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[192.55.52.115]) by mx.google.com with ESMTPS id b92si684669pjc.17.2019.07.17.23.24.28 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 17 Jul 2019 23:24:29 -0700 (PDT) Received-SPF: pass (google.com: domain of wei.w.wang@intel.com designates 192.55.52.115 as permitted sender) client-ip=192.55.52.115; Authentication-Results: mx.google.com; spf=pass (google.com: domain of wei.w.wang@intel.com designates 192.55.52.115 as permitted sender) smtp.mailfrom=wei.w.wang@intel.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=intel.com X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 17 Jul 2019 23:24:28 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,276,1559545200"; d="scan'208";a="191506353" Received: from unknown (HELO [10.239.13.7]) ([10.239.13.7]) by fmsmga004.fm.intel.com with ESMTP; 17 Jul 2019 23:24:25 -0700 Message-ID: <5D3011E9.4040908@intel.com> Date: Thu, 18 Jul 2019 14:30:01 +0800 From: Wei Wang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: "Michael S. Tsirkin" CC: Alexander Duyck , Nitesh Narayan Lal , kvm list , David Hildenbrand , "Hansen, Dave" , LKML , linux-mm , Andrew Morton , Yang Zhang , "pagupta@redhat.com" , Rik van Riel , Konrad Rzeszutek Wilk , "lcapitulino@redhat.com" , Andrea Arcangeli , Paolo Bonzini , "Williams, Dan J" , Alexander Duyck Subject: Re: use of shrinker in virtio balloon free page hinting References: <20190717071332-mutt-send-email-mst@kernel.org> <286AC319A985734F985F78AFA26841F73E16D4B2@shsmsx102.ccr.corp.intel.com> <20190718000434-mutt-send-email-mst@kernel.org> <5D300A32.4090300@intel.com> <20190718015319-mutt-send-email-mst@kernel.org> In-Reply-To: <20190718015319-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 07/18/2019 01:58 PM, Michael S. Tsirkin wrote: > > what if it does not fail? > > >> Shrinker is called on system memory pressure. On memory pressure >> get_free_page_and_send will fail memory allocation, so it stops allocating >> more. > Memory pressure could be triggered by an unrelated allocation > e.g. from another driver. As memory pressure is system-wide (no matter who triggers it), free page hinting will fail on memory pressure, same as other drivers. As long as the page allocation succeeds, we could just think the system is not in the memory pressure situation, then thing could go on normally. Also, the VIRTIO_BALLOON_FREE_PAGE_ALLOC_FLAG includes NORETRY and NOMEMALLOC, which makes it easier than most other drivers to fail allocation first. Best, Wei