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Date:   Wed, 3 Apr 2019 10:45:12 +0200
From:   Oscar Salvador <osalvador@suse.de>
To:     Anshuman Khandual <anshuman.khandual@arm.com>
Cc:     linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        linux-mm@kvack.org, akpm@linux-foundation.org, will.deacon@arm.com,
        catalin.marinas@arm.com, mhocko@suse.com,
        mgorman@techsingularity.net, james.morse@arm.com,
        mark.rutland@arm.com, robin.murphy@arm.com, cpandya@codeaurora.org,
        arunks@codeaurora.org, dan.j.williams@intel.com,
        logang@deltatee.com, pasha.tatashin@oracle.com, david@redhat.com,
        cai@lca.pw
Subject: Re: [PATCH 4/6] mm/hotplug: Reorder arch_remove_memory() call in
 __remove_memory()
Message-ID: <20190403084512.otsvifwxuycoe5dn@d104.suse.de>
References: <1554265806-11501-1-git-send-email-anshuman.khandual@arm.com>
 <1554265806-11501-5-git-send-email-anshuman.khandual@arm.com>
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On Wed, Apr 03, 2019 at 10:00:04AM +0530, Anshuman Khandual wrote:
> Re-ordering arch_remove_memory() with memblock_[free|remove] solves the
> problem on arm64 as pfn_valid() behaves correctly and returns positive
> as memblock for the address range still exists. arch_remove_memory()
> removes applicable memory sections from zone with __remove_pages() and
> tears down kernel linear mapping. Removing memblock regions afterwards
> is consistent.
> 
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>

Yes, I cannot see a way of those two colliding with each other, and
a testing on my box did not raise anything spooky either.

Reviewed-by: Oscar Salvador <osalvador@suse.de>

> ---
>  mm/memory_hotplug.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 0082d69..71d0d79 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1872,11 +1872,10 @@ void __ref __remove_memory(int nid, u64 start, u64 size)
>  
>  	/* remove memmap entry */
>  	firmware_map_remove(start, start + size, "System RAM");
> +	arch_remove_memory(nid, start, size, NULL);
>  	memblock_free(start, size);
>  	memblock_remove(start, size);
>  
> -	arch_remove_memory(nid, start, size, NULL);
> -
>  	try_offline_node(nid);
>  
>  	mem_hotplug_done();
> -- 
> 2.7.4
> 

-- 
Oscar Salvador
SUSE L3