From: Eduard Zingerman <eddyz87@gmail.com>
To: Kumar Kartikeya Dwivedi <memxor@gmail.com>, bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>,
Andrii Nakryiko <andrii@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Emil Tsalapatis <emil@etsalapatis.com>,
Nicholas Carlini <npc@anthropic.com>,
kkd@meta.com, kernel-team@meta.com
Subject: Re: [PATCH bpf v1 5/8] bpf: Mark faultable stack helpers as sleepable
Date: Thu, 03 Sep 2026 15:00:37 -0700 [thread overview]
Message-ID: <0315aef6b1dcd90696787b4e8859a6a65bfd3085.camel@gmail.com> (raw)
In-Reply-To: <20260903214758.2727663-6-memxor@gmail.com>
On Thu, 2026-09-03 at 23:47 +0200, Kumar Kartikeya Dwivedi wrote:
> The faultable variants of bpf_get_stack() and bpf_get_task_stack() pass
> may_fault=true into the common stack collection code. Resolving user-space
> build IDs may then call build_id_parse_file() and block on filesystem
> reads.
It's kinda in the helpers name.
> Neither helper prototype sets might_sleep. Since prototype selection uses
> the sleepability of the whole program, the verifier can still allow these
> helpers from a non-sleepable region within that program, such as an
> explicit RCU or preemption-disabled region. The task-stack helper can also
> be called from a non-sleepable timer callback of a sleepable program.
>
> Mark both faultable prototypes as sleepable. The existing helper context
> check then rejects these calls while continuing to allow them in genuinely
> sleepable contexts.
>
> Fixes: d4dd9775ec24 ("bpf: wire up sleepable bpf_get_stack() and bpf_get_task_stack() helpers")
> Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
> ---
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
next prev parent reply other threads:[~2026-09-03 22:00 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-03 21:47 [PATCH bpf v1 0/8] Misc bug fixes - part 2 Kumar Kartikeya Dwivedi
2026-09-03 21:47 ` [PATCH bpf v1 1/8] bpf: Check ancestor frames for rbtree callbacks Kumar Kartikeya Dwivedi
2026-09-03 22:40 ` Eduard Zingerman
2026-09-03 22:56 ` bot+bpf-ci
2026-09-03 21:47 ` [PATCH bpf v1 2/8] selftests/bpf: Check rbtree callback restrictions in subprogs Kumar Kartikeya Dwivedi
2026-09-03 22:56 ` bot+bpf-ci
2026-09-03 21:47 ` [PATCH bpf v1 3/8] bpf: Mark bpf_btf_find_by_name_kind() as sleepable Kumar Kartikeya Dwivedi
2026-09-03 22:15 ` Eduard Zingerman
2026-09-03 21:47 ` [PATCH bpf v1 4/8] selftests/bpf: Test btf lookup helper sleepability Kumar Kartikeya Dwivedi
2026-09-03 21:47 ` [PATCH bpf v1 5/8] bpf: Mark faultable stack helpers as sleepable Kumar Kartikeya Dwivedi
2026-09-03 22:00 ` Eduard Zingerman [this message]
2026-09-03 22:56 ` bot+bpf-ci
2026-09-03 21:47 ` [PATCH bpf v1 6/8] selftests/bpf: Check faultable stack helper contexts Kumar Kartikeya Dwivedi
2026-09-03 22:56 ` bot+bpf-ci
2026-09-03 21:47 ` [PATCH bpf v1 7/8] bpf: Reject legacy packet loads from callbacks Kumar Kartikeya Dwivedi
2026-09-03 21:58 ` Eduard Zingerman
2026-09-04 2:22 ` Alexei Starovoitov
2026-09-03 21:47 ` [PATCH bpf v1 8/8] selftests/bpf: " Kumar Kartikeya Dwivedi
2026-09-04 2:30 ` [PATCH bpf v1 0/8] Misc bug fixes - part 2 patchwork-bot+netdevbpf
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