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Tue, 27 Jan 2026 19:55:15 -0800 (PST) From: Qing Wang To: syzbot+72a43cdb78469f7fbad1@syzkaller.appspotmail.com Cc: acme@kernel.org, adrian.hunter@intel.com, alexander.shishkin@linux.intel.com, irogers@google.com, jolsa@kernel.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, mark.rutland@arm.com, mingo@redhat.com, namhyung@kernel.org, peterz@infradead.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [perf?] WARNING: suspicious RCU usage in get_callchain_entry Date: Wed, 28 Jan 2026 11:55:08 +0800 Message-Id: <20260128035508.1840613-1-wangqing7171@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <000000000000fe324606174e1f9e@google.com> References: <000000000000fe324606174e1f9e@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit #syz test diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index da3d328f5c15..f97d4aa9d038 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -460,7 +460,7 @@ static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task, max_depth = stack_map_calculate_max_depth(size, elem_size, flags); - if (may_fault) + if (!trace_in) rcu_read_lock(); /* need RCU for perf's callchain below */ if (trace_in) { @@ -474,7 +474,7 @@ static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task, } if (unlikely(!trace) || trace->nr < skip) { - if (may_fault) + if (!trace_in) rcu_read_unlock(); goto err_fault; } @@ -494,7 +494,7 @@ static long __bpf_get_stack(struct pt_regs *regs, struct task_struct *task, } /* trace/ips should not be dereferenced after this point */ - if (may_fault) + if (!trace_in) rcu_read_unlock(); if (user_build_id)