From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f173.google.com (mail-pd0-f173.google.com [209.85.192.173]) by kanga.kvack.org (Postfix) with ESMTP id 5B67D6B0038 for ; Tue, 24 Mar 2015 11:01:01 -0400 (EDT) Received: by pdbni2 with SMTP id ni2so223898378pdb.1 for ; Tue, 24 Mar 2015 08:01:01 -0700 (PDT) Received: from homiemail-a72.g.dreamhost.com (sub4.mail.dreamhost.com. [69.163.253.135]) by mx.google.com with ESMTP id ns9si5883549pbc.151.2015.03.24.08.00.59 for ; Tue, 24 Mar 2015 08:01:00 -0700 (PDT) Date: Tue, 24 Mar 2015 10:57:53 -0400 From: Bob Picco Subject: Re: 4.0.0-rc4: panic in free_block Message-ID: <20150324145753.GC10685@zareason> References: <550F5852.5020405@oracle.com> <20150322.220024.1171832215344978787.davem@davemloft.net> <20150322.221906.1670737065885267482.davem@davemloft.net> <20150323.122530.812870422534676208.davem@davemloft.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150323.122530.812870422534676208.davem@davemloft.net> Sender: owner-linux-mm@kvack.org List-ID: To: David Miller Cc: david.ahern@oracle.com, torvalds@linux-foundation.org, sparclinux@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, bpicco@meloft.net David Miller wrote: [Mon Mar 23 2015, 12:25:30PM EDT] > From: David Miller > Date: Sun, 22 Mar 2015 22:19:06 -0400 (EDT) > > > I'll work on a fix. > > Ok, here is what I committed. David et al., let me know if you still > see the crashes with this applied. > > Of course, I'll queue this up for -stable as well. > > Thanks! > > ==================== > [PATCH] sparc64: Fix several bugs in memmove(). > > Firstly, handle zero length calls properly. Believe it or not there > are a few of these happening during early boot. > > Next, we can't just drop to a memcpy() call in the forward copy case > where dst <= src. The reason is that the cache initializing stores > used in the Niagara memcpy() implementations can end up clearing out > cache lines before we've sourced their original contents completely. > > For example, considering NG4memcpy, the main unrolled loop begins like > this: > > load src + 0x00 > load src + 0x08 > load src + 0x10 > load src + 0x18 > load src + 0x20 > store dst + 0x00 > > Assume dst is 64 byte aligned and let's say that dst is src - 8 for > this memcpy() call. That store at the end there is the one to the > first line in the cache line, thus clearing the whole line, which thus > clobbers "src + 0x28" before it even gets loaded. > > To avoid this, just fall through to a simple copy only mildly > optimized for the case where src and dst are 8 byte aligned and the > length is a multiple of 8 as well. We could get fancy and call > GENmemcpy() but this is good enough for how this thing is actually > used. > > Reported-by: David Ahern > Reported-by: Bob Picco > Signed-off-by: David S. Miller > --- Seems solid with 2.6.39 on M7-4. Jalap?no is happy with current sparc.git. -- 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