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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id DCC15C4706C for ; Fri, 12 Jan 2024 16:08:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 05DB46B0087; Fri, 12 Jan 2024 11:08:14 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 00DF66B0089; Fri, 12 Jan 2024 11:08:13 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E3F046B008C; Fri, 12 Jan 2024 11:08:13 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id D4E736B0087 for ; Fri, 12 Jan 2024 11:08:13 -0500 (EST) Received: from smtpin24.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id A51C01C0C18 for ; Fri, 12 Jan 2024 16:08:13 +0000 (UTC) X-FDA: 81671140866.24.E7AF84F Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com [94.136.29.106]) by imf12.hostedemail.com (Postfix) with ESMTP id 85D3F4001A for ; Fri, 12 Jan 2024 16:08:11 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=none; spf=pass (imf12.hostedemail.com: domain of f.weber@proxmox.com designates 94.136.29.106 as permitted sender) smtp.mailfrom=f.weber@proxmox.com; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1705075692; a=rsa-sha256; cv=none; b=CVNM1aUFz0vsErp3pORicu81aSEejzW0v75/OV3seXz7oRWIQvrZ6iRET8pZOqDhx3ApbU yS42r0xGQ+UrVmxrasojUxhNy0aB+wHly+VdXoU20ZQFDQzCHVNREoP9TnIfgC6ZgCvLHW FspZIFaeuBh/zKgCt95fXPi1QyOws14= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=none; spf=pass (imf12.hostedemail.com: domain of f.weber@proxmox.com designates 94.136.29.106 as permitted sender) smtp.mailfrom=f.weber@proxmox.com; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1705075692; h=from:from:sender: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; bh=bEPAXXjH5KC2IoBAP+LyevfUT2wsF8VFR9Py4S3M9T4=; b=Dfep1ldveLrlBnyTIAOdrbekWneR37vL5sR1JtYtDnQdYwdj2oui5HtvkRflQJD52FzVx2 ka9w+/IQ8tPplxOOvwe4i294WR+jZniXh30E2UjbAgCOaKy7Loo+ZkokI2WXy5IsTx2RU0 2cpipQFzDQ7HKGawBXYd/lx9tDE/Au4= Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 46C69490CC; Fri, 12 Jan 2024 17:08:09 +0100 (CET) Message-ID: <533e4b73-105c-401d-b496-25d20eba2d76@proxmox.com> Date: Fri, 12 Jan 2024 17:08:08 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Temporary KVM guest hangs connected to KSM and NUMA balancer Content-Language: en-US To: Sean Christopherson Cc: kvm@vger.kernel.org, Paolo Bonzini , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <832697b9-3652-422d-a019-8c0574a188ac@proxmox.com> From: Friedrich Weber In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 85D3F4001A X-Stat-Signature: o9o3n9s9xu1jr759tp47ydebwetnqseu X-HE-Tag: 1705075691-259077 X-HE-Meta: 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 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: List-Subscribe: List-Unsubscribe: On 11/01/2024 17:00, Sean Christopherson wrote: > This is a known issue. It's mostly a KVM bug[1][2] (fix posted[3]), but I suspect > that a bug in the dynamic preemption model logic[4] is also contributing to the > behavior by causing KVM to yield on preempt models where it really shouldn't. Thanks a lot for the pointers and the proposed fixes! I still see the same temporary hangs with [3] applied on top of 6.7 (0dd3ee31). However, with [4] applied in addition, I have not seen any temporary hangs yet. As the v1 of [3] was reported to fix the reported bug [2] and looks very similar to the v2 I tried, I wonder whether I might be seeing a slightly different kind of hangs than the one reported in [2] -- also because the reproducer relies heavily on KSM and AFAICT, KSM was entirely disabled in [2]. I'll try to run a few more tests next week. FWIW, the kernel config relevant to preemption: CONFIG_PREEMPT_BUILD=y # CONFIG_PREEMPT_NONE is not set CONFIG_PREEMPT_VOLUNTARY=y # CONFIG_PREEMPT is not set CONFIG_PREEMPT_COUNT=y CONFIG_PREEMPTION=y CONFIG_PREEMPT_DYNAMIC=y CONFIG_PREEMPT_RCU=y CONFIG_HAVE_PREEMPT_DYNAMIC=y CONFIG_HAVE_PREEMPT_DYNAMIC_CALL=y CONFIG_PREEMPT_NOTIFIERS=y CONFIG_DRM_I915_PREEMPT_TIMEOUT=640 CONFIG_DRM_I915_PREEMPT_TIMEOUT_COMPUTE=7500 # CONFIG_DEBUG_PREEMPT is not set # CONFIG_PREEMPT_TRACER is not set # CONFIG_PREEMPTIRQ_DELAY_TEST is not set Thanks again! Friedrich > [1] https://lore.kernel.org/all/ZNnPF4W26ZbAyGto@yzhao56-desk.sh.intel.com > [2] https://lore.kernel.org/all/bug-218259-28872@https.bugzilla.kernel.org%2F > [3] https://lore.kernel.org/all/20240110012045.505046-1-seanjc@google.com > [4] https://lore.kernel.org/all/20240110214723.695930-1-seanjc@google.com