From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: Song Liu <songliubraving@fb.com>
Cc: LKML <linux-kernel@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
Network Development <netdev@vger.kernel.org>,
sashal@kernel.org, Kernel Team <kernel-team@fb.com>,
stable <stable@vger.kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>
Subject: Re: [PATCH v2 bpf-next] bpf/stackmap: fix deadlock with rq_lock in bpf_get_stack()
Date: Wed, 16 Oct 2019 10:43:36 -0700 [thread overview]
Message-ID: <CAADnVQKn3RZnAZAOSg1yoQmo9doeGouEBkcFzmZGWLU7QqjJOA@mail.gmail.com> (raw)
In-Reply-To: <20191014171223.357174-1-songliubraving@fb.com>
On Mon, Oct 14, 2019 at 10:12 AM Song Liu <songliubraving@fb.com> wrote:
>
> bpf stackmap with build-id lookup (BPF_F_STACK_BUILD_ID) can trigger A-A
> deadlock on rq_lock():
>
> rcu: INFO: rcu_sched detected stalls on CPUs/tasks:
> [...]
> Call Trace:
> try_to_wake_up+0x1ad/0x590
> wake_up_q+0x54/0x80
> rwsem_wake+0x8a/0xb0
> bpf_get_stack+0x13c/0x150
> bpf_prog_fbdaf42eded9fe46_on_event+0x5e3/0x1000
> bpf_overflow_handler+0x60/0x100
> __perf_event_overflow+0x4f/0xf0
> perf_swevent_overflow+0x99/0xc0
> ___perf_sw_event+0xe7/0x120
> __schedule+0x47d/0x620
> schedule+0x29/0x90
> futex_wait_queue_me+0xb9/0x110
> futex_wait+0x139/0x230
> do_futex+0x2ac/0xa50
> __x64_sys_futex+0x13c/0x180
> do_syscall_64+0x42/0x100
> entry_SYSCALL_64_after_hwframe+0x44/0xa9
>
> This can be reproduced by:
> 1. Start a multi-thread program that does parallel mmap() and malloc();
> 2. taskset the program to 2 CPUs;
> 3. Attach bpf program to trace_sched_switch and gather stackmap with
> build-id, e.g. with trace.py from bcc tools:
> trace.py -U -p <pid> -s <some-bin,some-lib> t:sched:sched_switch
>
> A sample reproducer is attached at the end.
>
> This could also trigger deadlock with other locks that are nested with
> rq_lock.
>
> Fix this by checking whether irqs are disabled. Since rq_lock and all
> other nested locks are irq safe, it is safe to do up_read() when irqs are
> not disable. If the irqs are disabled, postpone up_read() in irq_work.
>
> Fixes: commit 615755a77b24 ("bpf: extend stackmap to save binary_build_id+offset instead of address")
> Cc: stable@vger.kernel.org # v4.17+
> Cc: Peter Zijlstra <peterz@infradead.org>
> Cc: Alexei Starovoitov <ast@kernel.org>
> Cc: Daniel Borkmann <daniel@iogearbox.net>
> Signed-off-by: Song Liu <songliubraving@fb.com>
I fixed 'Fixes' tag and applied to bpf-next.
Thanks
prev parent reply other threads:[~2019-10-16 17:43 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-14 17:12 [PATCH v2 bpf-next] bpf/stackmap: fix deadlock with rq_lock in bpf_get_stack() Song Liu
2019-10-16 17:43 ` 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=CAADnVQKn3RZnAZAOSg1yoQmo9doeGouEBkcFzmZGWLU7QqjJOA@mail.gmail.com \
--to=alexei.starovoitov@gmail.com \
--cc=ast@kernel.org \
--cc=bpf@vger.kernel.org \
--cc=daniel@iogearbox.net \
--cc=kernel-team@fb.com \
--cc=linux-kernel@vger.kernel.org \
--cc=netdev@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=sashal@kernel.org \
--cc=songliubraving@fb.com \
--cc=stable@vger.kernel.org \
/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 a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).