# git rev-parse -q --verify 41368abca78c7f4da59a94fbe523579c345045bc^{commit}
41368abca78c7f4da59a94fbe523579c345045bc
already have revision, skipping fetch
# git checkout -q -f -B kisskb 41368abca78c7f4da59a94fbe523579c345045bc
# git clean -qxdf
# < git log -1
# commit 41368abca78c7f4da59a94fbe523579c345045bc
# Author: Michael Ellerman <mpe@ellerman.id.au>
# Date:   Wed Jan 25 14:01:36 2023 +1100
# 
#     powerpc/imc-pmu: Revert nest_init_lock to being a mutex
#     
#     The recent commit 76d588dddc45 ("powerpc/imc-pmu: Fix use of mutex in
#     IRQs disabled section") fixed warnings (and possible deadlocks) in the
#     IMC PMU driver by converting the locking to use spinlocks.
#     
#     It also converted the init-time nest_init_lock to a spinlock, even
#     though it's not used at runtime in IRQ disabled sections or while
#     holding other spinlocks.
#     
#     This leads to warnings such as:
#     
#       BUG: sleeping function called from invalid context at include/linux/percpu-rwsem.h:49
#       in_atomic(): 1, irqs_disabled(): 0, non_block: 0, pid: 1, name: swapper/0
#       preempt_count: 1, expected: 0
#       CPU: 7 PID: 1 Comm: swapper/0 Not tainted 6.2.0-rc2-14719-gf12cd06109f4-dirty #1
#       Hardware name: Mambo,Simulated-System POWER9 0x4e1203 opal:v6.6.6 PowerNV
#       Call Trace:
#         dump_stack_lvl+0x74/0xa8 (unreliable)
#         __might_resched+0x178/0x1a0
#         __cpuhp_setup_state+0x64/0x1e0
#         init_imc_pmu+0xe48/0x1250
#         opal_imc_counters_probe+0x30c/0x6a0
#         platform_probe+0x78/0x110
#         really_probe+0x104/0x420
#         __driver_probe_device+0xb0/0x170
#         driver_probe_device+0x58/0x180
#         __driver_attach+0xd8/0x250
#         bus_for_each_dev+0xb4/0x140
#         driver_attach+0x34/0x50
#         bus_add_driver+0x1e8/0x2d0
#         driver_register+0xb4/0x1c0
#         __platform_driver_register+0x38/0x50
#         opal_imc_driver_init+0x2c/0x40
#         do_one_initcall+0x80/0x360
#         kernel_init_freeable+0x310/0x3b8
#         kernel_init+0x30/0x1a0
#         ret_from_kernel_thread+0x5c/0x64
#     
#     Fix it by converting nest_init_lock back to a mutex, so that we can call
#     sleeping functions while holding it. There is no interaction between
#     nest_init_lock and the runtime spinlocks used by the actual PMU routines.
#     
#     Fixes: 76d588dddc45 ("powerpc/imc-pmu: Fix use of mutex in IRQs disabled section")
#     Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
# < /opt/cross/kisskb/korg/gcc-12.2.0-nolibc/powerpc64-linux/bin/powerpc64-linux-gcc --version
# < /opt/cross/kisskb/korg/gcc-12.2.0-nolibc/powerpc64-linux/bin/powerpc64-linux-ld --version
# < git log --format=%s --max-count=1 41368abca78c7f4da59a94fbe523579c345045bc
# < make -s -j 32 ARCH=powerpc O=/kisskb/build/powerpc-fixes_powernv_defconfig+NO_RADIX_powerpc-gcc12 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-12.2.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  powernv_defconfig
# Added to kconfig CONFIG_PPC_RADIX_MMU=n
# < make -s -j 32 ARCH=powerpc O=/kisskb/build/powerpc-fixes_powernv_defconfig+NO_RADIX_powerpc-gcc12 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-12.2.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  help
# make -s -j 32 ARCH=powerpc O=/kisskb/build/powerpc-fixes_powernv_defconfig+NO_RADIX_powerpc-gcc12 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-12.2.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  olddefconfig
# make -s -j 32 ARCH=powerpc O=/kisskb/build/powerpc-fixes_powernv_defconfig+NO_RADIX_powerpc-gcc12 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-12.2.0-nolibc/powerpc64-linux/bin/powerpc64-linux-  
arch/powerpc/kernel/head_64.o: warning: objtool: end_first_256B(): can't find starting instruction
arch/powerpc/kernel/optprobes_head.o: warning: objtool: optprobe_template_end(): can't find starting instruction
Completed OK
# rm -rf /kisskb/build/powerpc-fixes_powernv_defconfig+NO_RADIX_powerpc-gcc12
# Build took: 0:03:09.222266