From: Song Liu <songliubraving@fb.com>
To: <linux-kernel@vger.kernel.org>, <bpf@vger.kernel.org>,
<netdev@vger.kernel.org>
Cc: <kernel-team@fb.com>, Song Liu <songliubraving@fb.com>
Subject: [PATCH bpf-next 0/2] bpf/stackmap: fix A-A deadlock in bpf_get_stack()
Date: Wed, 9 Oct 2019 23:19:14 -0700 [thread overview]
Message-ID: <20191010061916.198761-1-songliubraving@fb.com> (raw)
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
For more details on how to reproduce this is error, please refer to 2/2.
Fix this issue by checking a new helper this_rq_is_locked(). If the
rq_lock is already locked, postpone up_read() in irq_work, just like the
in_nmi() case.
Song Liu (2):
sched: introduce this_rq_is_locked()
bpf/stackmap: fix A-A deadlock in bpf_get_stack()
include/linux/sched.h | 1 +
kernel/bpf/stackmap.c | 2 +-
kernel/sched/core.c | 8 ++++++++
3 files changed, 10 insertions(+), 1 deletion(-)
--
2.17.1
next reply other threads:[~2019-10-10 6:19 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-10 6:19 Song Liu [this message]
2019-10-10 6:19 ` [PATCH bpf-next 1/2] sched: introduce this_rq_is_locked() Song Liu
2019-10-10 6:19 ` [PATCH bpf-next 2/2] bpf/stackmap: fix A-A deadlock in bpf_get_stack() Song Liu
2019-10-10 7:36 ` Peter Zijlstra
2019-10-10 17:19 ` Alexei Starovoitov
2019-10-10 17:46 ` Peter Zijlstra
2019-10-10 18:06 ` Alexei Starovoitov
2019-10-14 9:09 ` Peter Zijlstra
2019-10-14 20:12 ` Song Liu
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