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This is a repost of the RCU patch I have posted some time ago. The only change from the previous post, was to move it to a more recent version of xen-unstable (changeset 13386). I am planning to submit the following additional patches, after this one is accepted: 1) rename_find_domain.patch: Rename find_domain_by_id(...

This is a repost of the RCU patch I have posted some time ago. The only change from the previous post, was to move it to a more recent version of xen-unstable (changeset 13386). I am planning to submit the following additional patches, after this one is accepted: 1) rename_find_domain.patch: Rename find_domain_by_id(...

tree: https://kernel.googlesource.com/pub/scm/linux/kernel/git/mst/vhost.git linux-next head: 25da3c2b439666602852820e3231349085682e1a commit: 4cfd64ce2ad979cbd9a97e1500533d2f5f1355b8 [4/5] rcu: add count of outstanding callbacks config: i386-allnoconfig (attached as .config) compiler: gcc-7 (Debian 7.4.0-10) 7.4.0 reproduce: git checkout 4cfd64ce2ad979cbd9a97e1500533d2f5f1355b8 # save the attached .config to linux build tree make ARCH=i386 If you fix the issue,...

Commit 0deab087b16a ("vsock/virtio: use RCU to avoid use-after-free on the_virtio_vsock") starts to use RCU to protect 'the_virtio_vsock' pointer, but we forgot to annotate it. This patch adds the annotation to fix the following sparse errors: net/vmw_vsock/virtio_transport.c:73:17: error: incompatible types in comparison...

Commit 0deab087b16a ("vsock/virtio: use RCU to avoid use-after-free on the_virtio_vsock") starts to use RCU to protect 'the_virtio_vsock' pointer, but we forgot to annotate it. This patch adds the annotation to fix the following sparse errors: net/vmw_vsock/virtio_transport.c:73:17: error: incompatible types in comparison...

exit_idle() should be called after irq_enter(), otherwise it throws: [ 2.513020] [ INFO: suspicious RCU usage. ] [ 2.513076] 3.6.5 #1 Not tainted [ 2.513128] ------------------------------- [ 2.513183] include/linux/rcupdate.h:725 rcu_read_lock() used illegally while idle! [ 2.513271] [ 2.513271] other info that might help us debug this: [ 2.513271] [ 2.513388] [ 2.513388] RCU...

exit_idle() should be called after irq_enter(), otherwise it throws: [ 2.513020] [ INFO: suspicious RCU usage. ] [ 2.513076] 3.6.5 #1 Not tainted [ 2.513128] ------------------------------- [ 2.513183] include/linux/rcupdate.h:725 rcu_read_lock() used illegally while idle! [ 2.513271] [ 2.513271] other info that might help us debug this: [ 2.513271] [ 2.513388] [ 2.513388] RCU...

On 06/03/2014 08:48 AM, Paolo Bonzini wrote: > Il 02/06/2014 23:58, Eric Dumazet ha scritto: >> This looks dubious >> >> What about using kfree_rcu() instead ? > > It would lead to unbound allocation from userspace. > >> translate_desc() still uses rcu_read_lock(), its not clear if the mutex >> is really held. > > Yes, vhost_get_vq_desc must be called with the vq mutex held. > > The rcu_read_lock/unlock in...

On 06/03/2014 08:48 AM, Paolo Bonzini wrote: > Il 02/06/2014 23:58, Eric Dumazet ha scritto: >> This looks dubious >> >> What about using kfree_rcu() instead ? > > It would lead to unbound allocation from userspace. > >> translate_desc() still uses rcu_read_lock(), its not clear if the mutex >> is really held. > > Yes, vhost_get_vq_desc must be called with the vq mutex held. > > The rcu_read_lock/unlock in...

...to use spinlock synchronize MMU notifier with accessors >> >> Changes from V3: >> - remove the unnecessary patch >> >> Changes from V2: >> - use seqlck helper to synchronize MMU notifier with vhost worker >> >> Changes from V1: >> - try not use RCU to syncrhonize MMU notifier with vhost worker >> - set dirty pages after no readers >> - return -EAGAIN only when we find the range is overlapped with >> metadata >> >> Jason Wang (9): >> vhost: don't set uaddr for invalid address >> vhost: val...

...to use spinlock synchronize MMU notifier with accessors >> >> Changes from V3: >> - remove the unnecessary patch >> >> Changes from V2: >> - use seqlck helper to synchronize MMU notifier with vhost worker >> >> Changes from V1: >> - try not use RCU to syncrhonize MMU notifier with vhost worker >> - set dirty pages after no readers >> - return -EAGAIN only when we find the range is overlapped with >> metadata >> >> Jason Wang (9): >> vhost: don't set uaddr for invalid address >> vhost: val...

When built with rcu checks enabled, vhost triggers bogus warnings as vhost features are read without dev->mutex sometimes. Fixing it properly is not trivial as vhost.h does not know which lockdep classes it will be used under. Disable the warning by stubbing out the check for now. Signed-off-by: Michael S. Tsirkin...

When built with rcu checks enabled, vhost triggers bogus warnings as vhost features are read without dev->mutex sometimes. Fixing it properly is not trivial as vhost.h does not know which lockdep classes it will be used under. Disable the warning by stubbing out the check for now. Signed-off-by: Michael S. Tsirkin...

...ove(), so >>>>> virtio_transport_send_pkt() or vsock_transport_cancel_pkt() may still be >>>>> running, accessing the object that we are freed. >>>> Yes, that's my point. >>>> >>>> >>>>> Should I use something like RCU to prevent this issue? >>>>> >>>>> virtio_transport_send_pkt() and vsock_transport_cancel_pkt() >>>>> { >>>>> rcu_read_lock(); >>>>> vsock = rcu_dereference(the_virtio_vsock_mutex); >&g...

...ove(), so >>>>> virtio_transport_send_pkt() or vsock_transport_cancel_pkt() may still be >>>>> running, accessing the object that we are freed. >>>> Yes, that's my point. >>>> >>>> >>>>> Should I use something like RCU to prevent this issue? >>>>> >>>>> virtio_transport_send_pkt() and vsock_transport_cancel_pkt() >>>>> { >>>>> rcu_read_lock(); >>>>> vsock = rcu_dereference(the_virtio_vsock_mutex); >&g...

...ansport_send_pkt() or vsock_transport_cancel_pkt() may still be >>>>>>> running, accessing the object that we are freed. >>>>>> Yes, that's my point. >>>>>> >>>>>> >>>>>>> Should I use something like RCU to prevent this issue? >>>>>>> >>>>>>> virtio_transport_send_pkt() and vsock_transport_cancel_pkt() >>>>>>> { >>>>>>> rcu_read_lock(); >>>>>>> vsock = rcu...

On Fri, Jul 10, 2020 at 02:12:43PM +0200, Stefano Garzarella wrote: > Commit 0deab087b16a ("vsock/virtio: use RCU to avoid use-after-free > on the_virtio_vsock") starts to use RCU to protect 'the_virtio_vsock' > pointer, but we forgot to annotate it. > > This patch adds the annotation to fix the following sparse errors: > > net/vmw_vsock/virtio_transport.c:73:17: error: inc...

From: "Paul E. McKenney" <paulmck at linux.vnet.ibm.com> The sparse checking for rcu_assign_pointer() was recently upgraded to reject non-__kernel address spaces. This also rejects __rcu, which is almost always the right thing to do. However, the use in __br_mdb_del() is legitimate: They are assigning a pointer to an element from an RCU-protected list, and all elements of this li...

On 2019/8/1 ??3:30, Jason Gunthorpe wrote: > On Wed, Jul 31, 2019 at 09:28:20PM +0800, Jason Wang wrote: >> On 2019/7/31 ??8:39, Jason Gunthorpe wrote: >>> On Wed, Jul 31, 2019 at 04:46:53AM -0400, Jason Wang wrote: >>>> We used to use RCU to synchronize MMU notifier with worker. This leads >>>> calling synchronize_rcu() in invalidate_range_start(). But on a busy >>>> system, there would be many factors that may slow down the >>>> synchronize_rcu() which makes it unsuitable to be called in MMU >...

...00, Michael S. Tsirkin wrote: > > On Fri, Aug 02, 2019 at 09:46:13AM -0300, Jason Gunthorpe wrote: > > > On Fri, Aug 02, 2019 at 05:40:07PM +0800, Jason Wang wrote: > > > > > This must be a proper barrier, like a spinlock, mutex, or > > > > > synchronize_rcu. > > > > > > > > > > > > I start with synchronize_rcu() but both you and Michael raise some > > > > concern. > > > > > > I've also idly wondered if calling synchronize_rcu() under the various > > > mm locks is a deadl...