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 A0B0DC47258 for ; Wed, 17 Jan 2024 13:09:35 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1E0296B00CC; Wed, 17 Jan 2024 08:09:35 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1905C6B00D1; Wed, 17 Jan 2024 08:09:35 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 07F3A6B00D5; Wed, 17 Jan 2024 08:09:35 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id ED84A6B00CC for ; Wed, 17 Jan 2024 08:09:34 -0500 (EST) Received: from smtpin06.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id A1C6C140354 for ; Wed, 17 Jan 2024 13:09:34 +0000 (UTC) X-FDA: 81688834668.06.62F6917 Received: from proxmox-new.maurer-it.com (proxmox-new.maurer-it.com [94.136.29.106]) by imf13.hostedemail.com (Postfix) with ESMTP id B573020017 for ; Wed, 17 Jan 2024 13:09:31 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf13.hostedemail.com: domain of f.weber@proxmox.com designates 94.136.29.106 as permitted sender) smtp.mailfrom=f.weber@proxmox.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1705496972; 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=lMaBnHLDNKZRAPQX5DsGrPNmq+ZmSI3o5caWklPO7BE=; b=Pe+3jJLJfQAXbSZzg28XsMLNQxmROXLfi7LWuKVA/0GyNnh7SzZZ8r4Aj2+7ruudwdHiwc qAeqYgsqtTOlDlzFY7rZByk40TcViHzRz5jFNUBzMgKj2kiH/hnP/PewO7r7L4pCI8eDo0 tY55ZU72awaeFLzXbSbewzs69Hv30dg= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf13.hostedemail.com: domain of f.weber@proxmox.com designates 94.136.29.106 as permitted sender) smtp.mailfrom=f.weber@proxmox.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1705496972; a=rsa-sha256; cv=none; b=eMdvrCOv6z5lm3Ifae2KuVufVVVgZ5c8grOy98WC3JuNHH+C2vBPb52sWHXjpkAaVS7jro sj0y71qa94d3bNH3xhVWvqS/xIvVScvxNqiKxmhEMroWe9a6Fok7rMoqm3TSqqmAmScyk8 UdLSA0YJCaNY2bxzEoULqkSgfIWzpbk= Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 69F82457C2; Wed, 17 Jan 2024 14:09:29 +0100 (CET) Message-ID: Date: Wed, 17 Jan 2024 14:09:28 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: Temporary KVM guest hangs connected to KSM and NUMA balancer 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> Content-Language: en-US From: Friedrich Weber In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: B573020017 X-Rspam-User: X-Rspamd-Server: rspam04 X-Stat-Signature: rdfruusxofdy3ongdgj4sot48f83598y X-HE-Tag: 1705496971-147222 X-HE-Meta: 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 xLI+Lnk5 18AjdFFjVWN057KOKNASJOA/dzXsy34jrfWBN8Y87Xy73nvTYkx04G8e2BOyCbv3fHwI86rd00JJk+jaXNmV0l8RHQWUXZ5mb8BE+r+JF/5M+N32CGXMab1C7r2CrNSeRnNQADenDc6wpWsY= 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 16/01/2024 18:20, Sean Christopherson wrote: >> Does this make sense to you? Happy to double-check or run more tests if >> anything seems off. > > Ha! It too me a few minutes to realize what went sideways with v2. KVM has an > in-flight change that switches from host virtual addresses (HVA) to guest physical > frame numbers (GFN) for the retry check, commit 8569992d64b8 ("KVM: Use gfn instead > of hva for mmu_notifier_retry"). > > That commit is in the KVM pull request for 6.8, and so v2 is based on top of a > branch that contains said commit. But for better or worse (probably worse), the > switch from HVA=GFN didn't change the _names_ of mmu_invalidate_range_{start,end}, > only the type. So v2 applies and compiles cleanly on 6.7, but it's subtly broken > because checking for a GFN match against an HVA range is all but guaranteed to get > false negatives. Oof, that's nifty, good catch! I'll pay more attention to the base-commit when testing next time. :) > If you can try v2 on top of `git://git.kernel.org/pub/scm/virt/kvm/kvm.git next`, > that would be helpful to confirm that I didn't screw up something else. Pulled that repository and can confirm: * 1c6d984f ("x86/kvm: Do not try to disable kvmclock if it was not enabled", current `next`): reproducer hangs * v2 [1] ("KVM: x86/mmu: Retry fault before acquiring mmu_lock if mapping is changing") applied on top of 1c6d984f: no hangs anymore If I understand the discussion on [1] correctly, there might be a v3 -- if so, I'll happily test that too. > Thanks very much for reporting back! I'm pretty sure we would have missed the > semantic conflict when backporting the fix to 6.7 and earlier, i.e. you likely > saved us from another round of bug reports for various stable trees. Sure! Thanks a lot for taking a look at this! Best wishes, Friedrich [1] https://lore.kernel.org/all/20240110012045.505046-1-seanjc@google.com/