From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id 05B388D0040 for ; Fri, 25 Mar 2011 11:47:20 -0400 (EDT) Date: Fri, 25 Mar 2011 10:45:24 -0500 (CDT) From: Christoph Lameter Subject: Re: [GIT PULL] SLAB changes for v2.6.39-rc1 In-Reply-To: <20110325151353.GG1409@htj.dyndns.org> Message-ID: References: <20110324185903.GA30510@elte.hu> <20110324193647.GA7957@elte.hu> <1300997290.2714.2.camel@edumazet-laptop> <20110325151353.GG1409@htj.dyndns.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Tejun Heo Cc: Eric Dumazet , Pekka Enberg , Ingo Molnar , torvalds@linux-foundation.org, akpm@linux-foundation.org, npiggin@kernel.dk, David Rientjes , linux-kernel@vger.kernel.org, linux-mm@kvack.org On Fri, 25 Mar 2011, Tejun Heo wrote: > I've looked through the code but can't figure out what the difference > is. The memset code is in mm/percpu-vm.c::pcpu_populate_chunk(). > > for_each_possible_cpu(cpu) > memset((void *)pcpu_chunk_addr(chunk, cpu, 0) + off, 0, size); > > (pcpu_chunk_addr(chunk, cpu, 0) + off) is the same vaddr as will be > obtained by per_cpu_ptr(ptr, cpu), so all allocated memory regions are > accessed before being returned. Dazed and confused (seems like the > theme of today for me). > > Could it be that the vmalloc page is taking more than one faults? The vmalloc page only contains per cpu data from a single cpu right? Could anyone have set write access restrictions that would require a fault to get rid of? Or does an access from a different cpu require a "page table sync"? There is some rather strange looking code in arch/x86/mm/fault.c:vmalloc_fault -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org