arch/arm64: Fix topology initialization for core scheduling
mainline inclusion from mainline-v5.18-rc2 commit 5524cbb1 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I5OOWG CVE: NA Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5524cbb1bfcdff0cad0aaa9f94e6092002a07259 -------------------------------------------------------------------------- Arm64 systems rely on store_cpu_topology() to call update_siblings_masks() to transfer the toplogy to the various cpu masks. This needs to be done before the call to notify_cpu_starting() which tells the scheduler about each cpu found, otherwise the core scheduling data structures are setup in a way that does not match the actual topology. With smt_mask not setup correctly we bail on `cpumask_weight(smt_mask) == 1` for !leaders in: notify_cpu_starting() cpuhp_invoke_callback_range() sched_cpu_starting() sched_core_cpu_starting() which leads to rq->core not being correctly set for !leader-rq's. Without this change stress-ng (which enables core scheduling in its prctl tests in newer versions -- i.e. with PR_SCHED_CORE support) causes a warning and then a crash (trimmed for legibility): [ 1853.805168] ------------[ cut here ]------------ [ 1853.809784] task_rq(b)->core != rq->core [ 1853.809792] WARNING: CPU: 117 PID: 0 at kernel/sched/fair.c:11102 cfs_prio_less+0x1b4/0x1c4 ... [ 1854.015210] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000010 ... [ 1854.231256] Call trace: [ 1854.233689] pick_next_task+0x3dc/0x81c [ 1854.237512] __schedule+0x10c/0x4cc [ 1854.240988] schedule_idle+0x34/0x54 Fixes: 9edeaea1 ("sched: Core-wide rq->lock") Signed-off-by: NPhil Auld <pauld@redhat.com> Reviewed-by: NDietmar Eggemann <dietmar.eggemann@arm.com> Tested-by: NDietmar Eggemann <dietmar.eggemann@arm.com> Link: https://lore.kernel.org/r/20220331153926.25742-1-pauld@redhat.comSigned-off-by: NWill Deacon <will@kernel.org> Signed-off-by: NLin Shengwang <linshengwang1@huawei.com> Reviewed-by: Nlihua <hucool.lihua@huawei.com> Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
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