Re: [PATCH net-next] netlink: do not enter direct reclaim from netlink_trim()

[David Miller]

From: Eric Dumazet 
Date: Fri, 13 Jan 2017 09:11:22 -0800

> From: Eric Dumazet 
> 
> In commit d35c99ff77ecb ("netlink: do not enter direct reclaim from
> netlink_dump()") we made sure to not trigger expensive memory reclaim.
> 
> Problem is that a bit later, netlink_trim() might be called and
> trigger memory reclaim.
> 
> netlink_trim() should be best effort, and really as fast as possible.
> Under memory pressure, it is fine to not trim this skb.
> 
> Signed-off-by: Eric Dumazet 

Applied, thanks Eric.

Re: [PATCH net-next] netlink: do not enter direct reclaim from netlink_trim()

[Alexei Starovoitov]

On Fri, Jan 13, 2017 at 09:11:22AM -0800, Eric Dumazet wrote:
> From: Eric Dumazet 
> 
> In commit d35c99ff77ecb ("netlink: do not enter direct reclaim from
> netlink_dump()") we made sure to not trigger expensive memory reclaim.
> 
> Problem is that a bit later, netlink_trim() might be called and
> trigger memory reclaim.
> 
> netlink_trim() should be best effort, and really as fast as possible.
> Under memory pressure, it is fine to not trim this skb.
> 
> Signed-off-by: Eric Dumazet 

Thanks!
Acked-by: Alexei Starovoitov 

[PATCH net-next] netlink: do not enter direct reclaim from netlink_trim()

[Eric Dumazet]

From: Eric Dumazet 

In commit d35c99ff77ecb ("netlink: do not enter direct reclaim from
netlink_dump()") we made sure to not trigger expensive memory reclaim.

Problem is that a bit later, netlink_trim() might be called and
trigger memory reclaim.

netlink_trim() should be best effort, and really as fast as possible.
Under memory pressure, it is fine to not trim this skb.

Signed-off-by: Eric Dumazet 
---
 net/netlink/af_netlink.c |4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 
161b628ab2b08bf4321dbe617022c4c50486534d..edcc1e19ad532641f51f6809b8c90d1e377081ff
 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1210,7 +1210,9 @@ static struct sk_buff *netlink_trim(struct sk_buff *skb, 
gfp_t allocation)
skb = nskb;
}
 
-   if (!pskb_expand_head(skb, 0, -delta, allocation))
+   if (!pskb_expand_head(skb, 0, -delta,
+ (allocation & ~__GFP_DIRECT_RECLAIM) |
+ __GFP_NOWARN | __GFP_NORETRY))
skb->truesize -= delta;
 
return skb;