----- Original Message ----- > From: "Ewan D. Milne" <emilne@xxxxxxxxxx> > To: "Johannes Thumshirn" <jthumshirn@xxxxxxx> > Cc: dgilbert@xxxxxxxxxxxx, "Eyal Ben David" <bdeyal@xxxxxxxxx>, "Laurence Oberman" <loberman@xxxxxxxxxx>, > linux-scsi@xxxxxxxxxxxxxxx > Sent: Tuesday, November 22, 2016 1:30:07 PM > Subject: Re: SG does not ignore dxferp (direct io + mmap) > > On Tue, 2016-11-22 at 09:37 +0100, Johannes Thumshirn wrote: > > On Mon, Nov 21, 2016 at 01:24:02PM -0500, Ewan Milne wrote: > > > On Mon, 2016-11-21 at 12:34 -0500, Douglas Gilbert wrote: > > > > There was also this change which seems closer to the problem area: > > > > > > > > commit 461c7fa126794157484dca48e88effa4963e3af3 > > > > Author: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> > > > > Date: Tue Feb 2 16:57:35 2016 -0800 > > > > > > > > drivers/scsi/sg.c: mark VMA as VM_IO to prevent migration > > > > ... > > > > > > > > diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c > > > > index 503ab8b..5e82067 100644 > > > > --- a/drivers/scsi/sg.c > > > > +++ b/drivers/scsi/sg.c > > > > @@ -1261,7 +1261,7 @@ sg_mmap(struct file *filp, struct vm_area_struct > > > > *vma) > > > > } > > > > > > > > sfp->mmap_called = 1; > > > > - vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP; > > > > + vma->vm_flags |= VM_IO | VM_DONTEXPAND | VM_DONTDUMP; > > > > vma->vm_private_data = sfp; > > > > vma->vm_ops = &sg_mmap_vm_ops; > > > > return 0; > > > > > > > > Doug Gilbert > > > > > > > > > > Neither this change nor "sg: fix dxferp in from_to case" appears to > > > fix the issue when applied on top of 4.4. Still looking... > > > > This brings bad memories from commit 2d99b55d3 back to live, but this is > > applied on all test kernels I have. > > > > I too will run some bisection as well now that we have an easy reproducer > > and > > my timezone is somewhat ahead. Let's see if we can stretch the workday a > > bit. > > I see the behavior (zero byte) on the 4.4.34, 4.5.7, 4.6.7, and 4.7.10 > -stable kernels. But not (of course) on 4.8.10 -stable. > > It doesn't look like the sg driver, might be something in the mmap code? > > -Ewan > > > > > > I have just re-installed my system here with a much larger /boot partition in preparation for the bisect builds. My prior /boot was too small to hold multiple upstream kernels during the bisect. I expect to have time Friday to Monday to do the bisects and hopefully narrow it down to what mmap code changes affect us here. I will narrow the bisect starting with and 4.7.10 bad and 4.8.10 good. 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
