linux-kernel - Re: [PATCH 5/5] ACPI / memhotplug: Drop unnecessary code

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Message-ID: <1369079733.5673.58.camel@misato.fc.hp.com>
Date:	Mon, 20 May 2013 13:55:33 -0600
From:	Toshi Kani <toshi.kani@...com>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Wen Congyang <wency@...fujitsu.com>,
	Tang Chen <tangchen@...fujitsu.com>,
	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jiang Liu <liuj97@...il.com>,
	Vasilis Liaskovitis <vasilis.liaskovitis@...fitbricks.com>,
	linux-mm@...ck.org
Subject: Re: [PATCH 5/5] ACPI / memhotplug: Drop unnecessary code

On Mon, 2013-05-20 at 21:47 +0200, Rafael J. Wysocki wrote:
> On Monday, May 20, 2013 11:27:56 AM Toshi Kani wrote:
> > On Sun, 2013-05-19 at 01:34 +0200, Rafael J. Wysocki wrote:
> > > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

 :

> > > -	lock_memory_hotplug();
> > > -
> > > -	/*
> > > -	 * we have offlined all memory blocks like this:
> > > -	 *   1. lock memory hotplug
> > > -	 *   2. offline a memory block
> > > -	 *   3. unlock memory hotplug
> > > -	 *
> > > -	 * repeat step1-3 to offline the memory block. All memory blocks
> > > -	 * must be offlined before removing memory. But we don't hold the
> > > -	 * lock in the whole operation. So we should check whether all
> > > -	 * memory blocks are offlined.
> > > -	 */
> > > -
> > > -	ret = walk_memory_range(start_pfn, end_pfn, NULL,
> > > -				is_memblock_offlined_cb);
> > > -	if (ret) {
> > > -		unlock_memory_hotplug();
> > > -		return ret;
> > > -	}
> > > -
> > 
> > I think the above procedure is still useful for safe guard.
> 
> But then it shoud to BUG_ON() instead of returning an error (which isn't very
> useful for anything now).

Right since we cannot fail at that state.

> > > -	/* remove memmap entry */
> > > -	firmware_map_remove(start, start + size, "System RAM");
> > > -
> > > -	arch_remove_memory(start, size);
> > > -
> > > -	try_offline_node(nid);
> > 
> > The above procedure performs memory hot-delete specific operations and
> > is necessary.
> 
> OK, I see.  I'll replace this patch with something simpler, then.

Thanks.

> What about the other patches in the series?

I will send you my comments later (a bit interrupted for other thing
now).  

-Toshi


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