From: Paul Mackerras <paulus@ozlabs.org>
To: Qian Cai <cai@lca.pw>
Cc: mpe@ellerman.id.au, benh@kernel.crashing.org, aik@ozlabs.ru,
paulmck@kernel.org, linuxppc-dev@lists.ozlabs.org,
kvm-ppc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] powerpc/kvm/book3s64/vio: fix some RCU-list locks
Date: Wed, 27 May 2020 14:19:22 +1000 [thread overview]
Message-ID: <20200527041922.GE293451@thinks.paulus.ozlabs.org> (raw)
In-Reply-To: <20200510051834.2011-1-cai@lca.pw>
On Sun, May 10, 2020 at 01:18:34AM -0400, Qian Cai wrote:
> It is unsafe to traverse kvm->arch.spapr_tce_tables and
> stt->iommu_tables without the RCU read lock held. Also, add
> cond_resched_rcu() in places with the RCU read lock held that could take
> a while to finish.
>
> arch/powerpc/kvm/book3s_64_vio.c:76 RCU-list traversed in non-reader section!!
>
> other info that might help us debug this:
>
> rcu_scheduler_active = 2, debug_locks = 1
> no locks held by qemu-kvm/4265.
>
> stack backtrace:
> CPU: 96 PID: 4265 Comm: qemu-kvm Not tainted 5.7.0-rc4-next-20200508+ #2
> Call Trace:
> [c000201a8690f720] [c000000000715948] dump_stack+0xfc/0x174 (unreliable)
> [c000201a8690f770] [c0000000001d9470] lockdep_rcu_suspicious+0x140/0x164
> [c000201a8690f7f0] [c008000010b9fb48] kvm_spapr_tce_release_iommu_group+0x1f0/0x220 [kvm]
> [c000201a8690f870] [c008000010b8462c] kvm_spapr_tce_release_vfio_group+0x54/0xb0 [kvm]
> [c000201a8690f8a0] [c008000010b84710] kvm_vfio_destroy+0x88/0x140 [kvm]
> [c000201a8690f8f0] [c008000010b7d488] kvm_put_kvm+0x370/0x600 [kvm]
> [c000201a8690f990] [c008000010b7e3c0] kvm_vm_release+0x38/0x60 [kvm]
> [c000201a8690f9c0] [c0000000005223f4] __fput+0x124/0x330
> [c000201a8690fa20] [c000000000151cd8] task_work_run+0xb8/0x130
> [c000201a8690fa70] [c0000000001197e8] do_exit+0x4e8/0xfa0
> [c000201a8690fb70] [c00000000011a374] do_group_exit+0x64/0xd0
> [c000201a8690fbb0] [c000000000132c90] get_signal+0x1f0/0x1200
> [c000201a8690fcc0] [c000000000020690] do_notify_resume+0x130/0x3c0
> [c000201a8690fda0] [c000000000038d64] syscall_exit_prepare+0x1a4/0x280
> [c000201a8690fe20] [c00000000000c8f8] system_call_common+0xf8/0x278
>
> ====
> arch/powerpc/kvm/book3s_64_vio.c:368 RCU-list traversed in non-reader section!!
>
> other info that might help us debug this:
>
> rcu_scheduler_active = 2, debug_locks = 1
> 2 locks held by qemu-kvm/4264:
> #0: c000201ae2d000d8 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0xdc/0x950 [kvm]
> #1: c000200c9ed0c468 (&kvm->srcu){....}-{0:0}, at: kvmppc_h_put_tce+0x88/0x340 [kvm]
>
> ====
> arch/powerpc/kvm/book3s_64_vio.c:108 RCU-list traversed in non-reader section!!
>
> other info that might help us debug this:
>
> rcu_scheduler_active = 2, debug_locks = 1
> 1 lock held by qemu-kvm/4257:
> #0: c000200b1b363a40 (&kv->lock){+.+.}-{3:3}, at: kvm_vfio_set_attr+0x598/0x6c0 [kvm]
>
> ====
> arch/powerpc/kvm/book3s_64_vio.c:146 RCU-list traversed in non-reader section!!
>
> other info that might help us debug this:
>
> rcu_scheduler_active = 2, debug_locks = 1
> 1 lock held by qemu-kvm/4257:
> #0: c000200b1b363a40 (&kv->lock){+.+.}-{3:3}, at: kvm_vfio_set_attr+0x598/0x6c0 [kvm]
>
> Signed-off-by: Qian Cai <cai@lca.pw>
Thanks, applied to my kvm-ppc-next branch, with the cond_resched_rcu()
in kvmppc_tce_validate removed.
Paul.
WARNING: multiple messages have this Message-ID (diff)
From: Paul Mackerras <paulus@ozlabs.org>
To: Qian Cai <cai@lca.pw>
Cc: paulmck@kernel.org, aik@ozlabs.ru, linux-kernel@vger.kernel.org,
kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc/kvm/book3s64/vio: fix some RCU-list locks
Date: Wed, 27 May 2020 14:19:22 +1000 [thread overview]
Message-ID: <20200527041922.GE293451@thinks.paulus.ozlabs.org> (raw)
In-Reply-To: <20200510051834.2011-1-cai@lca.pw>
On Sun, May 10, 2020 at 01:18:34AM -0400, Qian Cai wrote:
> It is unsafe to traverse kvm->arch.spapr_tce_tables and
> stt->iommu_tables without the RCU read lock held. Also, add
> cond_resched_rcu() in places with the RCU read lock held that could take
> a while to finish.
>
> arch/powerpc/kvm/book3s_64_vio.c:76 RCU-list traversed in non-reader section!!
>
> other info that might help us debug this:
>
> rcu_scheduler_active = 2, debug_locks = 1
> no locks held by qemu-kvm/4265.
>
> stack backtrace:
> CPU: 96 PID: 4265 Comm: qemu-kvm Not tainted 5.7.0-rc4-next-20200508+ #2
> Call Trace:
> [c000201a8690f720] [c000000000715948] dump_stack+0xfc/0x174 (unreliable)
> [c000201a8690f770] [c0000000001d9470] lockdep_rcu_suspicious+0x140/0x164
> [c000201a8690f7f0] [c008000010b9fb48] kvm_spapr_tce_release_iommu_group+0x1f0/0x220 [kvm]
> [c000201a8690f870] [c008000010b8462c] kvm_spapr_tce_release_vfio_group+0x54/0xb0 [kvm]
> [c000201a8690f8a0] [c008000010b84710] kvm_vfio_destroy+0x88/0x140 [kvm]
> [c000201a8690f8f0] [c008000010b7d488] kvm_put_kvm+0x370/0x600 [kvm]
> [c000201a8690f990] [c008000010b7e3c0] kvm_vm_release+0x38/0x60 [kvm]
> [c000201a8690f9c0] [c0000000005223f4] __fput+0x124/0x330
> [c000201a8690fa20] [c000000000151cd8] task_work_run+0xb8/0x130
> [c000201a8690fa70] [c0000000001197e8] do_exit+0x4e8/0xfa0
> [c000201a8690fb70] [c00000000011a374] do_group_exit+0x64/0xd0
> [c000201a8690fbb0] [c000000000132c90] get_signal+0x1f0/0x1200
> [c000201a8690fcc0] [c000000000020690] do_notify_resume+0x130/0x3c0
> [c000201a8690fda0] [c000000000038d64] syscall_exit_prepare+0x1a4/0x280
> [c000201a8690fe20] [c00000000000c8f8] system_call_common+0xf8/0x278
>
> ====
> arch/powerpc/kvm/book3s_64_vio.c:368 RCU-list traversed in non-reader section!!
>
> other info that might help us debug this:
>
> rcu_scheduler_active = 2, debug_locks = 1
> 2 locks held by qemu-kvm/4264:
> #0: c000201ae2d000d8 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0xdc/0x950 [kvm]
> #1: c000200c9ed0c468 (&kvm->srcu){....}-{0:0}, at: kvmppc_h_put_tce+0x88/0x340 [kvm]
>
> ====
> arch/powerpc/kvm/book3s_64_vio.c:108 RCU-list traversed in non-reader section!!
>
> other info that might help us debug this:
>
> rcu_scheduler_active = 2, debug_locks = 1
> 1 lock held by qemu-kvm/4257:
> #0: c000200b1b363a40 (&kv->lock){+.+.}-{3:3}, at: kvm_vfio_set_attr+0x598/0x6c0 [kvm]
>
> ====
> arch/powerpc/kvm/book3s_64_vio.c:146 RCU-list traversed in non-reader section!!
>
> other info that might help us debug this:
>
> rcu_scheduler_active = 2, debug_locks = 1
> 1 lock held by qemu-kvm/4257:
> #0: c000200b1b363a40 (&kv->lock){+.+.}-{3:3}, at: kvm_vfio_set_attr+0x598/0x6c0 [kvm]
>
> Signed-off-by: Qian Cai <cai@lca.pw>
Thanks, applied to my kvm-ppc-next branch, with the cond_resched_rcu()
in kvmppc_tce_validate removed.
Paul.
WARNING: multiple messages have this Message-ID (diff)
From: Paul Mackerras <paulus@ozlabs.org>
To: Qian Cai <cai@lca.pw>
Cc: mpe@ellerman.id.au, benh@kernel.crashing.org, aik@ozlabs.ru,
paulmck@kernel.org, linuxppc-dev@lists.ozlabs.org,
kvm-ppc@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] powerpc/kvm/book3s64/vio: fix some RCU-list locks
Date: Wed, 27 May 2020 04:19:22 +0000 [thread overview]
Message-ID: <20200527041922.GE293451@thinks.paulus.ozlabs.org> (raw)
In-Reply-To: <20200510051834.2011-1-cai@lca.pw>
On Sun, May 10, 2020 at 01:18:34AM -0400, Qian Cai wrote:
> It is unsafe to traverse kvm->arch.spapr_tce_tables and
> stt->iommu_tables without the RCU read lock held. Also, add
> cond_resched_rcu() in places with the RCU read lock held that could take
> a while to finish.
>
> arch/powerpc/kvm/book3s_64_vio.c:76 RCU-list traversed in non-reader section!!
>
> other info that might help us debug this:
>
> rcu_scheduler_active = 2, debug_locks = 1
> no locks held by qemu-kvm/4265.
>
> stack backtrace:
> CPU: 96 PID: 4265 Comm: qemu-kvm Not tainted 5.7.0-rc4-next-20200508+ #2
> Call Trace:
> [c000201a8690f720] [c000000000715948] dump_stack+0xfc/0x174 (unreliable)
> [c000201a8690f770] [c0000000001d9470] lockdep_rcu_suspicious+0x140/0x164
> [c000201a8690f7f0] [c008000010b9fb48] kvm_spapr_tce_release_iommu_group+0x1f0/0x220 [kvm]
> [c000201a8690f870] [c008000010b8462c] kvm_spapr_tce_release_vfio_group+0x54/0xb0 [kvm]
> [c000201a8690f8a0] [c008000010b84710] kvm_vfio_destroy+0x88/0x140 [kvm]
> [c000201a8690f8f0] [c008000010b7d488] kvm_put_kvm+0x370/0x600 [kvm]
> [c000201a8690f990] [c008000010b7e3c0] kvm_vm_release+0x38/0x60 [kvm]
> [c000201a8690f9c0] [c0000000005223f4] __fput+0x124/0x330
> [c000201a8690fa20] [c000000000151cd8] task_work_run+0xb8/0x130
> [c000201a8690fa70] [c0000000001197e8] do_exit+0x4e8/0xfa0
> [c000201a8690fb70] [c00000000011a374] do_group_exit+0x64/0xd0
> [c000201a8690fbb0] [c000000000132c90] get_signal+0x1f0/0x1200
> [c000201a8690fcc0] [c000000000020690] do_notify_resume+0x130/0x3c0
> [c000201a8690fda0] [c000000000038d64] syscall_exit_prepare+0x1a4/0x280
> [c000201a8690fe20] [c00000000000c8f8] system_call_common+0xf8/0x278
>
> ==
> arch/powerpc/kvm/book3s_64_vio.c:368 RCU-list traversed in non-reader section!!
>
> other info that might help us debug this:
>
> rcu_scheduler_active = 2, debug_locks = 1
> 2 locks held by qemu-kvm/4264:
> #0: c000201ae2d000d8 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0xdc/0x950 [kvm]
> #1: c000200c9ed0c468 (&kvm->srcu){....}-{0:0}, at: kvmppc_h_put_tce+0x88/0x340 [kvm]
>
> ==
> arch/powerpc/kvm/book3s_64_vio.c:108 RCU-list traversed in non-reader section!!
>
> other info that might help us debug this:
>
> rcu_scheduler_active = 2, debug_locks = 1
> 1 lock held by qemu-kvm/4257:
> #0: c000200b1b363a40 (&kv->lock){+.+.}-{3:3}, at: kvm_vfio_set_attr+0x598/0x6c0 [kvm]
>
> ==
> arch/powerpc/kvm/book3s_64_vio.c:146 RCU-list traversed in non-reader section!!
>
> other info that might help us debug this:
>
> rcu_scheduler_active = 2, debug_locks = 1
> 1 lock held by qemu-kvm/4257:
> #0: c000200b1b363a40 (&kv->lock){+.+.}-{3:3}, at: kvm_vfio_set_attr+0x598/0x6c0 [kvm]
>
> Signed-off-by: Qian Cai <cai@lca.pw>
Thanks, applied to my kvm-ppc-next branch, with the cond_resched_rcu()
in kvmppc_tce_validate removed.
Paul.
next prev parent reply other threads:[~2020-05-27 4:21 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-10 5:18 [PATCH] powerpc/kvm/book3s64/vio: fix some RCU-list locks Qian Cai
2020-05-10 5:18 ` Qian Cai
2020-05-10 5:18 ` Qian Cai
2020-05-27 1:13 ` Paul Mackerras
2020-05-27 1:13 ` Paul Mackerras
2020-05-27 1:13 ` Paul Mackerras
2020-05-27 1:22 ` Qian Cai
2020-05-27 1:22 ` Qian Cai
2020-05-27 1:22 ` Qian Cai
2020-05-27 4:19 ` Paul Mackerras [this message]
2020-05-27 4:19 ` Paul Mackerras
2020-05-27 4:19 ` Paul Mackerras
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