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Wed, 28 Jan 2026 00:19:23 -0800 (PST) Message-ID: <874829ba-00b9-49cd-8f67-a4c33a8f409f@gmail.com> Date: Wed, 28 Jan 2026 16:19:14 +0800 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] perf callchain: Fix suspicious RCU usage in get_callchain_entry() To: Qing Wang , andrii.nakryiko@gmail.com Cc: acme@kernel.org, adrian.hunter@intel.com, alexander.shishkin@linux.intel.com, bpf@vger.kernel.org, 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, radoslaw.zielonek@gmail.com, syzbot+72a43cdb78469f7fbad1@syzkaller.appspotmail.com References: <20260128062656.1860201-1-wangqing7171@gmail.com> From: Tao Chen In-Reply-To: <20260128062656.1860201-1-wangqing7171@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit 在 2026/1/28 14:26, Qing Wang 写道: > On Fri, 19 Jul 2024 at 01:41, Andrii Nakryiko wrote: >> Which is what I'm doing in [0]. Radoslaw, can you please help >> validating if those changes are enough to fix this issue or we need to >> do some more? >> >> [0] https://patchwork.kernel.org/project/netdevbpf/patch/20240709204245.3= >> 847811-10-andrii@kernel.org/ >> >>> >>>> --- >>>> kernel/events/callchain.c | 11 +++++++++-- >>>> 1 file changed, 9 insertions(+), 2 deletions(-) >>>> > > Hi, > > I found this issue still exists after your patch in upstream and I have a > patch to fix it. > > Patch here: https://lore.kernel.org/all/20260128061753.1857803-1-wangqing7171@gmail.com/T/ > > Looking forward to your review. > > -- > Best regards, > Qing > Hi Qing, I have a change that will remove RCU. As Andrii pointed out, using get_callchain_entry without RCU lock in BPF appears to be safe for now. Please point out if I've missed anything. https://lore.kernel.org/bpf/fb745675-e25c-4dcc-be4b-4a4411056755@linux.dev/T/#mc0fc5e0fec2e6456f72f402308fd4e397ba19d09 -- Best Regards Tao Chen