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bpf: report RCU QS in cpumap kthread

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BugLink: https://bugs.launchpad.net/bugs/2060097

[ Upstream commit 00bf63122459e87193ee7f1bc6161c83a525569f ]

When there are heavy load, cpumap kernel threads can be busy polling
packets from redirect queues and block out RCU tasks from reaching
quiescent states. It is insufficient to just call cond_resched() in such
context. Periodically raise a consolidated RCU QS before cond_resched
fixes the problem.

Fixes: 6710e11269 ("bpf: introduce new bpf cpu map type BPF_MAP_TYPE_CPUMAP")
Reviewed-by: Jesper Dangaard Brouer <hawk@kernel.org>
Signed-off-by: Yan Zhai <yan@cloudflare.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Jesper Dangaard Brouer <hawk@kernel.org>
Link: https://lore.kernel.org/r/c17b9f1517e19d813da3ede5ed33ee18496bb5d8.1710877680.git.yan@cloudflare.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
(cherry picked from commit eb7422b8cc196c114c05ff8a88384f6c28556156)
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>
This commit is contained in:
Yan Zhai
2024-03-19 13:44:40 -07:00
committed by Roxana Nicolescu
parent 9f683b7652
commit bbf83c7c58
1 changed files with 3 additions and 0 deletions
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kernel/bpf/cpumap.c
+3
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@@ -262,6 +262,7 @@ static int cpu_map_bpf_prog_run(struct bpf_cpu_map_entry *rcpu, void **frames,
static int cpu_map_kthread_run(void *data)
{
struct bpf_cpu_map_entry *rcpu = data;
unsigned long last_qs = jiffies;
complete(&rcpu->kthread_running);
set_current_state(TASK_INTERRUPTIBLE);
@@ -287,10 +288,12 @@ static int cpu_map_kthread_run(void *data)
if (__ptr_ring_empty(rcpu->queue)) {
schedule();
sched = 1;
last_qs = jiffies;
} else {
__set_current_state(TASK_RUNNING);
}
} else {
rcu_softirq_qs_periodic(last_qs);
sched = cond_resched();
}