Re: [dpdk-dev] [PATCH] mempool: fix alignment of memzone length when populating

["Burakov, Anatoly" <anatoly.burakov@intel.com>]

On 02-May-18 9:13 PM, Olivier Matz wrote:
> When populating a mempool with the default function, if there is not
> enough virtually contiguous memory for the whole mempool, it will be
> populated with several chunks. A chunk of the maximum available length
> is requested with:
> 
>    mz = rte_memzone_reserve_aligned(..., len=0, ..., align=x)
> 
> If align is smaller than the page size, the length of the memzone may
> not be a multiple of the page size. This makes
> rte_mempool_populate_virt() to fail because it requires a page-aligned
> length. This patch forces the memzone length to be a multiple of page
> size.
> 
> The problem can be reproduced easily by allocating more than available
> memory:
>    ./build/app/testpmd -l 0,1 -- --total-num-mbufs=65536
>    ...
>    Cause: Creation of mbuf pool for socket 0 failed: Invalid argument
> 
> After the patch, the error code is correct:
>    ./build/app/testpmd -l 0,1 -- --total-num-mbufs=65536
>    ...
>    Cause: Creation of mbuf pool for socket 0 failed: Cannot allocate memory
> 
> Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
> Fixes: ba0009560c30 ("mempool: support new allocation methods")
> ---
> 
> Hi Anatoly,
> 
> Another	option to fix this issue could be to ensure that
> rte_memzone_reserve_aligned(..., len=0, ..., align=x) returns a length
> that is	multiple of page size. Something like:
> 
>          mz = rte_memzone_reserve_aligned(mz_name, 0,
>    -                       mp->socket_id, flags, align);
>    +                       mp->socket_id, flags, RTE_MAX(pg_sz, align));
> 
> Let me know if you prefer this way.
> 
> Thanks,
> Olivier
> 
> 
>   lib/librte_mempool/rte_mempool.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/lib/librte_mempool/rte_mempool.c b/lib/librte_mempool/rte_mempool.c
> index cf5d124ec..78c3e95ec 100644
> --- a/lib/librte_mempool/rte_mempool.c
> +++ b/lib/librte_mempool/rte_mempool.c
> @@ -709,7 +709,7 @@ rte_mempool_populate_default(struct rte_mempool *mp)
>   				(void *)(uintptr_t)mz);
>   		else
>   			ret = rte_mempool_populate_virt(mp, mz->addr,
> -				mz->len, pg_sz,
> +				RTE_ALIGN_FLOOR(mz->len, pg_sz), pg_sz,
>   				rte_mempool_memchunk_mz_free,
>   				(void *)(uintptr_t)mz);
>   		if (ret < 0) {
> 

Either way is OK by me.

Acked-by: Anatoly Burakov <anatoly.burakov@intel.com>

-- 
Thanks,
Anatoly