linux-kernel - Re: [PATCH] delete unnecessary bootmem struct page array

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Message-ID: <538B314B.2050604@nod.at>
Date:	Sun, 01 Jun 2014 15:57:31 +0200
From:	Richard Weinberger <richard@....at>
To:	Real Name <enjoymindful@...il.com>,
	user-mode-linux-devel@...ts.sourceforge.net
CC:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] delete unnecessary bootmem struct page array

Am 01.06.2014 15:08, schrieb Real Name:
> From: Honggang Li <enjoymindful@...il.com>
> 
> 1) uml kernel bootmem managed through bootmem_data->node_bootmem_map,
> not the struct page array, so the array is unnecessary.
> 
> 2) the bootmem struct page array has been pointed by a *local* pointer,
> struct page *map, in init_maps function. The array can be accessed only
> in init_maps's scope. As a result, uml kernel wastes about 1% of total
> memory.

I reread your patch again.
You missed one important point. init_maps() setups max_mapnr which is used by
virt_addr_valid().

We have to be extremely careful here to not introduce a subtle fuckup.

Thanks,
//richard
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