From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH net] bpf: cpumap: use GFP_KERNEL instead of GFP_ATOMIC in __cpu_map_entry_alloc() Date: Wed, 14 Feb 2018 19:04:56 +0200 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 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 To: Jason Wang Return-path: Content-Disposition: inline In-Reply-To: <1518617854-4486-1-git-send-email-jasowang@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.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