page_frag: unify gfp bits for order 3 page allocation

Currently there seems to be three page frag implementations
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 masked off to avoid
direct reclaim in vhost_net_page_frag_refill(), but it is
not masked off in __page_frag_cache_refill().

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

Leave the gfp unifying for page frag implementation in sock.c
for now as suggested by Paolo Abeni.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
CC: Alexander Duyck <alexander.duyck@gmail.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index f2ed7167c848096ef8c8f338325bedc278df65fe..e574e21cc0ca39d1e477ea3e28ababbcdfd9a49c 100644 (file)
--- 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 c0f7e67c42500e2ba2d624ff934b52bfb22d1aea..636145c29f703a19507403d59460b3c06b363fc9 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -4685,8 +4685,8 @@ 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;