Re: linux-next: Tree for Aug 1

From: Guenter Roeck
Date: Wed Aug 01 2018 - 20:13:39 EST


On 08/01/2018 04:57 PM, Ming Lei wrote:
On Thu, Aug 2, 2018 at 7:47 AM, Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
On Wed, Aug 01, 2018 at 03:52:45PM -0700, James Bottomley wrote:
On Wed, 2018-08-01 at 15:48 -0700, Guenter Roeck wrote:
On Wed, Aug 01, 2018 at 05:58:52PM +1000, Stephen Rothwell wrote:
Hi all,

Changes since 20180731:

The pci tree gained a conflict against the pci-current tree.

The net-next tree gained a conflict against the bpf tree.

The block tree lost its build failure.

The staging tree still had its build failure due to an interaction
with
the vfs tree for which I disabled CONFIG_EROFS_FS.

The kspp tree lost its build failure.

Non-merge commits (relative to Linus' tree): 10070
9137 files changed, 417605 insertions(+), 179996 deletions(-)

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The widespread kernel hang issues are still seen. I managed
to bisect it after working around the transient build failures.
Bisect log is attached below. Unfortunately, it doesn't help much.
The culprit is reported as:

2d542828c5e9 Merge remote-tracking branch 'scsi/for-next'

The preceding merge,

453f1d821165 Merge remote-tracking branch 'cgroup/for-next'

checks out fine, as does the tip of scsi-next (commit 103c7b7e0184,
"Merge branch 'misc' into for-next"). No idea how to proceed.

This sounds like you may have a problem with this patch:

commit d5038a13eca72fb216c07eb717169092e92284f1
Author: Johannes Thumshirn <jthumshirn@xxxxxxx>
Date: Wed Jul 4 10:53:56 2018 +0200

scsi: core: switch to scsi-mq by default

To verify, boot with the additional kernel parameter

scsi_mod.use_blk_mq=0

Which will reverse the effect of the above patch.

Yes, that fixes the problem.

That may not the root cause, given this issue is only started to
see from next-20180731, but d5038a13eca7 (scsi: core: switch to
scsi-mq by default)
has been in -next for quite a while.

Seems something new causes this issue.


Agreed. I should have said "fixes the symptom". I'll try to bisect
with scsi_mod.use_blk_mq=1 as suggested by James.

Guenter