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SubjectRe: [PATCH] hv: Fix unnecessary sleeping in hv_synic_alloc
Date
Jia-Ju Bai <baijiaju1990@gmail.com> writes:

> The kzalloc function is called with GFP_ATOMIC.
> But according to driver call graph, it is not in atomic context,
> namely no spinlock is held nor in an interrupt handler.
>
> This GFP_ATOMIC is unnecessary, and replace with GFP_KERNEL.
>
> Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
> ---
> drivers/hv/hv.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/hv/hv.c b/drivers/hv/hv.c
> index 8267439..b0d025a 100644
> --- a/drivers/hv/hv.c
> +++ b/drivers/hv/hv.c
> @@ -150,7 +150,7 @@ int hv_synic_alloc(void)
> int cpu;
>
> hv_context.hv_numa_map = kzalloc(sizeof(struct cpumask) * nr_node_ids,
> - GFP_ATOMIC);
> + GFP_KERNEL);
> if (hv_context.hv_numa_map == NULL) {
> pr_err("Unable to allocate NUMA map\n");
> goto err;

Reviewed-by: Vitaly Kuznetsov <vkuznets@redhat.com>

The subject line is not very accurate: GFP_KERNEL you switch too is the
one supporting 'sleep' when there's not enough memory, not
GFP_ATOMIC so you don't actually "Fix unnecessary sleeping". I'd suggest
you use something like "hyper-v: use GFP_KERNEL for hv_context.hv_numa_map"

--
Vitaly

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