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Mon, 10 Nov 2025 08:37:25 -0800 (PST) From: Jinchao Wang To: Andrew Morton , "Masami Hiramatsu (Google)" , Peter Zijlstra , Randy Dunlap , Marco Elver , Mike Rapoport , Alexander Potapenko , Adrian Hunter , Alexander Shishkin , Alice Ryhl , Andrey Konovalov , Andrey Ryabinin , Andrii Nakryiko , Ard Biesheuvel , Arnaldo Carvalho de Melo , Ben Segall , Bill Wendling , Borislav Petkov , Catalin Marinas , Dave Hansen , David Hildenbrand , David Kaplan , "David S. Miller" , Dietmar Eggemann , Dmitry Vyukov , "H. Peter Anvin" , Ian Rogers , Ingo Molnar , James Clark , Jinchao Wang , Jinjie Ruan , Jiri Olsa , Jonathan Corbet , Juri Lelli , Justin Stitt , kasan-dev@googlegroups.com, Kees Cook , "Liam R. Howlett" , "Liang Kan" , Linus Walleij , linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-perf-users@vger.kernel.org, linux-trace-kernel@vger.kernel.org, llvm@lists.linux.dev, Lorenzo Stoakes , Mark Rutland , Masahiro Yamada , Mathieu Desnoyers , Mel Gorman , Michal Hocko , Miguel Ojeda , Nam Cao , Namhyung Kim , Nathan Chancellor , Naveen N Rao , Nick Desaulniers , Rong Xu , Sami Tolvanen , Steven Rostedt , Suren Baghdasaryan , Thomas Gleixner , =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= , Valentin Schneider , Vincent Guittot , Vincenzo Frascino , Vlastimil Babka , Will Deacon , workflows@vger.kernel.org, x86@kernel.org Subject: [PATCH v8 10/27] mm/ksw: support CPU hotplug Date: Tue, 11 Nov 2025 00:36:05 +0800 Message-ID: <20251110163634.3686676-11-wangjinchao600@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20251110163634.3686676-1-wangjinchao600@gmail.com> References: <20251110163634.3686676-1-wangjinchao600@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: DF17740012 X-Stat-Signature: ttcxshmf3tr5159yrswpxsrja9bwhjpk X-HE-Tag: 1762792646-143944 X-HE-Meta: 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 /gDsAB2U 6M/JUAM2/tcUByAsBCXzyQGgITFlS3ZdDImdaP5NoZsWf233uHPu4KeMi4GNvhLwpJXru1pon17gKIKOgWgiGEieX9pHKwOpcFISBqfeO6UIljrTetfIbmZcLbw/NNQKa7G9v24IZCYApP80PSgfW+qedGELQMgSYBsdulCL3R4mIlYe36jhplJPGe6ue6MHBsjwDeJNoI236y1tQhKTf/4987OfxosOuBIDAqWo38y87ccr4WVERBrRvLE8yGQTMWxDIZFG4O1vaeETO296LqLCFJrzPfLvFq46muAyFkuvR8R9aPdnIZGWTGCyf7kpOhJTWiOpyHRiFTI8kdSsKKI6VWtHFrUp5Fv9kjtLX0JF0nLSgAdnSbBIwwQCZi75kIRsYCrFqXdKUPVrNBXmvq7N70H5n52uDQO29A9/QSZRdWGq1V5lv2qEbhvwHOXby9CLVgwymdYyLqsVxqJitHk37BTN+gHSZR7pLrQLuo44UKSndfBQ8MDsI45JfF+FHULGYfZNiVc2Jj7IvKHiYrV00orRY/tCFvNsf/PHBONMuBh/47LsmPcKFKCslj+E/elDyPke0vLukEJHsxGK5blU+CQ== 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 f922b4164be5..99184f63d7e3 100644 --- a/mm/kstackwatch/watch.c +++ b/mm/kstackwatch/watch.c @@ -85,6 +85,48 @@ 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; @@ -206,6 +248,16 @@ 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