From patchwork Tue Mar 22 21:48:10 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 12789274 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 80282C433EF for ; Tue, 22 Mar 2022 21:48:13 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 165EE6B01A0; Tue, 22 Mar 2022 17:48:13 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0F0046B01A1; Tue, 22 Mar 2022 17:48:13 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EF8086B01A2; Tue, 22 Mar 2022 17:48:12 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0144.hostedemail.com [216.40.44.144]) by kanga.kvack.org (Postfix) with ESMTP id DCF186B01A0 for ; Tue, 22 Mar 2022 17:48:12 -0400 (EDT) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id 9B50C1828AE2E for ; Tue, 22 Mar 2022 21:48:12 +0000 (UTC) X-FDA: 79273360824.30.5173F27 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf16.hostedemail.com (Postfix) with ESMTP id 25CA418002A for ; Tue, 22 Mar 2022 21:48:12 +0000 (UTC) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 8FCC16174B; Tue, 22 Mar 2022 21:48:11 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id EAFBDC340EC; Tue, 22 Mar 2022 21:48:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1647985691; bh=qj3zkiXxH1lU5fnTBu/L7vSbRLdo2ycVZo2tH+WdVpM=; h=Date:To:From:In-Reply-To:Subject:From; b=LR882vkSSqVZA695slKuGBExxDqoPHEq7KAyX0mlx3ISh0GAC7/VD3h9rnDl1k6L0 cj20z3MnYDnwHMek9DHku9QXYWcXZ5/mqc+ozGREDn1+bTBcQDttD+WKAgEGcsHxyq 05A70Z0B0F59kdkgZJS9PViinQrsAHL67cGonIb4= Date: Tue, 22 Mar 2022 14:48:10 -0700 To: glider@google.com,elver@google.com,dvyukov@google.com,dtcccc@linux.alibaba.com,akpm@linux-foundation.org,patches@lists.linux.dev,linux-mm@kvack.org,mm-commits@vger.kernel.org,torvalds@linux-foundation.org,akpm@linux-foundation.org From: Andrew Morton In-Reply-To: <20220322143803.04a5e59a07e48284f196a2f9@linux-foundation.org> Subject: [patch 190/227] kfence: allow re-enabling KFENCE after system startup Message-Id: <20220322214810.EAFBDC340EC@smtp.kernel.org> X-Rspam-User: Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=LR882vkS; spf=pass (imf16.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 25CA418002A X-Stat-Signature: kr3gkkiwnushz9nx9bxpfq5acqruzufo X-HE-Tag: 1647985692-315459 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: From: Tianchen Ding Subject: kfence: allow re-enabling KFENCE after system startup Patch series "provide the flexibility to enable KFENCE", v3. If CONFIG_CONTIG_ALLOC is not supported, we fallback to try alloc_pages_exact(). Allocating pages in this way has limits about MAX_ORDER (default 11). So we will not support allocating kfence pool after system startup with a large KFENCE_NUM_OBJECTS. When handling failures in kfence_init_pool_late(), we pair free_pages_exact() to alloc_pages_exact() for compatibility consideration, though it actually does the same as free_contig_range(). This patch (of 2): If once KFENCE is disabled by: echo 0 > /sys/module/kfence/parameters/sample_interval KFENCE could never be re-enabled until next rebooting. Allow re-enabling it by writing a positive num to sample_interval. Link: https://lkml.kernel.org/r/20220307074516.6920-1-dtcccc@linux.alibaba.com Link: https://lkml.kernel.org/r/20220307074516.6920-2-dtcccc@linux.alibaba.com Signed-off-by: Tianchen Ding Reviewed-by: Marco Elver Cc: Alexander Potapenko Cc: Dmitry Vyukov Signed-off-by: Andrew Morton --- mm/kfence/core.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-) --- a/mm/kfence/core.c~kfence-allow-re-enabling-kfence-after-system-startup +++ a/mm/kfence/core.c @@ -38,14 +38,17 @@ #define KFENCE_WARN_ON(cond) \ ({ \ const bool __cond = WARN_ON(cond); \ - if (unlikely(__cond)) \ + if (unlikely(__cond)) { \ WRITE_ONCE(kfence_enabled, false); \ + disabled_by_warn = true; \ + } \ __cond; \ }) /* === Data ================================================================= */ static bool kfence_enabled __read_mostly; +static bool disabled_by_warn __read_mostly; unsigned long kfence_sample_interval __read_mostly = CONFIG_KFENCE_SAMPLE_INTERVAL; EXPORT_SYMBOL_GPL(kfence_sample_interval); /* Export for test modules. */ @@ -55,6 +58,7 @@ EXPORT_SYMBOL_GPL(kfence_sample_interval #endif #define MODULE_PARAM_PREFIX "kfence." +static int kfence_enable_late(void); static int param_set_sample_interval(const char *val, const struct kernel_param *kp) { unsigned long num; @@ -65,10 +69,11 @@ static int param_set_sample_interval(con if (!num) /* Using 0 to indicate KFENCE is disabled. */ WRITE_ONCE(kfence_enabled, false); - else if (!READ_ONCE(kfence_enabled) && system_state != SYSTEM_BOOTING) - return -EINVAL; /* Cannot (re-)enable KFENCE on-the-fly. */ *((unsigned long *)kp->arg) = num; + + if (num && !READ_ONCE(kfence_enabled) && system_state != SYSTEM_BOOTING) + return disabled_by_warn ? -EINVAL : kfence_enable_late(); return 0; } @@ -787,6 +792,16 @@ void __init kfence_init(void) (void *)(__kfence_pool + KFENCE_POOL_SIZE)); } +static int kfence_enable_late(void) +{ + if (!__kfence_pool) + return -EINVAL; + + WRITE_ONCE(kfence_enabled, true); + queue_delayed_work(system_unbound_wq, &kfence_timer, 0); + return 0; +} + void kfence_shutdown_cache(struct kmem_cache *s) { unsigned long flags;