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SubjectRe: [PATCH 1/2] mm: use kvzalloc for swap_info_struct allocation
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Vasily Averin <vvs@virtuozzo.com> writes:

> commit a2468cc9bfdf ("swap: choose swap device according to numa node")
> increased size of swap_info_struct up to 44 Kbytes, now it requires
> 4th order page.

Why swap_info_struct could be so large? Because MAX_NUMNODES could be
thousands so that 'avail_lists' field could be tens KB? If so, I think
it's fair to use kvzalloc(). Can you add one line comment? Because
struct swap_info_struct is quite small in default configuration.

Best Regards,
Huang, Ying

> Switch to kvzmalloc allows to avoid unexpected allocation failures.
>
> Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
> ---
> mm/swapfile.c | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/mm/swapfile.c b/mm/swapfile.c
> index 644f746e167a..8688ae65ef58 100644
> --- a/mm/swapfile.c
> +++ b/mm/swapfile.c
> @@ -2813,7 +2813,7 @@ static struct swap_info_struct *alloc_swap_info(void)
> unsigned int type;
> int i;
>
> - p = kzalloc(sizeof(*p), GFP_KERNEL);
> + p = kvzalloc(sizeof(*p), GFP_KERNEL);
> if (!p)
> return ERR_PTR(-ENOMEM);
>
> @@ -2824,7 +2824,7 @@ static struct swap_info_struct *alloc_swap_info(void)
> }
> if (type >= MAX_SWAPFILES) {
> spin_unlock(&swap_lock);
> - kfree(p);
> + kvfree(p);
> return ERR_PTR(-EPERM);
> }
> if (type >= nr_swapfiles) {
> @@ -2838,7 +2838,7 @@ static struct swap_info_struct *alloc_swap_info(void)
> smp_wmb();
> nr_swapfiles++;
> } else {
> - kfree(p);
> + kvfree(p);
> p = swap_info[type];
> /*
> * Do not memset this entry: a racing procfs swap_next()

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