Re: [PATCH v3 09/10] PM / Hibernate: Publish pages restored in-place to arch code

From: James Morse <james.morse@arm.com>
To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Pavel Machek <pavel@ucw.cz>, Will Deacon <will.deacon@arm.com>,
	Sudeep Holla <sudeep.holla@arm.com>,
	Kevin Kang <kkang@intrinsyc.com>,
	Geoff Levand <geoff@infradead.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Mark Rutland <mark.rutland@arm.com>,
	AKASHI Takahiro <takahiro.akashi@linaro.org>,
	wangfei <w.f@huawei.com>, Marc Zyngier <marc.zyngier@arm.com>
Subject: Re: [PATCH v3 09/10] PM / Hibernate: Publish pages restored in-place to arch code
Date: Fri, 04 Dec 2015 16:26:41 +0000	[thread overview]
Message-ID: <5661BEC1.5040400@arm.com> (raw)
In-Reply-To: <20151203120925.GA2220@red-moon>

Hi Lorenzo,

On 03/12/15 12:09, Lorenzo Pieralisi wrote:
> On Thu, Nov 26, 2015 at 05:32:47PM +0000, James Morse wrote:
>> @@ -2427,25 +2434,31 @@ static void *get_buffer(struct memory_bitmap *bm, struct chain_allocator *ca)
>>  	if (PageHighMem(page))
>>  		return get_highmem_page_buffer(page, ca);
> 
> I know it is not a problem for arm64, but you should export the
> "restored" highmem pages list too because arch code may need to use
> it for the same reasons this patch was implemented.

I'm not sure it can be for the same reasons:
kernel/power/snapshot.c:swap_two_pages_data() does the copy for highmem
pages, and then kunmap-s them... if the page is to be used for
execution, it needs to be re-mapped first, possibly at a different address.
The place to do cache maintenance is in the kunmap/kmap calls.

Thanks,

James