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Subject[PATCH 4.19 3/3] ia64: ensure proper NUMA distance and possible map initialization
Date
From: Valentin Schneider <valentin.schneider@arm.com>

commit b22a8f7b4bde4e4ab73b64908ffd5d90ecdcdbfd upstream.

John Paul reported a warning about bogus NUMA distance values spurred by
commit:

620a6dc40754 ("sched/topology: Make sched_init_numa() use a set for the deduplicating sort")

In this case, the afflicted machine comes up with a reported 256 possible
nodes, all of which are 0 distance away from one another. This was
previously silently ignored, but is now caught by the aforementioned
commit.

The culprit is ia64's node_possible_map which remains unchanged from its
initialization value of NODE_MASK_ALL. In John's case, the machine
doesn't have any SRAT nor SLIT table, but AIUI the possible map remains
untouched regardless of what ACPI tables end up being parsed. Thus,
!online && possible nodes remain with a bogus distance of 0 (distances \in
[0, 9] are "reserved and have no meaning" as per the ACPI spec).

Follow x86 / drivers/base/arch_numa's example and set the possible map to
the parsed map, which in this case seems to be the online map.

Link: http://lore.kernel.org/r/255d6b5d-194e-eb0e-ecdd-97477a534441@physik.fu-berlin.de
Link: https://lkml.kernel.org/r/20210318130617.896309-1-valentin.schneider@arm.com
Fixes: 620a6dc40754 ("sched/topology: Make sched_init_numa() use a set for the deduplicating sort")
Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Reported-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Tested-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Tested-by: Sergei Trofimovich <slyfox@gentoo.org>
Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Anatoly Pugachev <matorola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[ dannf: minor context adjustment in arch/ia64/kernel/acpi.c ]
Signed-off-by: dann frazier <dann.frazier@canonical.com>
---
arch/ia64/kernel/acpi.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/ia64/kernel/acpi.c b/arch/ia64/kernel/acpi.c
index 1dacbf5e9e09..3856894e86b8 100644
--- a/arch/ia64/kernel/acpi.c
+++ b/arch/ia64/kernel/acpi.c
@@ -537,7 +537,8 @@ void __init acpi_numa_fixup(void)
if (srat_num_cpus == 0) {
node_set_online(0);
node_cpuid[0].phys_id = hard_smp_processor_id();
- return;
+ slit_distance(0, 0) = LOCAL_DISTANCE;
+ goto out;
}

/*
@@ -580,7 +581,7 @@ void __init acpi_numa_fixup(void)
for (j = 0; j < MAX_NUMNODES; j++)
node_distance(i, j) = i == j ? LOCAL_DISTANCE :
REMOTE_DISTANCE;
- return;
+ goto out;
}

memset(numa_slit, -1, sizeof(numa_slit));
@@ -605,6 +606,8 @@ void __init acpi_numa_fixup(void)
printk("\n");
}
#endif
+out:
+ node_possible_map = node_online_map;
}
#endif /* CONFIG_ACPI_NUMA */

--
2.25.1
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