On Sat, 2021-12-11 at 22:31 +0530, Neeraj Upadhyay wrote: > When multiple CPUs in the same nocb gp/cb group concurrently > come online, they might try to concurrently create the same > rcuog kthread. Fix this by using nocb gp CPU's spawn mutex to > provide mutual exclusion for the rcuog kthread creation code. > > Signed-off-by: Neeraj Upadhyay <quic_neeraju@xxxxxxxxxxx> > --- > Change in v2: > Fix missing mutex_unlock in nocb gp kthread creation err path. I think this ends up being not strictly necessary in the short term too because we aren't currently planning to run rcutree_prepare_cpu() concurrently anyway. But harmless and worth fixing in the longer term. Although, if I've already added a mutex for adding the boost thread, could we manage to use the *same* mutex instead of adding another one? Acked-by: David Woodhouse <dwmw@xxxxxxxxxxxx> + mutex_unlock(&rdp_gp->nocb_gp_kthread_mutex); > return; > + } > WRITE_ONCE(rdp_gp->nocb_gp_kthread, t); > } > + mutex_unlock(&rdp_gp->nocb_gp_kthread_mutex); > > /* Spawn the kthread for this CPU. */ Some whitespace damage there.
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