Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. 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.
Wanpeng Li
authored
WARNING: CPU: 5 PID: 1242 at kernel/rcu/tree_plugin.h:323 rcu_note_context_switch+0x207/0x6b0 CPU: 5 PID: 1242 Comm: unity-settings- Not tainted 4.13.0-rc2+ #1 RIP: 0010:rcu_note_context_switch+0x207/0x6b0 Call Trace: __schedule+0xda/0xba0 ? kvm_async_pf_task_wait+0x1b2/0x270 schedule+0x40/0x90 kvm_async_pf_task_wait+0x1cc/0x270 ? prepare_to_swait+0x22/0x70 do_async_page_fault+0x77/0xb0 ? do_async_page_fault+0x77/0xb0 async_page_fault+0x28/0x30 RIP: 0010:__d_lookup_rcu+0x90/0x1e0 I encounter this when trying to stress the async page fault in L1 guest w/ L2 guests running. Commit 9b132fbe (Add rcu user eqs exception hooks for async page fault) adds rcu_irq_enter/exit() to kvm_async_pf_task_wait() to exit cpu idle eqs when needed, to protect the code that needs use rcu. However, we need to call the pair even if the function calls schedule(), as seen from the above backtrace. This patch fixes it by informing the RCU subsystem exit/enter the irq towards/away from idle for both n.halted and !n.halted. Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: stable@vger.kernel.org Signed-off-by:Wanpeng Li <wanpeng.li@hotmail.com> Reviewed-by:
Paolo Bonzini <pbonzini@redhat.com> Signed-off-by:
Radim Krčmář <rkrcmar@redhat.com>