linux-kernel - Re: [PATCH] metag: Drop show_mem() from mem

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Message-ID: <20160805123251.GT2799@techsingularity.net>
Date:	Fri, 5 Aug 2016 13:32:51 +0100
From:	Mel Gorman <mgorman@...hsingularity.net>
To:	James Hogan <james.hogan@...tec.com>
Cc:	linux-metag@...r.kernel.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] metag: Drop show_mem() from mem_init()

On Fri, Aug 05, 2016 at 01:17:04PM +0100, James Hogan wrote:
> The recent commit 599d0c954f91 ("mm, vmscan: move LRU lists to node"),
> changed memory management code so that show_mem() is no longer safe to
> call prior to setup_per_cpu_pageset(), as pgdat->per_cpu_nodestats will
> still be NULL. This causes an oops on metag due to the call to
> show_mem() from mem_init():
> 
>   node_page_state_snapshot(...) + 0x48
>   pgdat_reclaimable(struct pglist_data * pgdat = 0x402517a0)
>   show_free_areas(unsigned int filter = 0) + 0x2cc
>   show_mem(unsigned int filter = 0) + 0x18
>   mem_init()
>   mm_init()
>   start_kernel() + 0x204
> 
> This wasn't a problem before with zone_reclaimable() as zone_pcp_init()
> was already setting zone->pageset to &boot_pageset, via setup_arch() and
> paging_init(), which happens before mm_init():
> 
>   zone_pcp_init(...)
>   free_area_init_core(...) + 0x138
>   free_area_init_node(int nid = 0, ...) + 0x1a0
>   free_area_init_nodes(...) + 0x440
>   paging_init(unsigned long mem_end = 0x4fe00000) + 0x378
>   setup_arch(char ** cmdline_p = 0x4024e038) + 0x2b8
>   start_kernel() + 0x54
> 
> No other arches appear to call show_mem() during boot, and it doesn't
> really add much value to the log, so lets just drop it from mem_init().
> 
> Signed-off-by: James Hogan <james.hogan@...tec.com>
> Cc: Mel Gorman <mgorman@...hsingularity.net>

Acked-by: Mel Gorman <mgorman@...hsingularity.net>

-- 
Mel Gorman
SUSE Labs