From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1033328AbeBNRFA (ORCPT ); Wed, 14 Feb 2018 12:05:00 -0500 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:58780 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1032907AbeBNRE6 (ORCPT ); Wed, 14 Feb 2018 12:04:58 -0500 Date: Wed, 14 Feb 2018 19:04:56 +0200 From: "Michael S. Tsirkin" To: Jason Wang Cc: ast@kernel.org, daniel@iogearbox.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Michal Hocko , Matthew Wilcox , Jesper Dangaard Brouer , akpm@linux-foundation.org, dhowells@redhat.com, hannes@cmpxchg.org Subject: Re: [PATCH net] bpf: cpumap: use GFP_KERNEL instead of GFP_ATOMIC in __cpu_map_entry_alloc() Message-ID: <20180214190311-mutt-send-email-mst@kernel.org> References: <1518617854-4486-1-git-send-email-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1518617854-4486-1-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 14, 2018 at 10:17:34PM +0800, Jason Wang wrote: > There're several implications after commit 0bf7800f1799 ("ptr_ring: > try vmalloc() when kmalloc() fails") with the using of vmalloc() since > can't allow GFP_ATOMIC but mandate GFP_KERNEL. This will lead a WARN > since cpumap try to call with GFP_ATOMIC. Fortunately, entry > allocation of cpumap can only be done through syscall path which means > GFP_ATOMIC is not necessary, so fixing this by replacing GFP_ATOMIC > with GFP_KERNEL. > > Reported-by: syzbot+1a240cdb1f4cc88819df@syzkaller.appspotmail.com > Fixes: 0bf7800f1799 ("ptr_ring: try vmalloc() when kmalloc() fails") > Cc: Michal Hocko > Cc: Daniel Borkmann > Cc: Matthew Wilcox > Cc: Jesper Dangaard Brouer > Cc: akpm@linux-foundation.org > Cc: dhowells@redhat.com > Cc: hannes@cmpxchg.org > Signed-off-by: Jason Wang Frankly I'd start with the revert. The original patch was rushed into net without enough justification IMHO, and we just seem to keep piling up these things. How about deferring all these ideas to net-next? > --- > kernel/bpf/cpumap.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c > index fbfdada6..a4bb0b3 100644 > --- a/kernel/bpf/cpumap.c > +++ b/kernel/bpf/cpumap.c > @@ -334,7 +334,7 @@ static int cpu_map_kthread_run(void *data) > static struct bpf_cpu_map_entry *__cpu_map_entry_alloc(u32 qsize, u32 cpu, > int map_id) > { > - gfp_t gfp = GFP_ATOMIC|__GFP_NOWARN; > + gfp_t gfp = GFP_KERNEL | __GFP_NOWARN; > struct bpf_cpu_map_entry *rcpu; > int numa, err; > > -- > 2.7.4