71 lines
2.7 KiB
Diff
71 lines
2.7 KiB
Diff
# Commit 4709ec82917668c2df958ef91b4f21c049c76bee
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# Date 2023-11-20 10:49:29 +0100
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# Author Juergen Gross <jgross@suse.com>
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# Committer Jan Beulich <jbeulich@suse.com>
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xen/sched: fix sched_move_domain()
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When moving a domain out of a cpupool running with the credit2
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scheduler and having multiple run-queues, the following ASSERT() can
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be observed:
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(XEN) Xen call trace:
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(XEN) [<ffff82d04023a700>] R credit2.c#csched2_unit_remove+0xe3/0xe7
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(XEN) [<ffff82d040246adb>] S sched_move_domain+0x2f3/0x5b1
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(XEN) [<ffff82d040234cf7>] S cpupool.c#cpupool_move_domain_locked+0x1d/0x3b
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(XEN) [<ffff82d040236025>] S cpupool_move_domain+0x24/0x35
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(XEN) [<ffff82d040206513>] S domain_kill+0xa5/0x116
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(XEN) [<ffff82d040232b12>] S do_domctl+0xe5f/0x1951
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(XEN) [<ffff82d0402276ba>] S timer.c#timer_lock+0x69/0x143
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(XEN) [<ffff82d0402dc71b>] S pv_hypercall+0x44e/0x4a9
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(XEN) [<ffff82d0402012b7>] S lstar_enter+0x137/0x140
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(XEN)
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(XEN)
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(XEN) ****************************************
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(XEN) Panic on CPU 1:
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(XEN) Assertion 'svc->rqd == c2rqd(sched_unit_master(unit))' failed at common/sched/credit2.c:1159
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(XEN) ****************************************
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This is happening as sched_move_domain() is setting a different cpu
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for a scheduling unit without telling the scheduler. When this unit is
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removed from the scheduler, the ASSERT() will trigger.
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In non-debug builds the result is usually a clobbered pointer, leading
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to another crash a short time later.
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Fix that by swapping the two involved actions (setting another cpu and
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removing the unit from the scheduler).
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Link: https://github.com/Dasharo/dasharo-issues/issues/488
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Fixes: 70fadc41635b ("xen/cpupool: support moving domain between cpupools with different granularity")
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Signed-off-by: Juergen Gross <jgross@suse.com>
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Reviewed-by: George Dunlap <george.dunlap@cloud.com>
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--- a/xen/common/sched/core.c
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+++ b/xen/common/sched/core.c
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@@ -732,18 +732,20 @@ int sched_move_domain(struct domain *d,
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old_domdata = d->sched_priv;
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/*
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- * Temporarily move all units to same processor to make locking
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- * easier when moving the new units to the new processors.
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+ * Remove all units from the old scheduler, and temporarily move them to
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+ * the same processor to make locking easier when moving the new units to
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+ * new processors.
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*/
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new_p = cpumask_first(d->cpupool->cpu_valid);
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for_each_sched_unit ( d, unit )
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{
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- spinlock_t *lock = unit_schedule_lock_irq(unit);
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+ spinlock_t *lock;
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+ sched_remove_unit(old_ops, unit);
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+
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+ lock = unit_schedule_lock_irq(unit);
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sched_set_res(unit, get_sched_res(new_p));
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spin_unlock_irq(lock);
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-
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- sched_remove_unit(old_ops, unit);
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}
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old_units = d->sched_unit_list;
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