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Date: Wed, 25 Mar 2015 10:01:44 +0900
From: Gioh Kim <gioh.kim@lge.com>
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To: Roman Pen <r.peniaev@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>,
        Eric Dumazet <edumazet@google.com>,
        David Rientjes <rientjes@google.com>, WANG Chao <chaowang@redhat.com>,
        Fabian Frederick <fabf@skynet.be>, Christoph Lameter <cl@linux.com>,
        Rob Jones <rob.jones@codethink.co.uk>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [RFC v2 1/3] mm/vmalloc: fix possible exhaustion of vmalloc space
 caused by vm_map_ram allocator
References: <1426773881-5757-1-git-send-email-r.peniaev@gmail.com> <1426773881-5757-2-git-send-email-r.peniaev@gmail.com>
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> 
> In current patch I simply put newly allocated block to the tail of a free list,
> thus reduce fragmentation, giving a chance to resolve allocation request using
> older blocks with possible holes left.

It's great.
I think this might be helpful for fragmentation by mix of long-time, short-time mappings.
I do thank you for your work.

> 
> Signed-off-by: Roman Pen <r.peniaev@gmail.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Eric Dumazet <edumazet@google.com>
> Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: David Rientjes <rientjes@google.com>
> Cc: WANG Chao <chaowang@redhat.com>
> Cc: Fabian Frederick <fabf@skynet.be>
> Cc: Christoph Lameter <cl@linux.com>
> Cc: Gioh Kim <gioh.kim@lge.com>
> Cc: Rob Jones <rob.jones@codethink.co.uk>
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org
> Cc: stable@vger.kernel.org
> ---
>   mm/vmalloc.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 39c3388..db6bffb 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -837,7 +837,7 @@ static struct vmap_block *new_vmap_block(gfp_t gfp_mask)
>   
>   	vbq = &get_cpu_var(vmap_block_queue);
>   	spin_lock(&vbq->lock);
> -	list_add_rcu(&vb->free_list, &vbq->free);
> +	list_add_tail_rcu(&vb->free_list, &vbq->free);
>   	spin_unlock(&vbq->lock);
>   	put_cpu_var(vmap_block_queue);
>   
>