Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161769Ab3DENVl (ORCPT ); Fri, 5 Apr 2013 09:21:41 -0400 Received: from shelob.surriel.com ([74.92.59.67]:46380 "EHLO shelob.surriel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161152Ab3DENVk (ORCPT ); Fri, 5 Apr 2013 09:21:40 -0400 Message-ID: <515ECFD0.4090202@surriel.com> Date: Fri, 05 Apr 2013 09:21:20 -0400 From: Rik van Riel User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130110 Thunderbird/17.0.2 MIME-Version: 1.0 To: Mike Galbraith CC: Sasha Levin , Davidlohr Bueso , torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, hhuang@redhat.com, jason.low2@hp.com, walken@google.com, lwoodman@redhat.com, chegu_vinod@hp.com, "Paul E. McKenney" Subject: Re: [PATCH -mm -next] ipc,sem: untangle RCU locking with find_alloc_undo References: <1363809337-29718-1-git-send-email-riel@surriel.com> <5151DBD3.6080201@oracle.com> <1364320297.5146.7.camel@buesod1.americas.hpqcorp.net> <5151E3D2.1070103@oracle.com> <20130326160059.7b466a8d@annuminas.surriel.com> <1365136697.4579.12.camel@marge.simpson.net> In-Reply-To: <1365136697.4579.12.camel@marge.simpson.net> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1102 Lines: 31 On 04/05/2013 12:38 AM, Mike Galbraith wrote: > On Tue, 2013-03-26 at 16:00 -0400, Rik van Riel wrote: >> The ipc semaphore code has a nasty RCU locking tangle, with both >> find_alloc_undo and semtimedop taking the rcu_read_lock(). The >> code can be cleaned up somewhat by only taking the rcu_read_lock >> once. >> >> There are no other callers to find_alloc_undo. >> >> This should also solve the trinity issue reported by Sasha Levin. > > I take it this is on top of the patchlet Sasha submitted? Indeed, and all the other fixes that got submitted :) > (I hit rcu stall banging on patch set in rt with 60 synchronized core > executive model if I let it run long enough, fwtw) What are you using to trigger an rcu stall? >> Reported-by: Sasha Levin >> Signed-off-by: Rik van Riel -- All rights reversed. -- 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/