From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 03C55C433DF for ; Thu, 18 Jun 2020 09:07:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D2F9021924 for ; Thu, 18 Jun 2020 09:07:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="QZ23tj3L" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728920AbgFRJHU (ORCPT ); Thu, 18 Jun 2020 05:07:20 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:26453 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1728588AbgFRJHQ (ORCPT ); Thu, 18 Jun 2020 05:07:16 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1592471234; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=zph7qfgsNm0uG10f1WSBDBIX+C5pgP3v2hrfa3bjGas=; b=QZ23tj3LZoGFyqtVS09+7VriySZXprn2dudRAQsg6B53k13g5auQt9PyTMp4lM1FCA5S9a qRkCNcHyOk/2k7k+dUm3qyXTeTI+q5vUZZpXuwH9DDFXkdQb26bmW404KC2PDZUTxhHO8y ZcO7TbIC24O8nCFsQ5tQBqZ9KaELQNo= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-81-9_5xjY4nO3C6vlQFRovjOA-1; Thu, 18 Jun 2020 05:07:10 -0400 X-MC-Unique: 9_5xjY4nO3C6vlQFRovjOA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 50453100CCC0; Thu, 18 Jun 2020 09:07:09 +0000 (UTC) Received: from [10.36.114.105] (ovpn-114-105.ams2.redhat.com [10.36.114.105]) by smtp.corp.redhat.com (Postfix) with ESMTP id ECC597A01A; Thu, 18 Jun 2020 09:07:06 +0000 (UTC) Subject: Re: [PATCH] KVM: s390: reduce number of IO pins to 1 To: Christian Borntraeger , Janosch Frank Cc: KVM , Cornelia Huck , linux-s390 , Paolo Bonzini References: <20200617083620.5409-1-borntraeger@de.ibm.com> <6953c580-9b99-1c76-b6eb-510dcb70894c@de.ibm.com> From: David Hildenbrand Autocrypt: addr=david@redhat.com; prefer-encrypt=mutual; keydata= mQINBFXLn5EBEAC+zYvAFJxCBY9Tr1xZgcESmxVNI/0ffzE/ZQOiHJl6mGkmA1R7/uUpiCjJ dBrn+lhhOYjjNefFQou6478faXE6o2AhmebqT4KiQoUQFV4R7y1KMEKoSyy8hQaK1umALTdL QZLQMzNE74ap+GDK0wnacPQFpcG1AE9RMq3aeErY5tujekBS32jfC/7AnH7I0v1v1TbbK3Gp XNeiN4QroO+5qaSr0ID2sz5jtBLRb15RMre27E1ImpaIv2Jw8NJgW0k/D1RyKCwaTsgRdwuK Kx/Y91XuSBdz0uOyU/S8kM1+ag0wvsGlpBVxRR/xw/E8M7TEwuCZQArqqTCmkG6HGcXFT0V9 PXFNNgV5jXMQRwU0O/ztJIQqsE5LsUomE//bLwzj9IVsaQpKDqW6TAPjcdBDPLHvriq7kGjt WhVhdl0qEYB8lkBEU7V2Yb+SYhmhpDrti9Fq1EsmhiHSkxJcGREoMK/63r9WLZYI3+4W2rAc UucZa4OT27U5ZISjNg3Ev0rxU5UH2/pT4wJCfxwocmqaRr6UYmrtZmND89X0KigoFD/XSeVv jwBRNjPAubK9/k5NoRrYqztM9W6sJqrH8+UWZ1Idd/DdmogJh0gNC0+N42Za9yBRURfIdKSb B3JfpUqcWwE7vUaYrHG1nw54pLUoPG6sAA7Mehl3nd4pZUALHwARAQABtCREYXZpZCBIaWxk ZW5icmFuZCA8ZGF2aWRAcmVkaGF0LmNvbT6JAlgEEwEIAEICGwMFCQlmAYAGCwkIBwMCBhUI AgkKCwQWAgMBAh4BAheAFiEEG9nKrXNcTDpGDfzKTd4Q9wD/g1oFAl3pImkCGQEACgkQTd4Q 9wD/g1o+VA//SFvIHUAvul05u6wKv/pIR6aICPdpF9EIgEU448g+7FfDgQwcEny1pbEzAmiw zAXIQ9H0NZh96lcq+yDLtONnXk/bEYWHHUA014A1wqcYNRY8RvY1+eVHb0uu0KYQoXkzvu+s Dncuguk470XPnscL27hs8PgOP6QjG4jt75K2LfZ0eAqTOUCZTJxA8A7E9+XTYuU0hs7QVrWJ jQdFxQbRMrYz7uP8KmTK9/Cnvqehgl4EzyRaZppshruKMeyheBgvgJd5On1wWq4ZUV5PFM4x II3QbD3EJfWbaJMR55jI9dMFa+vK7MFz3rhWOkEx/QR959lfdRSTXdxs8V3zDvChcmRVGN8U Vo93d1YNtWnA9w6oCW1dnDZ4kgQZZSBIjp6iHcA08apzh7DPi08jL7M9UQByeYGr8KuR4i6e RZI6xhlZerUScVzn35ONwOC91VdYiQgjemiVLq1WDDZ3B7DIzUZ4RQTOaIWdtXBWb8zWakt/ ztGhsx0e39Gvt3391O1PgcA7ilhvqrBPemJrlb9xSPPRbaNAW39P8ws/UJnzSJqnHMVxbRZC Am4add/SM+OCP0w3xYss1jy9T+XdZa0lhUvJfLy7tNcjVG/sxkBXOaSC24MFPuwnoC9WvCVQ ZBxouph3kqc4Dt5X1EeXVLeba+466P1fe1rC8MbcwDkoUo65Ag0EVcufkQEQAOfX3n0g0fZz Bgm/S2zF/kxQKCEKP8ID+Vz8sy2GpDvveBq4H2Y34XWsT1zLJdvqPI4af4ZSMxuerWjXbVWb T6d4odQIG0fKx4F8NccDqbgHeZRNajXeeJ3R7gAzvWvQNLz4piHrO/B4tf8svmRBL0ZB5P5A 2uhdwLU3NZuK22zpNn4is87BPWF8HhY0L5fafgDMOqnf4guJVJPYNPhUFzXUbPqOKOkL8ojk CXxkOFHAbjstSK5Ca3fKquY3rdX3DNo+EL7FvAiw1mUtS+5GeYE+RMnDCsVFm/C7kY8c2d0G NWkB9pJM5+mnIoFNxy7YBcldYATVeOHoY4LyaUWNnAvFYWp08dHWfZo9WCiJMuTfgtH9tc75 7QanMVdPt6fDK8UUXIBLQ2TWr/sQKE9xtFuEmoQGlE1l6bGaDnnMLcYu+Asp3kDT0w4zYGsx 5r6XQVRH4+5N6eHZiaeYtFOujp5n+pjBaQK7wUUjDilPQ5QMzIuCL4YjVoylWiBNknvQWBXS lQCWmavOT9sttGQXdPCC5ynI+1ymZC1ORZKANLnRAb0NH/UCzcsstw2TAkFnMEbo9Zu9w7Kv AxBQXWeXhJI9XQssfrf4Gusdqx8nPEpfOqCtbbwJMATbHyqLt7/oz/5deGuwxgb65pWIzufa N7eop7uh+6bezi+rugUI+w6DABEBAAGJAiUEGAECAA8FAlXLn5ECGwwFCQlmAYAACgkQTd4Q 9wD/g1qA6w/+M+ggFv+JdVsz5+ZIc6MSyGUozASX+bmIuPeIecc9UsFRatc91LuJCKMkD9Uv GOcWSeFpLrSGRQ1Z7EMzFVU//qVs6uzhsNk0RYMyS0B6oloW3FpyQ+zOVylFWQCzoyyf227y GW8HnXunJSC+4PtlL2AY4yZjAVAPLK2l6mhgClVXTQ/S7cBoTQKP+jvVJOoYkpnFxWE9pn4t H5QIFk7Ip8TKr5k3fXVWk4lnUi9MTF/5L/mWqdyIO1s7cjharQCstfWCzWrVeVctpVoDfJWp 4LwTuQ5yEM2KcPeElLg5fR7WB2zH97oI6/Ko2DlovmfQqXh9xWozQt0iGy5tWzh6I0JrlcxJ ileZWLccC4XKD1037Hy2FLAjzfoWgwBLA6ULu0exOOdIa58H4PsXtkFPrUF980EEibUp0zFz GotRVekFAceUaRvAj7dh76cToeZkfsjAvBVb4COXuhgX6N4pofgNkW2AtgYu1nUsPAo+NftU CxrhjHtLn4QEBpkbErnXQyMjHpIatlYGutVMS91XTQXYydCh5crMPs7hYVsvnmGHIaB9ZMfB njnuI31KBiLUks+paRkHQlFcgS2N3gkRBzH7xSZ+t7Re3jvXdXEzKBbQ+dC3lpJB0wPnyMcX FOTT3aZT7IgePkt5iC/BKBk3hqKteTnJFeVIT7EC+a6YUFg= Organization: Red Hat GmbH Message-ID: <66419659-e678-2daf-2e02-4f2158076ddb@redhat.com> Date: Thu, 18 Jun 2020 11:07:05 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <6953c580-9b99-1c76-b6eb-510dcb70894c@de.ibm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On 17.06.20 13:04, Christian Borntraeger wrote: > > > On 17.06.20 12:19, David Hildenbrand wrote: >> On 17.06.20 10:36, Christian Borntraeger wrote: >>> The current number of KVM_IRQCHIP_NUM_PINS results in an order 3 >>> allocation (32kb) for each guest start/restart. This can result in OOM >>> killer activity even with free swap when the memory is fragmented >>> enough: >>> >>> kernel: qemu-system-s39 invoked oom-killer: gfp_mask=0x440dc0(GFP_KERNEL_ACCOUNT|__GFP_COMP|__GFP_ZERO), order=3, oom_score_adj=0 >>> kernel: CPU: 1 PID: 357274 Comm: qemu-system-s39 Kdump: loaded Not tainted 5.4.0-29-generic #33-Ubuntu >>> kernel: Hardware name: IBM 8562 T02 Z06 (LPAR) >>> kernel: Call Trace: >>> kernel: ([<00000001f848fe2a>] show_stack+0x7a/0xc0) >>> kernel: [<00000001f8d3437a>] dump_stack+0x8a/0xc0 >>> kernel: [<00000001f8687032>] dump_header+0x62/0x258 >>> kernel: [<00000001f8686122>] oom_kill_process+0x172/0x180 >>> kernel: [<00000001f8686abe>] out_of_memory+0xee/0x580 >>> kernel: [<00000001f86e66b8>] __alloc_pages_slowpath+0xd18/0xe90 >>> kernel: [<00000001f86e6ad4>] __alloc_pages_nodemask+0x2a4/0x320 >>> kernel: [<00000001f86b1ab4>] kmalloc_order+0x34/0xb0 >>> kernel: [<00000001f86b1b62>] kmalloc_order_trace+0x32/0xe0 >>> kernel: [<00000001f84bb806>] kvm_set_irq_routing+0xa6/0x2e0 >>> kernel: [<00000001f84c99a4>] kvm_arch_vm_ioctl+0x544/0x9e0 >>> kernel: [<00000001f84b8936>] kvm_vm_ioctl+0x396/0x760 >>> kernel: [<00000001f875df66>] do_vfs_ioctl+0x376/0x690 >>> kernel: [<00000001f875e304>] ksys_ioctl+0x84/0xb0 >>> kernel: [<00000001f875e39a>] __s390x_sys_ioctl+0x2a/0x40 >>> kernel: [<00000001f8d55424>] system_call+0xd8/0x2c8 >>> >>> As far as I can tell s390x does not use the iopins as we bail our for >>> anything other than KVM_IRQ_ROUTING_S390_ADAPTER and the chip/pin is >>> only used for KVM_IRQ_ROUTING_IRQCHIP. So let us use a small number to >>> reduce the memory footprint. >>> >>> Signed-off-by: Christian Borntraeger >>> --- >>> arch/s390/include/asm/kvm_host.h | 8 ++++---- >>> 1 file changed, 4 insertions(+), 4 deletions(-) >>> >>> diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h >>> index cee3cb6455a2..6ea0820e7c7f 100644 >>> --- a/arch/s390/include/asm/kvm_host.h >>> +++ b/arch/s390/include/asm/kvm_host.h >>> @@ -31,12 +31,12 @@ >>> #define KVM_USER_MEM_SLOTS 32 >>> >>> /* >>> - * These seem to be used for allocating ->chip in the routing table, >>> - * which we don't use. 4096 is an out-of-thin-air value. If we need >>> - * to look at ->chip later on, we'll need to revisit this. >>> + * These seem to be used for allocating ->chip in the routing table, which we >>> + * don't use. 1 is as small as we can get to reduce the needed memory. If we >>> + * need to look at ->chip later on, we'll need to revisit this. >>> */ >>> #define KVM_NR_IRQCHIPS 1 >>> -#define KVM_IRQCHIP_NUM_PINS 4096 >>> +#define KVM_IRQCHIP_NUM_PINS 1 >>> #define KVM_HALT_POLL_NS_DEFAULT 50000 >>> >>> /* s390-specific vcpu->requests bit members */ >>> >> >> Guess it doesn't make sense to wrap all the "->chip" handling in a >> separate set of defines. >> >> Reviewed-by: David Hildenbrand > > I guess this is just the most simple solution. I am asking myself if I should add > cc stable of Fixes as I was able to trigger this by having several guests with a > reboot loop and several guests that trigger memory overcommitment. > I don't think this classifies as stable material. -- Thanks, David / dhildenb