From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sedat Dilek Subject: Re: linux-next: Tree for Feb 4 Date: Thu, 5 Feb 2015 15:57:12 +0100 Message-ID: References: <20150204193535.58f132c5@canb.auug.org.au> <1511573.AlfExlvQsO@vostro.rjw.lan> <20150204215357.GL5370@linux.vnet.ibm.com> <11131483.LrRNxJumiL@vostro.rjw.lan> <20150204235115.GP5370@linux.vnet.ibm.com> <20150205001019.GA12362@linux.vnet.ibm.com> <20150205005716.GS5370@linux.vnet.ibm.com> <20150205015144.GT5370@linux.vnet.ibm.com> <54D3186F.7030500@sr71.net> Reply-To: sedat.dilek@gmail.com Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: In-Reply-To: <54D3186F.7030500@sr71.net> Sender: linux-kernel-owner@vger.kernel.org To: Dave Hansen Cc: Paul McKenney , "Rafael J. Wysocki" , "Rafael J. Wysocki" , linux-next , LKML , Stephen Rothwell , Kristen Carlson Accardi , "H. Peter Anvin" , Rik van Riel , Mel Gorman , Steven Rostedt List-Id: linux-next.vger.kernel.org On Thu, Feb 5, 2015 at 8:14 AM, Dave Hansen wrote: > On 02/04/2015 05:53 PM, Sedat Dilek wrote: >> The architecture-specific switch_mm() function can be called by offline >> CPUs, but includes event tracing, which cannot be legally carried out >> on offline CPUs. This results in a lockdep-RCU splat. This commit fixes >> this splat by omitting the tracing when the CPU is offline. > ... >>>> >> > load_cr3(next->pgd); >>>> >> > - trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL); >>>> >> > + if (cpu_online(smp_processor_id())) >>>> >> > + trace_tlb_flush(TLB_FLUSH_ON_TASK_SWITCH, TLB_FLUSH_ALL); > > Is this, perhaps, something that we should be doing in the generic trace > code so that all of the trace users don't have to worry about it? Also, > this patch will add overhead to the code when tracing is off. It would > be best if we could manage to make the cpu_online() check only in the > cases where the tracepoint is on. Hi Dave, thanks for your feedback. I have just seen that I again see the call-trace. Maybe you can discuss with Paul and others or offer a proposal patch. I should really do something for my recovery (influenza). Instead of laying lazy in my bed I thought to update my Linux kernels and graphics driver stack which made me happy. Regards, - Sedat -