From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f197.google.com (mail-wr0-f197.google.com [209.85.128.197]) by kanga.kvack.org (Postfix) with ESMTP id 31E3C6B0003 for ; Thu, 21 Jun 2018 03:54:54 -0400 (EDT) Received: by mail-wr0-f197.google.com with SMTP id i2-v6so1685604wrm.5 for ; Thu, 21 Jun 2018 00:54:54 -0700 (PDT) Received: from mx2.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id m28-v6si2241153eda.442.2018.06.21.00.54.52 for (version=TLS1 cipher=AES128-SHA bits=128/128); Thu, 21 Jun 2018 00:54:52 -0700 (PDT) Date: Thu, 21 Jun 2018 09:54:51 +0200 From: Michal Hocko Subject: Re: [patch] mm, oom: fix unnecessary killing of additional processes Message-ID: <20180621075451.GD10465@dhcp22.suse.cz> References: <20180615065541.GA24039@dhcp22.suse.cz> <20180619083316.GB13685@dhcp22.suse.cz> <20180620130311.GM13685@dhcp22.suse.cz> <20180621074537.GC10465@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180621074537.GC10465@dhcp22.suse.cz> Sender: owner-linux-mm@kvack.org List-ID: To: David Rientjes Cc: Andrew Morton , Tetsuo Handa , "Aneesh Kumar K.V" , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Thu 21-06-18 09:45:37, Michal Hocko wrote: > On Wed 20-06-18 13:34:52, David Rientjes wrote: > > On Wed, 20 Jun 2018, Michal Hocko wrote: [...] > > > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c > > > index 6bcecc325e7e..ac08f5d711be 100644 > > > --- a/arch/x86/kvm/x86.c > > > +++ b/arch/x86/kvm/x86.c > > > @@ -7203,8 +7203,9 @@ static void vcpu_load_eoi_exitmap(struct kvm_vcpu *vcpu) > > > kvm_x86_ops->load_eoi_exitmap(vcpu, eoi_exit_bitmap); > > > } > > > > > > -void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm, > > > - unsigned long start, unsigned long end) > > > +int kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm, > > > + unsigned long start, unsigned long end, > > > + bool blockable) > > > { > > > unsigned long apic_address; > > > > > > @@ -7215,6 +7216,8 @@ void kvm_arch_mmu_notifier_invalidate_range(struct kvm *kvm, > > > apic_address = gfn_to_hva(kvm, APIC_DEFAULT_PHYS_BASE >> PAGE_SHIFT); > > > if (start <= apic_address && apic_address < end) > > > kvm_make_all_cpus_request(kvm, KVM_REQ_APIC_PAGE_RELOAD); > > > + > > > + return 0; > > > } > > > > > > void kvm_vcpu_reload_apic_access_page(struct kvm_vcpu *vcpu) > > > > Auditing the first change in the patch, this is incorrect because > > kvm_make_all_cpus_request() for KVM_REQ_APIC_PAGE_RELOAD can block in > > kvm_kick_many_cpus() and that is after kvm_make_request() has been done. > > I would have to check the code closer. But doesn't > kvm_make_all_cpus_request call get_cpu which is preempt_disable? Sorry I meant kvm_make_vcpus_request_mask. kvm_make_all_cpus_request only does a GFP_ATOMIC allocation on top. -- Michal Hocko SUSE Labs