From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ej1-f74.google.com (mail-ej1-f74.google.com [209.85.218.74]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 88BE0E541 for ; Mon, 15 Jan 2024 09:27:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--elver.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="JzwcuDlH" Received: by mail-ej1-f74.google.com with SMTP id a640c23a62f3a-a2daab7f775so31014966b.2 for ; Mon, 15 Jan 2024 01:27:34 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1705310852; x=1705915652; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=bmhCfln9ac1sszz1cn9mo233ZA1ZqqWQM/ks4o+Avbk=; b=JzwcuDlHyfuflMWO07WxWr4rEq2cJMl5H9i+nxg1L4O8wFoutdveUsA60/LUnnS9IZ Ds2p902XKJIVw4TOM/GQoP7eoxJ+2ImglcWhhzNSg/CQXbrGRdLdiCv05jZW5CdJEIar esY5c1h8Dj+MuA+Pd1Xgvhh+2LpNo2Ye0P1u33mCEVPgbn9owXEF2kZRs4fG3cZ2HdgE sxx3Ln/IBmfV0f63lscVP0jFHVDdTyB7O4uZQ5Oim7rHDalrQBWb1mqyTCEgRisCcuPS zr7DRJRUqog1j0c6sJapYH9aZCOfMmc7mD0GyjiD9edjepMyxXemXSq1po0a+5vu1ow7 eUIQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1705310852; x=1705915652; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=bmhCfln9ac1sszz1cn9mo233ZA1ZqqWQM/ks4o+Avbk=; b=o/JXsJbJkg9R0AX+vfoJk2MxM1RZsPwJAmfd80n5XCWmTVQyQO/4AQaDU2cYhB1Vgy e4eYYMi4Cq4fbxRKROYLV1LtdFqZwfqP8SLd2NM3HQUocv7qZ/gTifGN+e86tD71YzHl 56yvMre9VMtAFpdu7v2sNJ4CxGs8+X564w86LvxIAEDKVeYSD2uELRY65zK1Ge0DkkEI Oj3jVGD7DoOZTBLLdVrImfCk4AVmfy2681Ch8B0rXDFn/q0ZUzluPMwsduQxVh2dnnGL nNqGYN79/uUMnIUy5iq4Y/AzmyhFq2IxqiZFHFnPsXcthaB6Pw53CCkjI81dJMj/zzHM ZsDg== X-Gm-Message-State: AOJu0YzzSixfMmLV/hvr2PLsPJ3VWbhKEbilZuj6plawSCDYEh8ZB1am lAkhxa5Q9+FxaY2Pfa8JhkgW7Xr8AZ16uLrG X-Google-Smtp-Source: AGHT+IFO5G17Z/aSbnFl1izEtytTzjyDHPAC2GSkCyKOxlkJnXKbs6uNSZNVR1ANbd4JIGqvNlRpR+vZ4Q== X-Received: from elver.muc.corp.google.com ([2a00:79e0:9c:201:38c7:85d7:36f7:e198]) (user=elver job=sendgmr) by 2002:a17:906:54a:b0:a2c:7164:ff8d with SMTP id k10-20020a170906054a00b00a2c7164ff8dmr38908eja.3.1705310852357; Mon, 15 Jan 2024 01:27:32 -0800 (PST) Date: Mon, 15 Jan 2024 10:27:18 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.43.0.275.g3460e3d667-goog Message-ID: <20240115092727.888096-1-elver@google.com> Subject: [PATCH RFC 1/2] stackdepot: add stats counters exported via debugfs From: Marco Elver To: elver@google.com, Andrew Morton Cc: Andrey Konovalov , Alexander Potapenko , Dmitry Vyukov , Vlastimil Babka , linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com Content-Type: text/plain; charset="UTF-8" Add a few basic stats counters for stack depot that can be used to derive if stack depot is working as intended. This is a snapshot of the new stats after booting a system with a KASAN-enabled kernel: $ cat /sys/kernel/debug/stackdepot/stats pools: 838 allocations: 29861 frees: 6561 in_use: 23300 freelist_size: 1840 Generally, "pools" should be well below the max; once the system is booted, "in_use" should remain relatively steady. Signed-off-by: Marco Elver --- lib/stackdepot.c | 53 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) diff --git a/lib/stackdepot.c b/lib/stackdepot.c index a0be5d05c7f0..80a8ca24ccc8 100644 --- a/lib/stackdepot.c +++ b/lib/stackdepot.c @@ -14,6 +14,7 @@ #define pr_fmt(fmt) "stackdepot: " fmt +#include #include #include #include @@ -115,6 +116,23 @@ static bool new_pool_required = true; /* Lock that protects the variables above. */ static DEFINE_RWLOCK(pool_rwlock); +/* Statistics counters for debugfs. */ +enum depot_counter_id { + DEPOT_COUNTER_ALLOCS, + DEPOT_COUNTER_FREES, + DEPOT_COUNTER_INUSE, + DEPOT_COUNTER_FREELIST_SIZE, + DEPOT_COUNTER_COUNT, +}; +static long counters[DEPOT_COUNTER_COUNT]; +static const char *const counter_names[] = { + [DEPOT_COUNTER_ALLOCS] = "allocations", + [DEPOT_COUNTER_FREES] = "frees", + [DEPOT_COUNTER_INUSE] = "in_use", + [DEPOT_COUNTER_FREELIST_SIZE] = "freelist_size", +}; +static_assert(ARRAY_SIZE(counter_names) == DEPOT_COUNTER_COUNT); + static int __init disable_stack_depot(char *str) { return kstrtobool(str, &stack_depot_disabled); @@ -277,6 +295,7 @@ static void depot_init_pool(void *pool) stack->handle.extra = 0; list_add(&stack->list, &free_stacks); + counters[DEPOT_COUNTER_FREELIST_SIZE]++; } /* Save reference to the pool to be used by depot_fetch_stack(). */ @@ -376,6 +395,7 @@ depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc) /* Get and unlink the first entry from the freelist. */ stack = list_first_entry(&free_stacks, struct stack_record, list); list_del(&stack->list); + counters[DEPOT_COUNTER_FREELIST_SIZE]--; /* Limit number of saved frames to CONFIG_STACKDEPOT_MAX_FRAMES. */ if (size > CONFIG_STACKDEPOT_MAX_FRAMES) @@ -394,6 +414,8 @@ depot_alloc_stack(unsigned long *entries, int size, u32 hash, void **prealloc) */ kmsan_unpoison_memory(stack, DEPOT_STACK_RECORD_SIZE); + counters[DEPOT_COUNTER_ALLOCS]++; + counters[DEPOT_COUNTER_INUSE]++; return stack; } @@ -426,6 +448,10 @@ static void depot_free_stack(struct stack_record *stack) lockdep_assert_held_write(&pool_rwlock); list_add(&stack->list, &free_stacks); + + counters[DEPOT_COUNTER_FREELIST_SIZE]++; + counters[DEPOT_COUNTER_FREES]++; + counters[DEPOT_COUNTER_INUSE]--; } /* Calculates the hash for a stack. */ @@ -690,3 +716,30 @@ unsigned int stack_depot_get_extra_bits(depot_stack_handle_t handle) return parts.extra; } EXPORT_SYMBOL(stack_depot_get_extra_bits); + +static int stats_show(struct seq_file *seq, void *v) +{ + /* + * data race ok: These are just statistics counters, and approximate + * statistics are ok for debugging. + */ + seq_printf(seq, "pools: %d\n", data_race(pools_num)); + for (int i = 0; i < DEPOT_COUNTER_COUNT; i++) + seq_printf(seq, "%s: %ld\n", counter_names[i], data_race(counters[i])); + + return 0; +} +DEFINE_SHOW_ATTRIBUTE(stats); + +static int depot_debugfs_init(void) +{ + struct dentry *dir; + + if (stack_depot_disabled) + return 0; + + dir = debugfs_create_dir("stackdepot", NULL); + debugfs_create_file("stats", 0444, dir, NULL, &stats_fops); + return 0; +} +late_initcall(depot_debugfs_init); -- 2.43.0.275.g3460e3d667-goog