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Subject[PATCH 7/9] net: use kvmalloc with __GFP_REPEAT rather than open coded variant
Date
From: Michal Hocko <mhocko@suse.com>

fq_alloc_node, alloc_netdev_mqs and netif_alloc* open code kmalloc
with vmalloc fallback. Use the kvmalloc variant instead. Keep the
__GFP_REPEAT flag based on explanation from Eric:
"
At the time, tests on the hardware I had in my labs showed that
vmalloc() could deliver pages spread all over the memory and that was a
small penalty (once memory is fragmented enough, not at boot time)
"

The way how the code is constructed means, however, that we prefer to go
and hit the OOM killer before we fall back to the vmalloc for requests
<=32kB (with 4kB pages) in the current code. This is rather disruptive for
something that can be achived with the fallback. On the other hand
__GFP_REPEAT doesn't have any useful semantic for these requests. So the
effect of this patch is that requests smaller than 64kB will fallback to
vmalloc easier now.

Cc: Eric Dumazet <edumazet@google.com>
Cc: netdev@vger.kernel.org
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
net/core/dev.c | 24 +++++++++---------------
net/sched/sch_fq.c | 12 +-----------
2 files changed, 10 insertions(+), 26 deletions(-)

diff --git a/net/core/dev.c b/net/core/dev.c
index 8637b2b71f3d..d947308ee255 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7121,12 +7121,10 @@ static int netif_alloc_rx_queues(struct net_device *dev)

BUG_ON(count < 1);

- rx = kzalloc(sz, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
- if (!rx) {
- rx = vzalloc(sz);
- if (!rx)
- return -ENOMEM;
- }
+ rx = kvzalloc(sz, GFP_KERNEL | __GFP_REPEAT);
+ if (!rx)
+ return -ENOMEM;
+
dev->_rx = rx;

for (i = 0; i < count; i++)
@@ -7163,12 +7161,10 @@ static int netif_alloc_netdev_queues(struct net_device *dev)
if (count < 1 || count > 0xffff)
return -EINVAL;

- tx = kzalloc(sz, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
- if (!tx) {
- tx = vzalloc(sz);
- if (!tx)
- return -ENOMEM;
- }
+ tx = kvzalloc(sz, GFP_KERNEL | __GFP_REPEAT);
+ if (!tx)
+ return -ENOMEM;
+
dev->_tx = tx;

netdev_for_each_tx_queue(dev, netdev_init_one_queue, NULL);
@@ -7702,9 +7698,7 @@ struct net_device *alloc_netdev_mqs(int sizeof_priv, const char *name,
/* ensure 32-byte alignment of whole construct */
alloc_size += NETDEV_ALIGN - 1;

- p = kzalloc(alloc_size, GFP_KERNEL | __GFP_NOWARN | __GFP_REPEAT);
- if (!p)
- p = vzalloc(alloc_size);
+ p = kvzalloc(alloc_size, GFP_KERNEL | __GFP_REPEAT);
if (!p)
return NULL;

diff --git a/net/sched/sch_fq.c b/net/sched/sch_fq.c
index a4f738ac7728..594f77d89f6c 100644
--- a/net/sched/sch_fq.c
+++ b/net/sched/sch_fq.c
@@ -624,16 +624,6 @@ static void fq_rehash(struct fq_sched_data *q,
q->stat_gc_flows += fcnt;
}

-static void *fq_alloc_node(size_t sz, int node)
-{
- void *ptr;
-
- ptr = kmalloc_node(sz, GFP_KERNEL | __GFP_REPEAT | __GFP_NOWARN, node);
- if (!ptr)
- ptr = vmalloc_node(sz, node);
- return ptr;
-}
-
static void fq_free(void *addr)
{
kvfree(addr);
@@ -650,7 +640,7 @@ static int fq_resize(struct Qdisc *sch, u32 log)
return 0;

/* If XPS was setup, we can allocate memory on right NUMA node */
- array = fq_alloc_node(sizeof(struct rb_root) << log,
+ array = kvmalloc_node(sizeof(struct rb_root) << log, GFP_KERNEL | __GFP_REPEAT,
netdev_queue_numa_node_read(sch->dev_queue));
if (!array)
return -ENOMEM;
--
2.11.0
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