linux-kernel - Re: [PATCH v4 08/10] powerpc/smp: Allocate cpumask only after searching thread group

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Date:   Fri, 31 Jul 2020 17:52:15 +1000
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:     linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>,
        Srikar Dronamraju <srikar@...ux.vnet.ibm.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Anton Blanchard <anton@...abs.org>,
        Oliver O'Halloran <oohall@...il.com>,
        Nathan Lynch <nathanl@...ux.ibm.com>,
        Michael Neuling <mikey@...ling.org>,
        Gautham R Shenoy <ego@...ux.vnet.ibm.com>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Valentin Schneider <valentin.schneider@....com>,
        Jordan Niethe <jniethe5@...il.com>
Subject: Re: [PATCH v4 08/10] powerpc/smp: Allocate cpumask only after searching thread group

Srikar Dronamraju <srikar@...ux.vnet.ibm.com> writes:
> If allocated earlier and the search fails, then cpumask need to be
> freed. However cpu_l1_cache_map can be allocated after we search thread
> group.

It's not freed anywhere AFAICS?

And even after this change there's still an error path that doesn't free
it, isn't there?

cheers

> Cc: linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>
> Cc: LKML <linux-kernel@...r.kernel.org>
> Cc: Michael Ellerman <mpe@...erman.id.au>
> Cc: Nicholas Piggin <npiggin@...il.com>
> Cc: Anton Blanchard <anton@...abs.org>
> Cc: Oliver O'Halloran <oohall@...il.com>
> Cc: Nathan Lynch <nathanl@...ux.ibm.com>
> Cc: Michael Neuling <mikey@...ling.org>
> Cc: Gautham R Shenoy <ego@...ux.vnet.ibm.com>
> Cc: Ingo Molnar <mingo@...nel.org>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Cc: Valentin Schneider <valentin.schneider@....com>
> Cc: Jordan Niethe <jniethe5@...il.com>
> Reviewed-by: Gautham R. Shenoy <ego@...ux.vnet.ibm.com>
> Signed-off-by: Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
> ---
>  arch/powerpc/kernel/smp.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> index 698000c7f76f..dab96a1203ec 100644
> --- a/arch/powerpc/kernel/smp.c
> +++ b/arch/powerpc/kernel/smp.c
> @@ -797,10 +797,6 @@ static int init_cpu_l1_cache_map(int cpu)
>  	if (err)
>  		goto out;
>  
> -	zalloc_cpumask_var_node(&per_cpu(cpu_l1_cache_map, cpu),
> -				GFP_KERNEL,
> -				cpu_to_node(cpu));
> -
>  	cpu_group_start = get_cpu_thread_group_start(cpu, &tg);
>  
>  	if (unlikely(cpu_group_start == -1)) {
> @@ -809,6 +805,9 @@ static int init_cpu_l1_cache_map(int cpu)
>  		goto out;
>  	}
>  
> +	zalloc_cpumask_var_node(&per_cpu(cpu_l1_cache_map, cpu),
> +				GFP_KERNEL, cpu_to_node(cpu));
> +
>  	for (i = first_thread; i < first_thread + threads_per_core; i++) {
>  		int i_group_start = get_cpu_thread_group_start(i, &tg);
>  
> -- 
> 2.17.1