https://bugs.dpdk.org/show_bug.cgi?id=81
Bug ID: 81
Summary: Use of rte_memseg_contig_walk in vhost_kernel.c causes
deadlock
Product: DPDK
Version: 18.08
Hardware: All
OS: All
Status: CONFIRMED
Severity: normal
Priority: Normal
Component: vhost/virtio
Assignee: dev@dpdk.org
Reporter: sea...@gmail.com
Target Milestone: ---
Deadlock can occur when allocating memory if a virtio_user device is in use.
The execution path that causes is this is as follows:
alloc_more_mem_on_socket(...);
try_expand_heap(...);
// RW Write Lock taken here...
rte_rwlock_write_lock(&mcfg->memory_hotplug_lock);
try_expand_heap_primary(...);
eal_memalloc_mem_event_notify(...);
virtio_user_mem_event_cb(...);
vhost_kernel_ioctl(...);
prepare_vhost_memory_kernel(...);
rte_memseg_contig_walk(...);
// Attempt to take RW Read Lock here...
rte_rwlock_read_lock(&mcfg->memory_hotplug_lock);
Replacing rte_memseg_contig_walk() with rte_memseg_walk_thread_unsafe() in
prepare_vhost_memory_kernel() will remove the deadlock, but could cause issues
as prepare_vhost_memory_kernel() may also be called outside of memalloc event
notify context.
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