b5952f8125
It is safe to traverse mm->context.iommu_group_mem_list with either mem_list_mutex or the RCU read lock held. Silence a few RCU-list false positive warnings and fix a few missing RCU read locks. arch/powerpc/mm/book3s64/iommu_api.c:330 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/4305: #0: c000000bc3fe4d68 (&container->lock){+.+.}-{3:3}, at: tce_iommu_ioctl.part.9+0xc7c/0x1870 [vfio_iommu_spapr_tce] #1: c000000001501910 (mem_list_mutex){+.+.}-{3:3}, at: mm_iommu_get+0x50/0x190 ==== arch/powerpc/mm/book3s64/iommu_api.c:132 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/4305: #0: c000000bc3fe4d68 (&container->lock){+.+.}-{3:3}, at: tce_iommu_ioctl.part.9+0xc7c/0x1870 [vfio_iommu_spapr_tce] #1: c000000001501910 (mem_list_mutex){+.+.}-{3:3}, at: mm_iommu_do_alloc+0x120/0x5f0 ==== arch/powerpc/mm/book3s64/iommu_api.c:292 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/4312: #0: c000000ecafe23c8 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0xdc/0x950 [kvm] #1: c000000045e6c468 (&kvm->srcu){....}-{0:0}, at: kvmppc_h_put_tce+0x88/0x340 [kvm] ==== arch/powerpc/mm/book3s64/iommu_api.c:424 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/4312: #0: c000000ecafe23c8 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0xdc/0x950 [kvm] #1: c000000045e6c468 (&kvm->srcu){....}-{0:0}, at: kvmppc_h_put_tce+0x88/0x340 [kvm] Signed-off-by: Qian Cai <cai@lca.pw> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200510051559.1959-1-cai@lca.pw
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.