linux-kernel - Re: [PATCH] mm/balloon_compaction: suppress allocation warnings

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Message-ID: <ba01ec8c-19c3-847c-a315-2f70f4b1fe31@redhat.com>
Date:   Wed, 21 Aug 2019 18:05:54 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Nadav Amit <namit@...are.com>,
        "Michael S. Tsirkin" <mst@...hat.com>
Cc:     Jason Wang <jasowang@...hat.com>,
        virtualization@...ts.linux-foundation.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm/balloon_compaction: suppress allocation warnings

On 20.08.19 11:16, Nadav Amit wrote:
> There is no reason to print warnings when balloon page allocation fails,
> as they are expected and can be handled gracefully.  Since VMware
> balloon now uses balloon-compaction infrastructure, and suppressed these
> warnings before, it is also beneficial to suppress these warnings to
> keep the same behavior that the balloon had before.

I am not sure if that's a good idea. The allocation warnings are usually
the only trace of "the user/admin did something bad because he/she tried
to inflate the balloon to an unsafe value". Believe me, I processed a
couple of such bugreports related to virtio-balloon and the warning were
very helpful for that.

> 
> Cc: Jason Wang <jasowang@...hat.com>
> Signed-off-by: Nadav Amit <namit@...are.com>
> ---
>  mm/balloon_compaction.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
> index 798275a51887..26de020aae7b 100644
> --- a/mm/balloon_compaction.c
> +++ b/mm/balloon_compaction.c
> @@ -124,7 +124,8 @@ EXPORT_SYMBOL_GPL(balloon_page_list_dequeue);
>  struct page *balloon_page_alloc(void)
>  {
>  	struct page *page = alloc_page(balloon_mapping_gfp_mask() |
> -				       __GFP_NOMEMALLOC | __GFP_NORETRY);
> +				       __GFP_NOMEMALLOC | __GFP_NORETRY |
> +				       __GFP_NOWARN);
>  	return page;
>  }
>  EXPORT_SYMBOL_GPL(balloon_page_alloc);
> 


-- 

Thanks,

David / dhildenb