On Thu, 2018-11-01 at 05:21:05 UTC, Michael Ellerman wrote: > 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 <m...@ellerman.id.au>
Applied to powerpc fixes. https://git.kernel.org/powerpc/c/c8b00bb742dd036388f37d019dbb9d cheers