----- Original Message ----- > From: "Ewan Milne" <emilne@xxxxxxxxxx> > To: "Johannes Thumshirn" <jthumshirn@xxxxxxx> > Cc: "Laurence Oberman" <loberman@xxxxxxxxxx>, "Eyal Ben David" <bdeyal@xxxxxxxxx>, dgilbert@xxxxxxxxxxxx, > linux-scsi@xxxxxxxxxxxxxxx > Sent: Friday, November 25, 2016 12:56:16 PM > Subject: Re: SG does not ignore dxferp (direct io + mmap) > > >> --- > >> > >> 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 > My 100000 loop was against an HPSA target and passed all tests. Again, all I did was patch the 4.7.9 with the 2 line changes, the rest of the patch was line breaks. I guess we need to understand when it first broke and what caused that, versus what seems to correct it. Thanks Laurence -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
