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Re: [Qemu-devel] [PULL 08/21] rcu: run RCU callbacks under the BQL
From: |
Leon Alrae |
Subject: |
Re: [Qemu-devel] [PULL 08/21] rcu: run RCU callbacks under the BQL |
Date: |
Wed, 25 Feb 2015 17:16:02 +0000 |
User-agent: |
Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 |
Hi,
On 16/02/2015 18:17, Paolo Bonzini wrote:
> This needs to go away sooner or later, but one complication is the
> complex VFIO data structures that are modified in instance_finalize.
> Take a shortcut for now.
It looks like this commit introduced a race condition. QEMU segfaults
very early in one of my tests where I boot Linux, and on one of my
machines it's easier to reproduce than on the others.
(gdb) bt
#0 0x00007ffff7b09fe3 in qemu_cpu_kick_thread (cpu=0x0) at
/slave/smoketest/src/cpus.c:1045
#1 0x00007ffff7b0a269 in qemu_mutex_lock_iothread () at
/slave/smoketest/src/cpus.c:1119
#2 0x00007ffff7ec5c39 in call_rcu_thread (opaque=0x0) at
/slave/smoketest/src/util/rcu.c:241
#3 0x00007ffff38489d1 in start_thread () from /lib64/libpthread.so.0
#4 0x00007ffff359586d in clone () from /lib64/libc.so.6
qemu_mutex_lock_iothread() passes first_cpu to qemu_cpu_kick_thread().
Sometimes this is happening before executing cpu_exec_init(), which I
believe is the reason why qemu_cpu_kick_thread() receives a null pointer.
Regards,
Leon
- [Qemu-devel] [PULL 00/21] SCSI, RCU, KVM changes for 2015-02-16, Paolo Bonzini, 2015/02/16
- [Qemu-devel] [PULL 02/21] qdev: support to get a device firmware path directly, Paolo Bonzini, 2015/02/16
- [Qemu-devel] [PULL 03/21] vhost-scsi: add bootindex property, Paolo Bonzini, 2015/02/16
- [Qemu-devel] [PULL 04/21] vhost-scsi: expose the TYPE_FW_PATH_PROVIDER interface, Paolo Bonzini, 2015/02/16
- [Qemu-devel] [PULL 06/21] vhost-scsi: set the bootable value of channel/target/lun, Paolo Bonzini, 2015/02/16
- [Qemu-devel] [PULL 07/21] rcu: do not let RCU callbacks pile up indefinitely, Paolo Bonzini, 2015/02/16
- [Qemu-devel] [PULL 05/21] vhost-scsi: add a property for booting, Paolo Bonzini, 2015/02/16
- [Qemu-devel] [PULL 01/21] kvm_stat: Add kvm_exit reasons for aarch64, Paolo Bonzini, 2015/02/16
- [Qemu-devel] [PULL 08/21] rcu: run RCU callbacks under the BQL, Paolo Bonzini, 2015/02/16
- Re: [Qemu-devel] [PULL 08/21] rcu: run RCU callbacks under the BQL,
Leon Alrae <=
[Qemu-devel] [PULL 10/21] pcie: remove mmconfig memory leak and wrap mmconfig update with transaction, Paolo Bonzini, 2015/02/16
[Qemu-devel] [PULL 11/21] pci: split shpc_cleanup and shpc_free, Paolo Bonzini, 2015/02/16
[Qemu-devel] [PULL 12/21] docs: clarify memory region lifecycle, Paolo Bonzini, 2015/02/16
[Qemu-devel] [PULL 14/21] exec: make iotlb RCU-friendly, Paolo Bonzini, 2015/02/16
[Qemu-devel] [PULL 15/21] exec: RCUify AddressSpaceDispatch, Paolo Bonzini, 2015/02/16
[Qemu-devel] [PULL 09/21] memory: keep the owner of the AddressSpace alive until do_address_space_destroy, Paolo Bonzini, 2015/02/16