From: Marcelo Tosatti <mtosatti@redhat.com>
To: Sheng Yang <sheng@linux.intel.com>
Cc: Avi Kivity <avi@redhat.com>, kvm@vger.kernel.org
Subject: Re: [PATCH v2] KVM: Fix IOMMU RCU related warning
Date: Thu, 1 Jul 2010 13:16:22 -0300 [thread overview]
Message-ID: <20100701161622.GE23469@amt.cnet> (raw)
In-Reply-To: <1278000713-18752-1-git-send-email-sheng@linux.intel.com>
On Fri, Jul 02, 2010 at 12:11:53AM +0800, Sheng Yang wrote:
> This patch fixes the following warning.
>
> ===================================================
> [ INFO: suspicious rcu_dereference_check() usage. ]
> ---------------------------------------------------
> include/linux/kvm_host.h:259 invoked rcu_dereference_check() without
> protection!
>
> other info that might help us debug this:
>
> rcu_scheduler_active = 1, debug_locks = 0
> no locks held by qemu-system-x86/29679.
>
> stack backtrace:
> Pid: 29679, comm: qemu-system-x86 Not tainted 2.6.35-rc3+ #200
> Call Trace:
> [<ffffffff810a224e>] lockdep_rcu_dereference+0xa8/0xb1
> [<ffffffffa018a06f>] kvm_iommu_unmap_memslots+0xc9/0xde [kvm]
> [<ffffffffa018a0c4>] kvm_iommu_unmap_guest+0x40/0x4e [kvm]
> [<ffffffffa018f772>] kvm_arch_destroy_vm+0x1a/0x186 [kvm]
> [<ffffffffa01800d0>] kvm_put_kvm+0x110/0x167 [kvm]
> [<ffffffffa0180ecc>] kvm_vcpu_release+0x18/0x1c [kvm]
> [<ffffffff81156f5d>] fput+0x22a/0x3a0
> [<ffffffff81152288>] filp_close+0xb4/0xcd
> [<ffffffff8106599f>] put_files_struct+0x1b7/0x36b
> [<ffffffff81065830>] ? put_files_struct+0x48/0x36b
> [<ffffffff8131ee59>] ? do_raw_spin_unlock+0x118/0x160
> [<ffffffff81065bc0>] exit_files+0x6d/0x75
> [<ffffffff81068348>] do_exit+0x47d/0xc60
> [<ffffffff8177e7b5>] ? _raw_spin_unlock_irq+0x30/0x36
> [<ffffffff81068bfa>] do_group_exit+0xcf/0x134
> [<ffffffff81080790>] get_signal_to_deliver+0x732/0x81d
> [<ffffffff81095996>] ? cpu_clock+0x4e/0x60
> [<ffffffff81002082>] do_notify_resume+0x117/0xc43
> [<ffffffff810a2fa3>] ? trace_hardirqs_on+0xd/0xf
> [<ffffffff81080d79>] ? sys_rt_sigtimedwait+0x2b5/0x3bf
> [<ffffffff8177d9f2>] ? trace_hardirqs_off_thunk+0x3a/0x3c
> [<ffffffff81003221>] ? sysret_signal+0x5/0x3d
> [<ffffffff8100343b>] int_signal+0x12/0x17
>
> Signed-off-by: Sheng Yang <sheng@linux.intel.com>
> ---
> I just realized the first version of patch unnecessarily covered
> kvm_iommu_map_memslots(), because that part had already been
> covered by kvm_vm_ioctl_assign_device() definitely(though unpaired
> callings seems a little strange...).
Since nesting srcu_read_lock is OK, its fine to have it in
kvm_iommu_map_memslots, even if unnecessary.
prev parent reply other threads:[~2010-07-01 16:17 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-01 7:00 [PATCH] KVM: Fix IOMMU memslot reference warning Sheng Yang
2010-07-01 15:58 ` Marcelo Tosatti
2010-07-01 16:11 ` [PATCH v2] KVM: Fix IOMMU RCU related warning Sheng Yang
2010-07-01 16:16 ` Marcelo Tosatti [this message]
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