linux-kernel - Re: [PATCH v2] mm/balloon_compaction: Informative allocation warnings

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Date:   Wed, 21 Aug 2019 20:57:57 +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 v2] mm/balloon_compaction: Informative allocation warnings

On 21.08.19 11:41, Nadav Amit wrote:
> There is no reason to print generic warnings when balloon memory
> allocation fails, as failures 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.
> 
> Since such warnings can still be useful to indicate that the balloon is
> over-inflated, print more informative and less frightening warning if
> allocation fails instead.
> 
> Cc: David Hildenbrand <david@...hat.com>
> Cc: Jason Wang <jasowang@...hat.com>
> Signed-off-by: Nadav Amit <namit@...are.com>
> 
> ---
> 
> v1->v2:
>   * Print informative warnings instead suppressing [David]
> ---
>  mm/balloon_compaction.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
> index 798275a51887..0c1d1f7689f0 100644
> --- a/mm/balloon_compaction.c
> +++ b/mm/balloon_compaction.c
> @@ -124,7 +124,12 @@ 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);
> +
> +	if (!page)
> +		pr_warn_ratelimited("memory balloon: memory allocation failed");
> +
>  	return page;
>  }
>  EXPORT_SYMBOL_GPL(balloon_page_alloc);
> 

Not sure if "memory balloon" is the right wording. hmmm.

Acked-by: David Hildenbrand <david@...hat.com>

-- 

Thanks,

David / dhildenb