From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ewan Milne Subject: Re: SG does not ignore dxferp (direct io + mmap) Date: Fri, 25 Nov 2016 12:56:16 -0500 (EST) Message-ID: <1194718949.74785.1480096576577.JavaMail.zimbra@redhat.com> References: <1479752642.19792.43.camel@localhost.localdomain> <20161122083759.xeifuex3xxfimuwz@linux-x5ow.site> <1479839407.28416.21.camel@localhost.localdomain> <2146476957.2165908.1479927335303.JavaMail.zimbra@redhat.com> <1479932524.28416.43.camel@localhost.localdomain> <20161125080758.5bh5jkcgvhw3xuvb@linux-x5ow.site> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: Received: from mx6-phx2.redhat.com ([209.132.183.39]:53222 "EHLO mx6-phx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755315AbcKYR41 (ORCPT ); Fri, 25 Nov 2016 12:56:27 -0500 In-Reply-To: <20161125080758.5bh5jkcgvhw3xuvb@linux-x5ow.site> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Johannes Thumshirn Cc: Laurence Oberman , Eyal Ben David , dgilbert@interlog.com, linux-scsi@vger.kernel.org >> --- >> >> In other words, this commit made the bad behavior go away in 4.8. >> Need to look at this in more detail, it doesn't appear as if this patch >> was intended to fix such a problem. >> >> -Ewan > >Are you sure it did? I can repropduce copy_to_user() errors with 4.8 as well. >Using the very same reproducer. On 4.8 it's just harder to trigger and >doesn't trigger on AHCI as fas as I can telli (maybe I just haven't hit >it hard enough). I can trigger it on QEMUs SCSI CDROM emulation and hpsa >though. I cannot however trigger this with a minimal config inside an initrd. It did for Eyal's supplied test case on my machine, but that was not an exhaustive test, and I am a little suspicious that the behavior change was due to a side-effect of the patch rather than actually fixing something. I think what we need to understand is what caused the regression in the first place, I probably should have been bisecting the original failure rather than trying to find where it started working. I was running against an internal (physical) drive. -Ewan