From patchwork Thu Sep 23 10:48:00 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Marco Elver X-Patchwork-Id: 12512397 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6B1AAC433F5 for ; Thu, 23 Sep 2021 10:48:17 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id E6E7C60EE7 for ; Thu, 23 Sep 2021 10:48:16 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org E6E7C60EE7 Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 8408E6B0071; Thu, 23 Sep 2021 06:48:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7F0B06B0072; Thu, 23 Sep 2021 06:48:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6DFD3900002; Thu, 23 Sep 2021 06:48:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0213.hostedemail.com [216.40.44.213]) by kanga.kvack.org (Postfix) with ESMTP id 601BF6B0071 for ; Thu, 23 Sep 2021 06:48:16 -0400 (EDT) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 14A022FD9C for ; Thu, 23 Sep 2021 10:48:16 +0000 (UTC) X-FDA: 78618513792.10.FEB9E59 Received: from mail-wr1-f74.google.com (mail-wr1-f74.google.com [209.85.221.74]) by imf17.hostedemail.com (Postfix) with ESMTP id CEBF8F00038C for ; Thu, 23 Sep 2021 10:48:15 +0000 (UTC) Received: by mail-wr1-f74.google.com with SMTP id r7-20020a5d6947000000b0015e0f68a63bso4756483wrw.22 for ; Thu, 23 Sep 2021 03:48:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=fWJbOvO/9IQd66CKXhWeX2UUgjmgk+7Ytnnk5fprUlg=; b=YK7pY2T3iaVC5xj3yZsnws4HJRmKJ1x8OmasO4WGgABT7rft/ZvQs4eh1gFpy8QetD 9KFo7eg38M1OU0JT69layBKo4st3huLUeepUVwNfVluaA7bxQ+sTdPwn6Xevo9ThbnmG jQQDmsU1F8ePO39RpE0bTfH97J7YRmeHXWGwGY2IhhhojpcORagCJnt8penB7I+v9yDj 7vilSsCePqG+aodTc6Az7A1RmmZbD9Vzq1m1U9a/xZF4rtFOXa2naUGI9rjT2fthCoV/ pH3tfvOHyvmn/yr6p+nVHw10RJ8IsJ5icn8k/qTaMN0WdIIt56ezcaixdz8RC479uBXQ gS3Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=fWJbOvO/9IQd66CKXhWeX2UUgjmgk+7Ytnnk5fprUlg=; b=dEt2NNq1v/3tSJjWL12Ca+oPu7AlPyoECZCbLxkUcfcLkI3Lp0751dcN2MmKR3YYOD K0nLZ0gsKITjm2jnEGvF6w1ah0INfNH15AUHSCpsO8Gw5K6xd6NiBGNXoCSl9sSZA/CX R2m0q5rm9z6cyTbh6y7a7+GvErxEe9JQWFYkw1zTfvqRAjAbNEE4kcxw9RmiNAxvOerd MBXPj/z5TOpxvawhOE4qDe5otPMGEjp+5jWWp7h+bBrXepxzfzpgHcAcyAdj1tKG9fDx UnV1PCabVCC9HXUhHOWdda3fgTO69GBvZxSZZe/C2u40mXQSs3dF8vfqZu7fqcorB0am q+AQ== X-Gm-Message-State: AOAM530/O60KK89R6/diCT4kTus70JyIQmwWsnP3TsY5g8wgxOlxZMth /fU/mjpCB1zls0Kh2U9wpwfzUEUwQw== X-Google-Smtp-Source: ABdhPJww9Oj32004rlHlbgMaoG0LRo/rz6EFbKkPl4dyYvsN1SYDd8AmtefGBVYLegGFwkMLj0o33H8J5w== X-Received: from elver.muc.corp.google.com ([2a00:79e0:15:13:bd72:fd35:a085:c2e3]) (user=elver job=sendgmr) by 2002:a05:600c:4154:: with SMTP id h20mr15186317wmm.172.1632394094273; Thu, 23 Sep 2021 03:48:14 -0700 (PDT) Date: Thu, 23 Sep 2021 12:48:00 +0200 In-Reply-To: <20210923104803.2620285-1-elver@google.com> Message-Id: <20210923104803.2620285-2-elver@google.com> Mime-Version: 1.0 References: <20210923104803.2620285-1-elver@google.com> X-Mailer: git-send-email 2.33.0.464.g1972c5931b-goog Subject: [PATCH v3 2/5] kfence: count unexpectedly skipped allocations From: Marco Elver To: elver@google.com, Andrew Morton Cc: Alexander Potapenko , Dmitry Vyukov , Jann Horn , Aleksandr Nogikh , Taras Madan , linux-kernel@vger.kernel.org, linux-mm@kvack.org, kasan-dev@googlegroups.com X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: CEBF8F00038C X-Stat-Signature: nuc3m95fg36dq1cg6wae49nod6jtno5z Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=YK7pY2T3; spf=pass (imf17.hostedemail.com: domain of 3bltMYQUKCGcJQaJWLTTLQJ.HTRQNSZc-RRPaFHP.TWL@flex--elver.bounces.google.com designates 209.85.221.74 as permitted sender) smtp.mailfrom=3bltMYQUKCGcJQaJWLTTLQJ.HTRQNSZc-RRPaFHP.TWL@flex--elver.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com X-HE-Tag: 1632394095-717136 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: Maintain a counter to count allocations that are skipped due to being incompatible (oversized, incompatible gfp flags) or no capacity. This is to compute the fraction of allocations that could not be serviced by KFENCE, which we expect to be rare. Signed-off-by: Marco Elver Reviewed-by: Dmitry Vyukov Acked-by: Alexander Potapenko --- v2: * Do not count deadlock-avoidance skips. --- mm/kfence/core.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/mm/kfence/core.c b/mm/kfence/core.c index 7a97db8bc8e7..249d75b7e5ee 100644 --- a/mm/kfence/core.c +++ b/mm/kfence/core.c @@ -112,6 +112,8 @@ enum kfence_counter_id { KFENCE_COUNTER_FREES, KFENCE_COUNTER_ZOMBIES, KFENCE_COUNTER_BUGS, + KFENCE_COUNTER_SKIP_INCOMPAT, + KFENCE_COUNTER_SKIP_CAPACITY, KFENCE_COUNTER_COUNT, }; static atomic_long_t counters[KFENCE_COUNTER_COUNT]; @@ -121,6 +123,8 @@ static const char *const counter_names[] = { [KFENCE_COUNTER_FREES] = "total frees", [KFENCE_COUNTER_ZOMBIES] = "zombie allocations", [KFENCE_COUNTER_BUGS] = "total bugs", + [KFENCE_COUNTER_SKIP_INCOMPAT] = "skipped allocations (incompatible)", + [KFENCE_COUNTER_SKIP_CAPACITY] = "skipped allocations (capacity)", }; static_assert(ARRAY_SIZE(counter_names) == KFENCE_COUNTER_COUNT); @@ -271,8 +275,10 @@ static void *kfence_guarded_alloc(struct kmem_cache *cache, size_t size, gfp_t g list_del_init(&meta->list); } raw_spin_unlock_irqrestore(&kfence_freelist_lock, flags); - if (!meta) + if (!meta) { + atomic_long_inc(&counters[KFENCE_COUNTER_SKIP_CAPACITY]); return NULL; + } if (unlikely(!raw_spin_trylock_irqsave(&meta->lock, flags))) { /* @@ -740,8 +746,10 @@ void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags) * Perform size check before switching kfence_allocation_gate, so that * we don't disable KFENCE without making an allocation. */ - if (size > PAGE_SIZE) + if (size > PAGE_SIZE) { + atomic_long_inc(&counters[KFENCE_COUNTER_SKIP_INCOMPAT]); return NULL; + } /* * Skip allocations from non-default zones, including DMA. We cannot @@ -749,8 +757,10 @@ void *__kfence_alloc(struct kmem_cache *s, size_t size, gfp_t flags) * properties (e.g. reside in DMAable memory). */ if ((flags & GFP_ZONEMASK) || - (s->flags & (SLAB_CACHE_DMA | SLAB_CACHE_DMA32))) + (s->flags & (SLAB_CACHE_DMA | SLAB_CACHE_DMA32))) { + atomic_long_inc(&counters[KFENCE_COUNTER_SKIP_INCOMPAT]); return NULL; + } /* * allocation_gate only needs to become non-zero, so it doesn't make