Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752259Ab2FLIsf (ORCPT ); Tue, 12 Jun 2012 04:48:35 -0400 Received: from mail-qc0-f174.google.com ([209.85.216.174]:42713 "EHLO mail-qc0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751639Ab2FLIsc convert rfc822-to-8bit (ORCPT ); Tue, 12 Jun 2012 04:48:32 -0400 MIME-Version: 1.0 Reply-To: sedat.dilek@gmail.com In-Reply-To: <20120612021352.GA2845@amt.cnet> References: <0669740d6e2f3648f1c5c9a50e72f6eb@mgebm.net> <20120611220719.GA27415@amt.cnet> <20120612021352.GA2845@amt.cnet> Date: Tue, 12 Jun 2012 10:48:31 +0200 Message-ID: Subject: Re: WARNING: at arch/x86/kernel/kvmclock.c:127 From: Sedat Dilek To: Marcelo Tosatti Cc: Eric B Munson , kvm@vger.kernel.org, LKML , Avi Kivity , Thomas Gleixner , Ingo Molnar , x86@kernel.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4011 Lines: 101 On Tue, Jun 12, 2012 at 4:13 AM, Marcelo Tosatti wrote: > On Mon, Jun 11, 2012 at 06:10:34PM -0400, Eric B Munson wrote: >> On Mon, 11 Jun 2012 19:07:19 -0300, Marcelo Tosatti wrote: >> >On Mon, Jun 11, 2012 at 05:47:00PM -0400, Eric B Munson wrote: >> >>On Sun, 10 Jun 2012 17:47:24 +0200, Sedat Dilek wrote: >> >>>Hi, >> >>> >> >>>I see the same warning especially when resuming from a suspend (see >> >>>timestamps >=30-35sec) between Linux v3.5-rc1..v3.5-rc2. >> >>> >> >>>$ sudo grep kvmclock.c /var/log/kern.log >> >>>Jun  4 21:11:32 fambox kernel: [  784.037237] WARNING: at >> >>>arch/x86/kernel/kvmclock.c:127 >> >>>kvm_check_and_clear_guest_paused+0x52/0x60() >> >>>Jun  5 20:35:57 fambox kernel: [ 1928.458060] WARNING: at >> >>>arch/x86/kernel/kvmclock.c:127 >> >>>kvm_check_and_clear_guest_paused+0x52/0x60() >> >>>Jun  8 09:35:52 fambox kernel: [ 3290.134637] WARNING: at >> >>>arch/x86/kernel/kvmclock.c:127 >> >>>kvm_check_and_clear_guest_paused+0x52/0x60() >> >>>Jun  8 09:35:52 fambox kernel: [ 3290.238592] WARNING: at >> >>>arch/x86/kernel/kvmclock.c:127 >> >>>kvm_check_and_clear_guest_paused+0x52/0x60() >> >>>Jun  8 12:11:20 fambox kernel: [ 5777.023571] WARNING: at >> >>>arch/x86/kernel/kvmclock.c:127 >> >>>kvm_check_and_clear_guest_paused+0x52/0x60() >> >>>Jun  9 13:32:50 fambox kernel: [ 2778.842695] WARNING: at >> >>>arch/x86/kernel/kvmclock.c:127 >> >>>kvm_check_and_clear_guest_paused+0x52/0x60() >> >>> >> >>>From [1]: >> >>> >> >>>"...The warning itself is not required for the check_and_clear >> >>>function and can be removed as far as I am concerned." >> >>> >> >>>From [2] commit 3b5d56b9317fa7b5407dff1aa7b115bf6cdbd494 >> >>("kvmclock: >> >>>Add functions to check if the host has stopped the vm") >> >>>... >> >>>+bool kvm_check_and_clear_guest_paused(void) >> >>>+{ >> >>>+       bool ret = false; >> >>>+       struct pvclock_vcpu_time_info *src; >> >>>+ >> >>>+       /* >> >>>+        * per_cpu() is safe here because this function is only >> >>>called from >> >>>+        * timer functions where preemption is already disabled. >> >>>+        */ >> >>>+       WARN_ON(!in_atomic()); >> >>>+       src = &__get_cpu_var(hv_clock); >> >>>+       if ((src->flags & PVCLOCK_GUEST_STOPPED) != 0) { >> >>>+               __this_cpu_and(hv_clock.flags, >> >>>~PVCLOCK_GUEST_STOPPED); >> >>>+               ret = true; >> >>>+       } >> >>>+ >> >>>+       return ret; >> >>>+} >> >>>+EXPORT_SYMBOL_GPL(kvm_check_and_clear_guest_paused); >> >>>+ >> >>>... >> >>>( The export macro was dropped in a followup commit. ) >> >>> >> >>>So you mean "WARN_ON(!in_atomic());" can be deleted? >> > >> >Yes. >> > >> >>When I wrote the patch originally, I was under the (incorrect) >> >>assumption that the watch dog was only ever reset in an atomic >> >>context.  Given that this is not the case, the warning can be >> >>removed.  Though before that happens, I have a question: if this is >> >>called outside of an atomic context, is the use of __get_cpu_Var() >> >>and __this_cpu_and() invalid? >> > >> >It remains valid because its called with interrupts >> >disabled (see migrate_hrtimers). >> >> Thank you, that was my assumption but I wanted to confirm.  I do not >> have access to my working kernel tree and won't for 2 days.  I can't >> get to the patch until late Wednesday so if someone else wants to >> work that up I'd appreciate it. >> >> Thanks, >> Eric > > Removed the warning in kvm.git master. > I am reading your email approx. 6hrs after you have sent it and I do NOT see the patch in [1]. Can you please send me the patch as an attachment, Thanks! - Sedat - [1] http://git.kernel.org/?p=virt/kvm/kvm.git;a=shortlog;h=refs/heads/master -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/