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SubjectRe: __GFP_REPEAT usage in fq_alloc_node
On Fri 06-01-17 17:07:43, Michal Hocko wrote:
> On Fri 06-01-17 07:39:14, Eric Dumazet wrote:
> > On Fri, Jan 6, 2017 at 7:20 AM, Michal Hocko <mhocko@kernel.org> wrote:
> > >
> > > Hi Eric,
> > > I am currently checking kmalloc with vmalloc fallback users and convert
> > > them to a new kvmalloc helper [1]. While I am adding a support for
> > > __GFP_REPEAT to kvmalloc [2] I was wondering what is the reason to use
> > > __GFP_REPEAT in fq_alloc_node in the first place. c3bd85495aef
> > > ("pkt_sched: fq: more robust memory allocation") doesn't mention
> > > anything. Could you clarify this please?
> > >
> > > Thanks!
> >
> > I guess this question applies to all __GFP_REPEAT usages in net/ ?
>
> I am _currently_ interested only in those which have vmalloc fallback
> and cannot see more of them. Maybe my git grep foo needs some help.

I was obviously blind...
---
From 8eadf8774daecdd6c4de37339216282a16920458 Mon Sep 17 00:00:00 2001
From: Michal Hocko <mhocko@suse.com>
Date: Fri, 6 Jan 2017 17:03:31 +0100
Subject: [PATCH] net: use kvmalloc rather than open coded variant

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)
"

Cc: Eric Dumazet <edumazet@google.com>
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 56818f7eab2b..5cf2762387aa 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -7111,12 +7111,10 @@ 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++)
@@ -7153,12 +7151,10 @@ 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);
@@ -7691,9 +7687,7 @@ 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
--
Michal Hocko
SUSE Labs

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