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Rao" , Andrey Ryabinin , Alexander Potapenko , Andrey Konovalov , Dmitry Vyukov , Vincenzo Frascino , kasan-dev@googlegroups.com, "David S. Miller" , Steven Rostedt , Mathieu Desnoyers , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim , Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , "Liang, Kan" , Thomas Gleixner , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Cc: linux-kernel@vger.kernel.org, Jinchao Wang Subject: [PATCH v3 08/19] mm/ksw: support CPU hotplug Date: Wed, 10 Sep 2025 13:23:17 +0800 Message-ID: <20250910052335.1151048-9-wangjinchao600@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250910052335.1151048-1-wangjinchao600@gmail.com> References: <20250910052335.1151048-1-wangjinchao600@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Register CPU online/offline callbacks via cpuhp_setup_state_nocalls() so stack watches are installed/removed dynamically as CPUs come online or go offline. Signed-off-by: Jinchao Wang --- mm/kstackwatch/watch.c | 36 ++++++++++++++++++++++++++++++++++++ 1 file changed, 36 insertions(+) diff --git a/mm/kstackwatch/watch.c b/mm/kstackwatch/watch.c index e02ffc3231ad..d95efefdffe9 100644 --- a/mm/kstackwatch/watch.c +++ b/mm/kstackwatch/watch.c @@ -1,6 +1,7 @@ // SPDX-License-Identifier: GPL-2.0 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt =20 +#include #include #include #include @@ -67,6 +68,32 @@ static void ksw_watch_on_local_cpu(void *data) } } =20 +static int ksw_cpu_online(unsigned int cpu) +{ + struct perf_event *bp; + + bp =3D perf_event_create_kernel_counter(&watch_attr, cpu, NULL, + ksw_watch_handler, NULL); + if (IS_ERR(bp)) { + pr_err("Failed to create watch on CPU %d: %ld\n", cpu, + PTR_ERR(bp)); + return PTR_ERR(bp); + } + + per_cpu(*watch_events, cpu) =3D bp; + per_cpu(watch_csd, cpu) =3D CSD_INIT(ksw_watch_on_local_cpu, NULL); + return 0; +} + +static int ksw_cpu_offline(unsigned int cpu) +{ + struct perf_event *bp =3D per_cpu(*watch_events, cpu); + + if (bp) + unregister_hw_breakpoint(bp); + return 0; +} + int ksw_watch_on(u64 watch_addr, u64 watch_len) { unsigned long flags; @@ -141,6 +168,15 @@ int ksw_watch_init(void) return ret; } =20 + ret =3D cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, + "kstackwatch:online", ksw_cpu_online, + ksw_cpu_offline); + if (ret < 0) { + unregister_wide_hw_breakpoint(watch_events); + pr_err("Failed to register CPU hotplug notifier\n"); + return ret; + } + return 0; } =20 --=20 2.43.0