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Mon, 29 Sep 2025 19:45:09 -0700 (PDT) From: Jinchao Wang To: Andrew Morton , Masami Hiramatsu , Peter Zijlstra , Mike Rapoport , Alexander Potapenko , Randy Dunlap , Marco Elver , Jonathan Corbet , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. 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Miller" , Mathieu Desnoyers , linux-trace-kernel@vger.kernel.org Cc: Jinchao Wang Subject: [PATCH v6 10/23] mm/ksw: support CPU hotplug Date: Tue, 30 Sep 2025 10:43:31 +0800 Message-ID: <20250930024402.1043776-11-wangjinchao600@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20250930024402.1043776-1-wangjinchao600@gmail.com> References: <20250930024402.1043776-1-wangjinchao600@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 21E8940007 X-Stat-Signature: d6myh5du7r8rj9ozduboppco9ospzeod X-Rspam-User: X-Rspamd-Server: rspam09 X-HE-Tag: 1759200310-899547 X-HE-Meta: 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 J3idE0le 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Register CPU online/offline callbacks via cpuhp_setup_state_nocalls() so stack watches are installed/removed dynamically as CPUs come online or go offline. When a new CPU comes online, register a hardware breakpoint for the holder, avoiding races with watch_on()/watch_off() that may run on another CPU. The watch address will be updated the next time watch_on() is called. Signed-off-by: Jinchao Wang --- mm/kstackwatch/watch.c | 52 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 52 insertions(+) diff --git a/mm/kstackwatch/watch.c b/mm/kstackwatch/watch.c index 722ffd9fda7c..f32b1e46168c 100644 --- a/mm/kstackwatch/watch.c +++ b/mm/kstackwatch/watch.c @@ -89,6 +89,48 @@ static void ksw_watch_on_local_cpu(void *info) WARN(ret, "fail to reinstall HWBP on CPU%d ret %d", cpu, ret); } +static int ksw_watch_cpu_online(unsigned int cpu) +{ + struct perf_event_attr attr; + struct ksw_watchpoint *wp; + call_single_data_t *csd; + struct perf_event *bp; + + mutex_lock(&all_wp_mutex); + list_for_each_entry(wp, &all_wp_list, list) { + attr = wp->attr; + attr.bp_addr = (u64)&holder; + bp = perf_event_create_kernel_counter(&attr, cpu, NULL, + ksw_watch_handler, wp); + if (IS_ERR(bp)) { + pr_warn("%s failed to create watch on CPU %d: %ld\n", + __func__, cpu, PTR_ERR(bp)); + continue; + } + + per_cpu(*wp->event, cpu) = bp; + csd = per_cpu_ptr(wp->csd, cpu); + INIT_CSD(csd, ksw_watch_on_local_cpu, wp); + } + mutex_unlock(&all_wp_mutex); + return 0; +} + +static int ksw_watch_cpu_offline(unsigned int cpu) +{ + struct ksw_watchpoint *wp; + struct perf_event *bp; + + mutex_lock(&all_wp_mutex); + list_for_each_entry(wp, &all_wp_list, list) { + bp = per_cpu(*wp->event, cpu); + if (bp) + unregister_hw_breakpoint(bp); + } + mutex_unlock(&all_wp_mutex); + return 0; +} + static void ksw_watch_update(struct ksw_watchpoint *wp, ulong addr, u16 len) { call_single_data_t *csd; @@ -210,6 +252,16 @@ int ksw_watch_init(void) if (ret <= 0) return -EBUSY; + ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, + "kstackwatch:online", + ksw_watch_cpu_online, + ksw_watch_cpu_offline); + if (ret < 0) { + ksw_watch_free(); + pr_err("Failed to register CPU hotplug notifier\n"); + return ret; + } + return 0; } -- 2.43.0