From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161527AbeBNRp5 (ORCPT ); Wed, 14 Feb 2018 12:45:57 -0500 Received: from www62.your-server.de ([213.133.104.62]:51223 "EHLO www62.your-server.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161455AbeBNRpj (ORCPT ); Wed, 14 Feb 2018 12:45:39 -0500 Subject: Re: [PATCH net] bpf: cpumap: use GFP_KERNEL instead of GFP_ATOMIC in __cpu_map_entry_alloc() To: "Michael S. Tsirkin" , Jason Wang Cc: ast@kernel.org, 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 References: <1518617854-4486-1-git-send-email-jasowang@redhat.com> <20180214190311-mutt-send-email-mst@kernel.org> From: Daniel Borkmann Message-ID: Date: Wed, 14 Feb 2018 18:45:32 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.3.0 MIME-Version: 1.0 In-Reply-To: <20180214190311-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Authenticated-Sender: daniel@iogearbox.net Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/14/2018 06:04 PM, Michael S. Tsirkin wrote: > 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? It's up to you if you think a revert is needed. The below is fine and small enough in any case for cpumap, imho. >> 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