diff mbox series

[net-next,2/6] page_frag: unify gfp bit for order 3 page allocation

Message ID 20231205113444.63015-3-linyunsheng@huawei.com (mailing list archive)
State New
Headers show
Series [net-next,1/6] mm/page_alloc: modify page_frag_alloc_align() to accept align as an argument | expand

Commit Message

Yunsheng Lin Dec. 5, 2023, 11:34 a.m. UTC 
Currently there seems to be three page frag implementions
which all try to allocate order 3 page, if that fails, it
then fail back to allocate order 0 page, and each of them
all allow order 3 page allocation to fail under certain
condition by using specific gfp bits.

The gfp bits for order 3 page allocation are different
between different implementation, __GFP_NOMEMALLOC is
or'd to forbid access to emergency reserves memory for
__page_frag_cache_refill(), but it is not or'd in other
implementions, __GFP_DIRECT_RECLAIM is xor'd to avoid
direct reclaim in skb_page_frag_refill(), but it is not
xor'd in __page_frag_cache_refill().

This patch unifies the gfp bits used between different
implementions by or'ing __GFP_NOMEMALLOC and xor'ing
__GFP_DIRECT_RECLAIM for order 3 page allocation to avoid
possible pressure for mm.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
CC: Alexander Duyck <alexander.duyck@gmail.com>
---
 drivers/vhost/net.c | 2 +-
 mm/page_alloc.c     | 4 ++--
 net/core/sock.c     | 2 +-
 3 files changed, 4 insertions(+), 4 deletions(-)

Comments

Jakub Kicinski Dec. 7, 2023, 3:15 a.m. UTC | #1 
On Tue, 5 Dec 2023 19:34:40 +0800 Yunsheng Lin wrote:
> __GFP_DIRECT_RECLAIM is xor'd to avoid
> direct reclaim in skb_page_frag_refill(), but it is not
> xor'd in __page_frag_cache_refill().

xor is not the same thing as masking a bit off.
The patch itself LGTM.
Yunsheng Lin Dec. 7, 2023, 11:27 a.m. UTC | #2 
On 2023/12/7 11:15, Jakub Kicinski wrote:
> On Tue, 5 Dec 2023 19:34:40 +0800 Yunsheng Lin wrote:
>> __GFP_DIRECT_RECLAIM is xor'd to avoid
>> direct reclaim in skb_page_frag_refill(), but it is not
>> xor'd in __page_frag_cache_refill().
> 
> xor is not the same thing as masking a bit off.

You are right.
Will use 'mask off', thanks.

> The patch itself LGTM.
> .
>
diff mbox series

Patch

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index f2ed7167c848..e574e21cc0ca 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -670,7 +670,7 @@  static bool vhost_net_page_frag_refill(struct vhost_net *net, unsigned int sz,
 		/* Avoid direct reclaim but allow kswapd to wake */
 		pfrag->page = alloc_pages((gfp & ~__GFP_DIRECT_RECLAIM) |
 					  __GFP_COMP | __GFP_NOWARN |
-					  __GFP_NORETRY,
+					  __GFP_NORETRY | __GFP_NOMEMALLOC,
 					  SKB_FRAG_PAGE_ORDER);
 		if (likely(pfrag->page)) {
 			pfrag->size = PAGE_SIZE << SKB_FRAG_PAGE_ORDER;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 9a16305cf985..1f0b36dd81b5 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4693,8 +4693,8 @@  static struct page *__page_frag_cache_refill(struct page_frag_cache *nc,
 	gfp_t gfp = gfp_mask;
 
 #if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
-	gfp_mask |= __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY |
-		    __GFP_NOMEMALLOC;
+	gfp_mask = (gfp_mask & ~__GFP_DIRECT_RECLAIM) |  __GFP_COMP |
+		   __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC;
 	page = alloc_pages_node(NUMA_NO_NODE, gfp_mask,
 				PAGE_FRAG_CACHE_MAX_ORDER);
 	nc->size = page ? PAGE_FRAG_CACHE_MAX_SIZE : PAGE_SIZE;
diff --git a/net/core/sock.c b/net/core/sock.c
index fef349dd72fa..4efa9cae4b0d 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2904,7 +2904,7 @@  bool skb_page_frag_refill(unsigned int sz, struct page_frag *pfrag, gfp_t gfp)
 		/* Avoid direct reclaim but allow kswapd to wake */
 		pfrag->page = alloc_pages((gfp & ~__GFP_DIRECT_RECLAIM) |
 					  __GFP_COMP | __GFP_NOWARN |
-					  __GFP_NORETRY,
+					  __GFP_NORETRY | __GFP_NOMEMALLOC,
 					  SKB_FRAG_PAGE_ORDER);
 		if (likely(pfrag->page)) {
 			pfrag->size = PAGE_SIZE << SKB_FRAG_PAGE_ORDER;