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[81.185.168.95]) by smtp.gmail.com with ESMTPSA id d69sm5515728wmd.4.2019.08.30.08.11.58 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 30 Aug 2019 08:11:58 -0700 (PDT) Subject: Re: [PATCH] net/skbuff: silence warnings under memory pressure To: Qian Cai , davem@davemloft.net Cc: netdev@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <1567177025-11016-1-git-send-email-cai@lca.pw> From: Eric Dumazet Message-ID: <6109dab4-4061-8fee-96ac-320adf94e130@gmail.com> Date: Fri, 30 Aug 2019 17:11:57 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <1567177025-11016-1-git-send-email-cai@lca.pw> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000071, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 8/30/19 4:57 PM, Qian Cai wrote: > When running heavy memory pressure workloads, the system is throwing > endless warnings below due to the allocation could fail from > __build_skb(), and the volume of this call could be huge which may > generate a lot of serial console output and cosumes all CPUs as > warn_alloc() could be expensive by calling dump_stack() and then > show_mem(). > > Fix it by silencing the warning in this call site. Also, it seems > unnecessary to even print a warning at all if the allocation failed in > __build_skb(), as it may just retransmit the packet and retry. > Same patches are showing up there and there from time to time. Why is this particular spot interesting, against all others not adding __GFP_NOWARN ? Are we going to have hundred of patches adding __GFP_NOWARN at various points, or should we get something generic to not flood the syslog in case of memory pressure ?