linux-kernel - Re: [PATCH net] bpf: cpumap: use GFP_KERNEL instead of GFP_ATOMIC in __cpu_map_entry

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Date:   Wed, 14 Feb 2018 15:37:28 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Jason Wang <jasowang@...hat.com>, ast@...nel.org,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     mst@...hat.com, Michal Hocko <mhocko@...nel.org>,
        Matthew Wilcox <willy@...radead.org>,
        Jesper Dangaard Brouer <brouer@...hat.com>,
        akpm@...ux-foundation.org, dhowells@...hat.com, hannes@...xchg.org
Subject: Re: [PATCH net] bpf: cpumap: use GFP_KERNEL instead of GFP_ATOMIC in
 __cpu_map_entry_alloc()

On 02/14/2018 03:17 PM, 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@...kaller.appspotmail.com
> Fixes: 0bf7800f1799 ("ptr_ring: try vmalloc() when kmalloc() fails")
> Cc: Michal Hocko <mhocko@...nel.org>
> Cc: Daniel Borkmann <daniel@...earbox.net>
> Cc: Matthew Wilcox <willy@...radead.org>
> Cc: Jesper Dangaard Brouer <brouer@...hat.com>
> Cc: akpm@...ux-foundation.org
> Cc: dhowells@...hat.com
> Cc: hannes@...xchg.org
> Signed-off-by: Jason Wang <jasowang@...hat.com>

Applied to bpf tree, thanks Jason!