - Fixes some issues with hotplugging, where boundaries
>> > were not properly checked. And on x86 block size was not properly aligned
>> > with end of memory
>> >
>> > - Also, potentially improves boot performance by eliminating condition from
>> >   __init_single_page().
>> >
>> > - Adds robustness by verifying that that struct pages are correctly
>> >   poisoned when flags are accessed.
>>
>> I'm now attempting to get a 100% review rate on MM patches, which is
>> why I started adding my Reviewed-by: when I do that thing.
>>
>> I'm not familiar enough with this code to add my own Reviewed-by:, and
>> we'll need to figure out what to do in such cases.  I shall be sending
>> out periodic review-status summaries.
>>
>> If you're able to identify a suitable reviewer for this work and to
>> offer them beer, that would help.  Let's see what happens as the weeks
>> unfold.
>
> The largest patch, fix patch #2, looks good to me and fixes a real bug.
> Patch #1 and #3 also look good to me (assuming the runtime overhead
> added by patch #3 is OK to you):
>
>   Reviewed-by: Ingo Molnar <mingo@kernel.org>
>
> (I suspect patch #1 and patch #2 should also get a Cc: stable.)
>
> Patch #4 is too large to review IMO: it should be split up into as many patches as
> practically possible. That will also help bisectability, should anything break.
>
> Before applying these patches please fix changelog and code comment spelling.
>
> But it's all good stuff AFAICS!
>
> Thanks,
>
>         Ingo
>
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