Re: [PATCH] KVM: arm64: Select SCHED_INFO before SCHEDSTATS

From: Marc Zyngier
Date: Wed Oct 23 2019 - 12:51:25 EST


On 2019-10-23 04:22, Mao Wenan wrote:
If KVM=y, it will select SCHEDSTATS, below erros can
be seen:
kernel/sched/stats.h: In function rq_sched_info_arrive:
kernel/sched/stats.h:12:20: error: struct sched_info
has no member named run_delay
rq->rq_sched_info.run_delay += delta;
^
kernel/sched/stats.h:13:20: error: struct sched_info
has no member named pcount
rq->rq_sched_info.pcount++;
^
kernel/sched/stats.h: In function rq_sched_info_dequeued:
kernel/sched/stats.h:31:20: error: struct sched_info has
no member named run_delay
rq->rq_sched_info.run_delay += delta;

These are because CONFIG_SCHED_INFO is not set, This patch
is to select SCHED_INFO before SCHEDSTATS.

Fixes: 8564d6372a7d ("KVM: arm64: Support stolen time reporting via
shared structure")
Signed-off-by: Mao Wenan <maowenan@xxxxxxxxxx>
---
arch/arm64/kvm/Kconfig | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
index d8b88e4..3c46eac 100644
--- a/arch/arm64/kvm/Kconfig
+++ b/arch/arm64/kvm/Kconfig
@@ -39,6 +39,7 @@ config KVM
select IRQ_BYPASS_MANAGER
select HAVE_KVM_IRQ_BYPASS
select HAVE_KVM_VCPU_RUN_PID_CHANGE
+ select SCHED_INFO
select SCHEDSTATS
---help---
Support hosting virtualized guest machines.

SCHEDSTATS is really an odd choice. Here's what I get after disabling
DEBUG_KERNEL (from defconfig):

WARNING: unmet direct dependencies detected for SCHEDSTATS
Depends on [n]: DEBUG_KERNEL [=n] && PROC_FS [=y]
Selected by [y]:
- KVM [=y] && VIRTUALIZATION [=y] && OF [=y]

WARNING: unmet direct dependencies detected for SCHEDSTATS
Depends on [n]: DEBUG_KERNEL [=n] && PROC_FS [=y]
Selected by [y]:
- KVM [=y] && VIRTUALIZATION [=y] && OF [=y]

WARNING: unmet direct dependencies detected for SCHEDSTATS
Depends on [n]: DEBUG_KERNEL [=n] && PROC_FS [=y]
Selected by [y]:
- KVM [=y] && VIRTUALIZATION [=y] && OF [=y]

So clearly SCHEDSTATS isn't meant to be selected on its own.

We can either just select SCHED_INFO (which *nobody else does*), or go
the full x86 way which selects TASK_DELAY_ACCT (and thus depends on
NET && MULTIUSER). My gut feeling is that we shouldn't deviate too much
from x86...

Thoughts?

M.
--
Jazz is not dead. It just smells funny...