# git rev-parse -q --verify a75a001540d03c30315e43884ad95cc68040f18d^{commit}
a75a001540d03c30315e43884ad95cc68040f18d
already have revision, skipping fetch
# git checkout -q -f -B kisskb a75a001540d03c30315e43884ad95cc68040f18d
# git clean -qxdf
# < git log -1
# commit a75a001540d03c30315e43884ad95cc68040f18d
# Author: Michael Ellerman <mpe@ellerman.id.au>
# Date:   Thu Nov 1 16:21:05 2018 +1100
# 
#     powerpc/mm/64s: Fix preempt warning in slb_allocate_kernel()
#     
#     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>
# < /opt/cross/kisskb/br-aarch64-glibc-2016.08-613-ge98b4dd/bin/aarch64-linux-gcc --version
# < git log --format=%s --max-count=1 a75a001540d03c30315e43884ad95cc68040f18d
# < make -s -j 8 ARCH=arm64 O=/kisskb/build/powerpc-fixes_arm64-defconfig_arm64 CROSS_COMPILE=/opt/cross/kisskb/br-aarch64-glibc-2016.08-613-ge98b4dd/bin/aarch64-linux-  defconfig
# make -s -j 8 ARCH=arm64 O=/kisskb/build/powerpc-fixes_arm64-defconfig_arm64 CROSS_COMPILE=/opt/cross/kisskb/br-aarch64-glibc-2016.08-613-ge98b4dd/bin/aarch64-linux-  
arch/arm64/Makefile:27: ld does not support --fix-cortex-a53-843419; kernel may be susceptible to erratum
arch/arm64/Makefile:40: LSE atomics not supported by binutils
Completed OK
# rm -rf /kisskb/build/powerpc-fixes_arm64-defconfig_arm64
# Build took: 0:05:32.803268