Buildresult: powerpc-fixes/mmu_defconfig/microblaze-gcc5 built on Oct 18 2021, 21:05

kisskb

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Status:	OK
Date/Time:	Oct 18 2021, 21:05
Duration:	0:00:57.162705
Builder:	ka2
Revision:	powerpc/smp: do not decrement idle task preempt count in CPU offline (`6c44be1b8e2d8c0161ac39d5d39ea4dff39da71c)`
Target:	powerpc-fixes/mmu_defconfig/microblaze-gcc5
Branch:	powerpc-fixes
Compiler:	microblaze-gcc5 (microblazeel-linux-gcc.br_real (Buildroot 2016.11-git-00613-ge98b4dd) 5.4.0 / GNU ld (GNU Binutils) 2.26.1)
Config:	mmu_defconfig (download)
Log:	Download original No warnings found in log. Full Log # git rev-parse -q --verify 6c44be1b8e2d8c0161ac39d5d39ea4dff39da71c^{commit} 6c44be1b8e2d8c0161ac39d5d39ea4dff39da71c already have revision, skipping fetch # git checkout -q -f -B kisskb 6c44be1b8e2d8c0161ac39d5d39ea4dff39da71c # git clean -qxdf # < git log -1 # commit 6c44be1b8e2d8c0161ac39d5d39ea4dff39da71c # Author: Nathan Lynch <nathanl@linux.ibm.com> # Date: Fri Oct 15 12:39:02 2021 -0500 # # powerpc/smp: do not decrement idle task preempt count in CPU offline # # With PREEMPT_COUNT=y, when a CPU is offlined and then onlined again, we # get: # # BUG: scheduling while atomic: swapper/1/0/0x00000000 # no locks held by swapper/1/0. # CPU: 1 PID: 0 Comm: swapper/1 Not tainted 5.15.0-rc2+ #100 # Call Trace: # dump_stack_lvl+0xac/0x108 # __schedule_bug+0xac/0xe0 # __schedule+0xcf8/0x10d0 # schedule_idle+0x3c/0x70 # do_idle+0x2d8/0x4a0 # cpu_startup_entry+0x38/0x40 # start_secondary+0x2ec/0x3a0 # start_secondary_prolog+0x10/0x14 # # This is because powerpc's arch_cpu_idle_dead() decrements the idle task's # preempt count, for reasons explained in commit a7c2bb8279d2 ("powerpc: # Re-enable preemption before cpu_die()"), specifically "start_secondary() # expects a preempt_count() of 0." # # However, since commit 2c669ef6979c ("powerpc/preempt: Don't touch the idle # task's preempt_count during hotplug") and commit f1a0a376ca0c ("sched/core: # Initialize the idle task with preemption disabled"), that justification no # longer holds. # # The idle task isn't supposed to re-enable preemption, so remove the # vestigial preempt_enable() from the CPU offline path. # # Tested with pseries and powernv in qemu, and pseries on PowerVM. # # Fixes: 2c669ef6979c ("powerpc/preempt: Don't touch the idle task's preempt_count during hotplug") # Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com> # Reviewed-by: Valentin Schneider <valentin.schneider@arm.com> # Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> # Link: https://lore.kernel.org/r/20211015173902.2278118-1-nathanl@linux.ibm.com # < /opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux-gcc --version # < /opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux-ld --version # < git log --format=%s --max-count=1 6c44be1b8e2d8c0161ac39d5d39ea4dff39da71c # < make -s -j 48 ARCH=microblaze O=/kisskb/build/powerpc-fixes_mmu_defconfig_microblaze CROSS_COMPILE=/opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux- mmu_defconfig # < make -s -j 48 ARCH=microblaze O=/kisskb/build/powerpc-fixes_mmu_defconfig_microblaze CROSS_COMPILE=/opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux- help # make -s -j 48 ARCH=microblaze O=/kisskb/build/powerpc-fixes_mmu_defconfig_microblaze CROSS_COMPILE=/opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux- olddefconfig # make -s -j 48 ARCH=microblaze O=/kisskb/build/powerpc-fixes_mmu_defconfig_microblaze CROSS_COMPILE=/opt/cross/kisskb/br-microblaze-full-2016.08-613-ge98b4dd/bin/microblazeel-linux- Kernel: arch/microblaze/boot/linux.bin is ready (#1) Completed OK # rm -rf /kisskb/build/powerpc-fixes_mmu_defconfig_microblaze # Build took: 0:00:57.162705

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