Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH v2] memcg: page_alloc: skip bulk allocator for
 __GFP_ACCOUNT
To:     Shakeel Butt <shakeelb@google.com>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Michal Hocko <mhocko@kernel.org>,
        Mel Gorman <mgorman@techsingularity.net>
Cc:     Uladzislau Rezki <urezki@gmail.com>, Roman Gushchin <guro@fb.com>,
        Matthew Wilcox <willy@infradead.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        cgroups@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
References: <20211014151607.2171970-1-shakeelb@google.com>
From:   Vasily Averin <vvs@virtuozzo.com>
Message-ID: <9c6ecab8-9227-48ac-22d5-c1d96b85883a@virtuozzo.com>
Date:   Fri, 15 Oct 2021 15:19:18 +0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.13.0
MIME-Version: 1.0
In-Reply-To: <20211014151607.2171970-1-shakeelb@google.com>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 14.10.2021 18:16, Shakeel Butt wrote:
> The commit 5c1f4e690eec ("mm/vmalloc: switch to bulk allocator in
> __vmalloc_area_node()") switched to bulk page allocator for order 0
> allocation backing vmalloc. However bulk page allocator does not support
> __GFP_ACCOUNT allocations and there are several users of
> kvmalloc(__GFP_ACCOUNT).
> 
> For now make __GFP_ACCOUNT allocations bypass bulk page allocator. In
> future if there is workload that can be significantly improved with the
> bulk page allocator with __GFP_ACCCOUNT support, we can revisit the
> decision.
> 
> Fixes: 5c1f4e690eec ("mm/vmalloc: switch to bulk allocator in __vmalloc_area_node()")
> Signed-off-by: Shakeel Butt <shakeelb@google.com>

Reported-and-tested-by: Vasily Averin <vvs@virtuozzo.com>

> ---
> Changes since v1:
> - do fallback allocation instead of failure, suggested by Michal Hocko.
> - Added memcg_kmem_enabled() check, corrected by Vasily Averin
> 
>  mm/page_alloc.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 668edb16446a..9ca871dc8602 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5230,6 +5230,10 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid,
>  	if (unlikely(page_array && nr_pages - nr_populated == 0))
>  		goto out;
>  
> +	/* Bulk allocator does not support memcg accounting. */
> +	if (memcg_kmem_enabled() && (gfp & __GFP_ACCOUNT))
> +		goto failed;
> +
>  	/* Use the single page allocator for one page. */
>  	if (nr_pages - nr_populated == 1)
>  		goto failed;
>