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Date: Thu, 2 Apr 2026 16:38:34 +0800
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Subject: Re: [PATCH net v1] net: skb: fix cross-cache free of KFENCE-allocated
 skb head
To: Eric Dumazet <edumazet@google.com>
Cc: netdev@vger.kernel.org, Antonius <antonius@bluedragonsec.com>,
 "David S. Miller" <davem@davemloft.net>, Jakub Kicinski <kuba@kernel.org>,
 Paolo Abeni <pabeni@redhat.com>, Simon Horman <horms@kernel.org>,
 Jason Xing <kerneljasonxing@gmail.com>, Kuniyuki Iwashima
 <kuniyu@google.com>, Michal Luczaj <mhal@rbox.co>,
 Mina Almasry <almasrymina@google.com>, Eric Biggers <ebiggers@google.com>,
 =?UTF-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= <toke@redhat.com>,
 Soheil Hassas Yeganeh <soheil@google.com>,
 Alexander Duyck <alexanderduyck@fb.com>, linux-kernel@vger.kernel.org,
 bpf@vger.kernel.org
References: <20260402033138.388574-1-jiayuan.chen@linux.dev>
 <CANn89iLdRZd-qO4tRpSGamHpggh=r5vM4xes5npYCnkwcNG89A@mail.gmail.com>
 <ad90b2a9-0f67-4796-94bc-9dbb76a575af@linux.dev>
 <CANn89iLLwk9G6K8r=hOxsQQ2AsW751E+2pOoud9c-R+R-3i6hg@mail.gmail.com>
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From: Jiayuan Chen <jiayuan.chen@linux.dev>
In-Reply-To: <CANn89iLLwk9G6K8r=hOxsQQ2AsW751E+2pOoud9c-R+R-3i6hg@mail.gmail.com>
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On 4/2/26 4:03 PM, Eric Dumazet wrote:
> On Wed, Apr 1, 2026 at 9:15 PM Jiayuan Chen <jiayuan.chen@linux.dev> wrote:
>> If we no longer care about the cost of accessing a struct page in the
>> free path, which the original commit was trying to avoid, this is
>> indeed the simplest fix — kfree() correctly handles objects via
>> virt_to_slab.
> We only have SLUB in modern kernels, kmem_cache_free() needs to touch it.
>
> Using is_kfence_address() in net/core/skbuff.c is pushing too hard in
> my opinion.
Thanks, I understand.