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| author | Phil Auld <pauld@redhat.com> | 2022-03-31 18:39:26 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-04-13 21:59:17 +0300 |
| commit | 87f5d66daa5f457449bb95d6b8d18bb7596aa627 (patch) | |
| tree | ae2c5ba8c6ac30b594b4ee534d261a27ac8a941d /arch | |
| parent | cb713eb793e6f308d91ffa2f483d2c59e6c2e3ad (diff) | |
| download | linux-87f5d66daa5f457449bb95d6b8d18bb7596aa627.tar.xz | |
arch/arm64: Fix topology initialization for core scheduling
[ Upstream commit 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: 9edeaea1bc45 ("sched: Core-wide rq->lock")
Signed-off-by: Phil Auld <pauld@redhat.com>
Reviewed-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/20220331153926.25742-1-pauld@redhat.com
Signed-off-by: Will Deacon <will@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/kernel/smp.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/arm64/kernel/smp.c b/arch/arm64/kernel/smp.c index 6f6ff072acbd..3beaa6640ab3 100644 --- a/arch/arm64/kernel/smp.c +++ b/arch/arm64/kernel/smp.c @@ -234,6 +234,7 @@ asmlinkage notrace void secondary_start_kernel(void) * Log the CPU info before it is marked online and might get read. */ cpuinfo_store_cpu(); + store_cpu_topology(cpu); /* * Enable GIC and timers. @@ -242,7 +243,6 @@ asmlinkage notrace void secondary_start_kernel(void) ipi_setup(cpu); - store_cpu_topology(cpu); numa_add_cpu(cpu); /* |