linux-kernel - Re: [PATCH v3 2/4] mm/memory_hotplug: Drop mem_blk check from unregister_mem_sect_under

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Message-ID: <20180816175325.xd4qmlauh65qszsk@xakep.localdomain>
Date:   Thu, 16 Aug 2018 17:53:25 +0000
From:   Pasha Tatashin <Pavel.Tatashin@...rosoft.com>
To:     Oscar Salvador <osalvador@...hadventures.net>
CC:     "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "mhocko@...e.com" <mhocko@...e.com>,
        "vbabka@...e.cz" <vbabka@...e.cz>,
        "dan.j.williams@...el.com" <dan.j.williams@...el.com>,
        "yasu.isimatu@...il.com" <yasu.isimatu@...il.com>,
        "jonathan.cameron@...wei.com" <jonathan.cameron@...wei.com>,
        "david@...hat.com" <david@...hat.com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Oscar Salvador <osalvador@...e.de>
Subject: Re: [PATCH v3 2/4] mm/memory_hotplug: Drop mem_blk check from
 unregister_mem_sect_under_nodes

On 18-08-15 16:42:17, Oscar Salvador wrote:
> From: Oscar Salvador <osalvador@...e.de>
> 
> Before calling to unregister_mem_sect_under_nodes(),
> remove_memory_section() already checks if we got a valid memory_block.
> 
> No need to check that again in unregister_mem_sect_under_nodes().
> 
> If more functions start using unregister_mem_sect_under_nodes() in the
> future, we can always place a WARN_ON to catch null mem_blk's so we can
> safely back off.
> 
> For now, let us keep the check in remove_memory_section() since it is the
> only function that uses it.
> 
> Signed-off-by: Oscar Salvador <osalvador@...e.de>
> Reviewed-by: Andrew Morton <akpm@...ux-foundation.org>

Reviewed-by: Pavel Tatashin <pavel.tatashin@...rosoft.com>

> ---
>  drivers/base/node.c | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/drivers/base/node.c b/drivers/base/node.c
> index 1ac4c36e13bb..dd3bdab230b2 100644
> --- a/drivers/base/node.c
> +++ b/drivers/base/node.c
> @@ -455,10 +455,6 @@ int unregister_mem_sect_under_nodes(struct memory_block *mem_blk,
>  	NODEMASK_ALLOC(nodemask_t, unlinked_nodes, GFP_KERNEL);
>  	unsigned long pfn, sect_start_pfn, sect_end_pfn;
>  
> -	if (!mem_blk) {
> -		NODEMASK_FREE(unlinked_nodes);
> -		return -EFAULT;
> -	}
>  	if (!unlinked_nodes)
>  		return -ENOMEM;
>  	nodes_clear(*unlinked_nodes);
> -- 
> 2.13.6
>