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Thu, 09 Oct 2025 03:57:46 -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 v7 10/23] mm/ksw: support CPU hotplug Date: Thu, 9 Oct 2025 18:55:46 +0800 Message-ID: <20251009105650.168917-11-wangjinchao600@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251009105650.168917-1-wangjinchao600@gmail.com> References: <20251009105650.168917-1-wangjinchao600@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Queue-Id: 4CC2514000F X-Rspamd-Server: rspam11 X-Rspam-User: X-Stat-Signature: k4cf7t4rh4sucutu7zmkp93nzxk581i3 X-HE-Tag: 1760007468-608017 X-HE-Meta: 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 uReaGh1c 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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