Buildresult: powerpc-fixes/s390-defconfig/s390x-gcc8 built on Oct 22 2021, 05:09

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Status:	OK
Date/Time:	Oct 22 2021, 05:09
Duration:	0:05:17.255009
Builder:	ka1
Revision:	powerpc/smp: do not decrement idle task preempt count in CPU offline (`787252a10d9422f3058df9a4821f389e5326c440)`
Target:	powerpc-fixes/s390-defconfig/s390x-gcc8
Branch:	powerpc-fixes
Compiler:	s390x-gcc8 (s390-linux-gcc (GCC) 8.1.0 / GNU ld (GNU Binutils) 2.30)
Config:	defconfig (download)
Log:	Download original No warnings found in log. Full Log # git rev-parse -q --verify 787252a10d9422f3058df9a4821f389e5326c440^{commit} 787252a10d9422f3058df9a4821f389e5326c440 already have revision, skipping fetch # git checkout -q -f -B kisskb 787252a10d9422f3058df9a4821f389e5326c440 # git clean -qxdf # < git log -1 # commit 787252a10d9422f3058df9a4821f389e5326c440 # 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> # Reviewed-by: Srikar Dronamraju <srikar@linux.vnet.ibm.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/korg/gcc-8.1.0-nolibc/s390-linux/bin/s390-linux-gcc --version # < /opt/cross/kisskb/korg/gcc-8.1.0-nolibc/s390-linux/bin/s390-linux-ld --version # < git log --format=%s --max-count=1 787252a10d9422f3058df9a4821f389e5326c440 # < make -s -j 48 ARCH=s390 O=/kisskb/build/powerpc-fixes_s390-defconfig_s390x-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/s390-linux/bin/s390-linux- defconfig # < make -s -j 48 ARCH=s390 O=/kisskb/build/powerpc-fixes_s390-defconfig_s390x-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/s390-linux/bin/s390-linux- help # make -s -j 48 ARCH=s390 O=/kisskb/build/powerpc-fixes_s390-defconfig_s390x-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/s390-linux/bin/s390-linux- olddefconfig # make -s -j 48 ARCH=s390 O=/kisskb/build/powerpc-fixes_s390-defconfig_s390x-gcc8 CROSS_COMPILE=/opt/cross/kisskb/korg/gcc-8.1.0-nolibc/s390-linux/bin/s390-linux- Completed OK # rm -rf /kisskb/build/powerpc-fixes_s390-defconfig_s390x-gcc8 # Build took: 0:05:17.255009

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