c8b00bb742
With preempt enabled we see warnings in do_slb_fault(): BUG: using smp_processor_id() in preemptible [00000000] code: kworker/u33:0/98 futex hash table entries: 4096 (order: 3, 524288 bytes) caller is do_slb_fault+0x204/0x230 CPU: 5 PID: 98 Comm: kworker/u33:0 Not tainted 4.19.0-rc3-gcc-7.3.1-00022-g1936f094e164 #138 Call Trace: dump_stack+0xb4/0x104 (unreliable) check_preemption_disabled+0x148/0x150 do_slb_fault+0x204/0x230 data_access_slb_common+0x138/0x180 This is caused by the get_paca() in slb_allocate_kernel(), which includes a call to debug_smp_processor_id(). slb_allocate_kernel() can only be called from do_slb_fault(), and in that path interrupts are hard disabled and so we can't be preempted, but we can't update the preempt flags (in thread_info) because that could cause an SLB fault. So just use local_paca which is safe and doesn't cause the warning. Fixes: 48e7b7695745 ("powerpc/64s/hash: Convert SLB miss handlers to C") Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
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.