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Thu, 15 Oct 2026 19:02:34 -0700 (PDT) Content-Type: text/plain; charset=UTF-8 Date: Fri, 16 Oct 2026 02:02:34 +0000 Message-Id: Cc: , , , Subject: Re: [PATCH bpf-next v4 1/8] bpf: Use mapping tree to zap arena VMAs From: "Alexei Starovoitov" To: "Emil Tsalapatis" , In-Reply-To: <20261014233442.8392-2-emil@etsalapatis.com> References: <20261014233442.8392-1-emil@etsalapatis.com> <20261014233442.8392-2-emil@etsalapatis.com> X-Mailer: mkdraft (claude review draft; edit before sending) Content-Transfer-Encoding: 8bit Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, Oct 14, 2026 at 11:34 PM Emil Tsalapatis wrote: > This refactoring is necessary to avoid deadlocks between arena_vm_fault > and page zapping in subsequent patches. [...] > @@ -89,6 +89,7 @@ struct bpf_map_ops { > /* funcs callable from userspace (via syscall) */ > int (*map_alloc_check)(union bpf_attr *attr); > struct bpf_map *(*map_alloc)(union bpf_attr *attr); > + struct file *(*map_get_file)(struct bpf_map *map, int flags); This is quite heavy. The deadlock is there only because arena_vm_fault() in patch 7 sleeps on opref with mmap_lock held. See my reply there.