NAK: [SRU][F][PATCH 1/1] s390/qeth: use memory reserves to back RX buffers

[Krzysztof Kozlowski]

On 04/02/2022 07:47, frank.heimes at canonical.com wrote:
> From: Julian Wiedmann <jwi at linux.ibm.com>
> 
> BugLink: https://bugs.launchpad.net/bugs/1959529
> 
> Use dev_alloc_page() for backing the RX buffers with pages. This way we
> pick up __GFP_MEMALLOC.
> 
> Signed-off-by: Julian Wiedmann <jwi at linux.ibm.com>
> Signed-off-by: David S. Miller <davem at davemloft.net>
> (backported from commit 714c9108851743bb718fbc1bfb81290f12a53854)
> Signed-off-by: Alexandra Winter <wintera at linux.ibm.com>
> Signed-off-by: Frank Heimes <frank.heimes at canonical.com>
> ---
>  drivers/s390/net/qeth_core_main.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/s390/net/qeth_core_main.c b/drivers/s390/net/qeth_core_main.c
> index ec8c7a640d9e..61372e5c279b 100644
> --- a/drivers/s390/net/qeth_core_main.c
> +++ b/drivers/s390/net/qeth_core_main.c
> @@ -227,7 +227,7 @@ static int qeth_alloc_buffer_pool(struct qeth_card *card)
>  			return -ENOMEM;
>  		}
>  		for (j = 0; j < QETH_MAX_BUFFER_ELEMENTS(card); ++j) {
> -			ptr = (void *) __get_free_page(GFP_KERNEL);
> +			ptr = (void *) __dev_alloc_page(GFP_KERNEL);

This does not look correct. New API returns "struct page*", previous
returns mapped page address. These are not the same.

Either we need to backport f81649dfa5343eef7e579eb6f8dd8bd6d300ec31
first or a page_address dance like:

struct page *page = __dev_alloc_page(GFP_KERNEL);
if (!page)
	// handle -ENOMEM
ptr = page_address(page);


>  			if (!ptr) {
>  				while (j > 0)
>  					free_page((unsigned long)
> @@ -2612,7 +2612,7 @@ static struct qeth_buffer_pool_entry *qeth_find_free_buffer_pool_entry(
>  			struct qeth_buffer_pool_entry, list);
>  	for (i = 0; i < QETH_MAX_BUFFER_ELEMENTS(card); ++i) {
>  		if (page_count(virt_to_page(entry->elements[i])) > 1) {
> -			page = alloc_page(GFP_ATOMIC);
> +			page = dev_alloc_page();
>  			if (!page) {
>  				return NULL;
>  			} else {


Best regards,
Krzysztof