58 lines
2.0 KiB
Diff
58 lines
2.0 KiB
Diff
From ce6105c1e1149f6a8272acf267011edcf92ba778 Mon Sep 17 00:00:00 2001
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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Thu, 12 Dec 2019 10:53:59 +0100
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Subject: [PATCH 318/319] sched: migrate_enable: Busy loop until the migration
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request is completed
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/4.19/older/patches-4.19.103-rt42.tar.xz
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[ Upstream commit 140d7f54a5fff02898d2ca9802b39548bf7455f1 ]
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If user task changes the CPU affinity mask of a running task it will
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dispatch migration request if the current CPU is no longer allowed. This
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might happen shortly before a task enters a migrate_disable() section.
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Upon leaving the migrate_disable() section, the task will notice that
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the current CPU is no longer allowed and will will dispatch its own
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migration request to move it off the current CPU.
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While invoking __schedule() the first migration request will be
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processed and the task returns on the "new" CPU with "arg.done = 0". Its
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own migration request will be processed shortly after and will result in
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memory corruption if the stack memory, designed for request, was used
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otherwise in the meantime.
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Spin until the migration request has been processed if it was accepted.
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
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---
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kernel/sched/core.c | 7 +++++--
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1 file changed, 5 insertions(+), 2 deletions(-)
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diff --git a/kernel/sched/core.c b/kernel/sched/core.c
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index cbd76324babd..4616c086dd26 100644
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--- a/kernel/sched/core.c
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+++ b/kernel/sched/core.c
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@@ -7329,7 +7329,7 @@ void migrate_enable(void)
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WARN_ON(smp_processor_id() != cpu);
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if (!is_cpu_allowed(p, cpu)) {
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- struct migration_arg arg = { p };
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+ struct migration_arg arg = { .task = p };
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struct cpu_stop_work work;
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struct rq_flags rf;
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@@ -7342,7 +7342,10 @@ void migrate_enable(void)
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&arg, &work);
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tlb_migrate_finish(p->mm);
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__schedule(true);
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- WARN_ON_ONCE(!arg.done && !work.disabled);
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+ if (!work.disabled) {
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+ while (!arg.done)
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+ cpu_relax();
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+ }
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}
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out:
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--
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2.25.0
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