From: "Alexei Starovoitov" <alexei.starovoitov@gmail.com>
To: "Mahnur A" <s.mahnur.a@gmail.com>, <bpf@vger.kernel.org>
Cc: <ast@kernel.org>, <daniel@iogearbox.net>, <andrii@kernel.org>,
<rostedt@goodmis.org>, <linux-kernel@vger.kernel.org>
Subject: Re: [BUG] bpf: Tracing progs on the stack save subtree can result in OOM
Date: Tue, 09 Jun 2026 15:01:51 -0700 [thread overview]
Message-ID: <DJ4UVMEEOUIF.8C5PH54S5HSK@gmail.com> (raw)
In-Reply-To: <CAJ-umGQ9edRUCnaLYTW1F2wbRDhxM7RRra545ZYbM+8++ModaA@mail.gmail.com>
On Tue Jun 9, 2026 at 10:04 AM PDT, Mahnur A wrote:
> Hi,
>
> I hit the following case on the current mainline kernel (7.1-rc7)
>
> BPF tracing programs that allocate something and have a deferred-free for it:
> Attached to any function in the stack save / unwind result in OOM.
>
>
> KASAN, slub_debug etc. all save a stack on every alloc/free.
> An example bpf program updates a map element,
> before lookup and retrieval of the timer object.
> It then calls bpf_timer_init().
> If this happens at every alloc/free event,
> a new timer object gets allocated with every map element update,
> while the previous one is deferred-free (via kfree_rcu).
It's a known design constraint.
A bunch of things in the kernel need call_rcu().
bpf is not immune to such requirements.
prev parent reply other threads:[~2026-06-09 22:01 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-09 17:04 [BUG] bpf: Tracing progs on the stack save subtree can result in OOM Mahnur A
2026-06-09 22:01 ` Alexei Starovoitov [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=DJ4UVMEEOUIF.8C5PH54S5HSK@gmail.com \
--to=alexei.starovoitov@gmail.com \
--cc=andrii@kernel.org \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=linux-kernel@vger.kernel.org \
--cc=rostedt@goodmis.org \
--cc=s.mahnur.a@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.