From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: kernel 3.2.27 on arm: WARNING: at mm/page_alloc.c:2109 __alloc_pages_nodemask+0x1d4/0x68c() Date: Fri, 05 Oct 2012 15:02:53 +0200 Message-ID: <1349442173.21172.66.camel@edumazet-glaptop> References: <20120829002548.GA7063@aldebaran.gro-tsen.net> <1349366521.2532.12.camel@sakura.staff.proxad.net> <1349368171.16011.79.camel@edumazet-glaptop> <1349422868.21172.38.camel@edumazet-glaptop> <1349434194.16710.44.camel@sakura.staff.proxad.net> <1349439732.21172.52.camel@edumazet-glaptop> <1349441509.28867.17.camel@sakura.staff.proxad.net> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: David Madore , Francois Romieu , netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Hugh Dickins To: mbizon@freebox.fr Return-path: In-Reply-To: <1349441509.28867.17.camel@sakura.staff.proxad.net> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On Fri, 2012-10-05 at 14:51 +0200, Maxime Bizon wrote: > > New convention would be : pass number of needed bytes after current > > tail, not after current end. > > Fully agree on this > Here is the proposal : Change all occurrences of : pskb_expand_head(skb, 0, 0, gfp) to pskb_realloc_head(skb, gfp) [ an inline calling a common function ] And few other pskb_expand_head() calls a new function pskb_may_expand_head(skb, nhead, ntail, gfp) [ an inline calling same common function ] nhead : number of needed bytes before [data,tail] portion (might be already < skb_headroom(skb)) ntail : number of needed bytes after [data,tail] portion (might be already > skb_tailroom(skb)) For example, net/xfrm/xfrm_output.c would be like the following : (Note how all the various ugly tests will be centralized in the common function) And the common function would now know the caller intent. diff --git a/net/xfrm/xfrm_output.c b/net/xfrm/xfrm_output.c index 95a338c..15760df 100644 --- a/net/xfrm/xfrm_output.c +++ b/net/xfrm/xfrm_output.c @@ -24,18 +24,10 @@ static int xfrm_output2(struct sk_buff *skb); static int xfrm_skb_check_space(struct sk_buff *skb) { struct dst_entry *dst = skb_dst(skb); - int nhead = dst->header_len + LL_RESERVED_SPACE(dst->dev) - - skb_headroom(skb); - int ntail = dst->dev->needed_tailroom - skb_tailroom(skb); - - if (nhead <= 0) { - if (ntail <= 0) - return 0; - nhead = 0; - } else if (ntail < 0) - ntail = 0; - - return pskb_expand_head(skb, nhead, ntail, GFP_ATOMIC); + int nhead = dst->header_len + LL_RESERVED_SPACE(dst->dev); + int ntail = dst->dev->needed_tailroom; + + return pskb_may_expand_head(skb, nhead, ntail, GFP_ATOMIC); } static int xfrm_output_one(struct sk_buff *skb, int err)