From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id 436BE6B007B for ; Tue, 24 Nov 2009 15:59:47 -0500 (EST) Received: by fg-out-1718.google.com with SMTP id d23so2591011fga.8 for ; Tue, 24 Nov 2009 12:59:45 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20091124162311.GA8679@linux.vnet.ibm.com> References: <20091118181202.GA12180@linux.vnet.ibm.com> <84144f020911192249l6c7fa495t1a05294c8f5b6ac8@mail.gmail.com> <1258709153.11284.429.camel@laptop> <84144f020911200238w3d3ecb38k92ca595beee31de5@mail.gmail.com> <1258714328.11284.522.camel@laptop> <4B067816.6070304@cs.helsinki.fi> <1258729748.4104.223.camel@laptop> <1259002800.5630.1.camel@penberg-laptop> <20091124162311.GA8679@linux.vnet.ibm.com> Date: Tue, 24 Nov 2009 22:59:44 +0200 Message-ID: <84144f020911241259r3a604b29yb59902655ec03a20@mail.gmail.com> Subject: Re: lockdep complaints in slab allocator From: Pekka Enberg Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org To: paulmck@linux.vnet.ibm.com Cc: Peter Zijlstra , linux-mm@kvack.org, cl@linux-foundation.org, mpm@selenic.com, LKML , Nick Piggin List-ID: On Tue, Nov 24, 2009 at 6:23 PM, Paul E. McKenney wrote: > On Mon, Nov 23, 2009 at 09:00:00PM +0200, Pekka Enberg wrote: >> Hi Peter, >> >> On Fri, 2009-11-20 at 16:09 +0100, Peter Zijlstra wrote: >> > > Uh, ok, so apparently I was right after all. There's a comment in >> > > free_block() above the slab_destroy() call that refers to the commen= t >> > > above alloc_slabmgmt() function definition which explains it all. >> > > >> > > Long story short: ->slab_cachep never points to the same kmalloc cac= he >> > > we're allocating or freeing from. Where do we need to put the >> > > spin_lock_nested() annotation? Would it be enough to just use it in >> > > cache_free_alien() for alien->lock or do we need it in >> > > cache_flusharray() as well? >> > >> > You'd have to somehow push the nested state down from the >> > kmem_cache_free() call in slab_destroy() to all nc->lock sites below. >> >> That turns out to be _very_ hard. How about something like the following >> untested patch which delays slab_destroy() while we're under nc->lock. >> >> =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 Pekka > > Preliminary tests look good! =A0The test was a ten-hour rcutorture run on > an 8-CPU Power system with a half-second delay between randomly chosen > CPU-hotplug operations. =A0No lockdep warnings. =A0;-) > > Will keep hammering on it. Thanks! Please let me know when you're hammered it enough :-). Peter, may I have your ACK or NAK on the patch, please? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org