From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Fri, 11 Jul 2014 07:55:50 -0700 (PDT) From: Hugh Dickins To: Peter Zijlstra cc: Sasha Levin , Hugh Dickins , Heiko Carstens , Vlastimil Babka , akpm@linux-foundation.org, davej@redhat.com, koct9i@gmail.com, lczerner@redhat.com, stable@vger.kernel.org, "linux-mm@kvack.org" , LKML Subject: Re: + shmem-fix-faulting-into-a-hole-while-its-punched-take-2.patch added to -mm tree In-Reply-To: <53BFD708.1040305@oracle.com> Message-ID: References: <53BD1053.5020401@suse.cz> <53BD39FC.7040205@oracle.com> <53BD67DC.9040700@oracle.com> <53BE8B1B.3000808@oracle.com> <53BECBA4.3010508@oracle.com> <53BED7F6.4090502@oracle.com> <53BEE345.4090203@oracle.com> <20140711082500.GB20603@laptop.programming.kicks-ass.net> <53BFD708.1040305@oracle.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: On Fri, 11 Jul 2014, Sasha Levin wrote: > > There's no easy way to see whether a given task is actually holding a lock or > is just blocking on it without going through all those tasks one by one and > looking at their trace. > > I agree with you that "The call trace is very clear on it that its not", but > when you have 500 call traces you really want something better than going > through it one call trace at a time. Points well made, and I strongly agree with Vlastimil and Sasha. There is a world of difference between a lock wanted and a lock held, and for the display of locks "held" to conceal that difference is unhelpful. It just needs one greppable word to distinguish the cases. (Though I didn't find "The call trace is very clear on it that its not", I thought it too was telling me that the lock was already held somehow.) Hugh