From mboxrd@z Thu Jan 1 00:00:00 1970 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8F8E7C433F5 for ; Sat, 30 Oct 2021 12:23:54 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 068C461038 for ; Sat, 30 Oct 2021 12:23:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 068C461038 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=bytedance.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 48BBA940008; Sat, 30 Oct 2021 08:23:53 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 43B26940007; Sat, 30 Oct 2021 08:23:53 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 32A38940008; Sat, 30 Oct 2021 08:23:53 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0227.hostedemail.com [216.40.44.227]) by kanga.kvack.org (Postfix) with ESMTP id 23C86940007 for ; Sat, 30 Oct 2021 08:23:53 -0400 (EDT) Received: from smtpin09.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id C23A73A2A9 for ; Sat, 30 Oct 2021 12:23:52 +0000 (UTC) X-FDA: 78753020304.09.767E29A Received: from mail-yb1-f177.google.com (mail-yb1-f177.google.com [209.85.219.177]) by imf22.hostedemail.com (Postfix) with ESMTP id 9C6271900 for ; Sat, 30 Oct 2021 12:23:50 +0000 (UTC) Received: by mail-yb1-f177.google.com with SMTP id a6so31312656ybq.9 for ; Sat, 30 Oct 2021 05:23:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=5YtV6Ot0jonvatdmpLsBTlUfPHWMnjmg4fL8qYE8kh8=; b=HkhxAVHm2ETNFoCcDmD8TAiYQ59p7oUOP/GX/OwevsAZSm7FQdqD50kmazqxzoG/XO dfWM/zD3+m8BiVAop5p9sIkbJd+oy+311HQ8tv7mwhG+m4Kj9/mYdY3BSYvz7efKlmEf ML/9BTCjoJH/v8kQG/7meUYrYS9ImHJwx377dL4yWJes+1SeBaBoJD94C+sKNj6hHRux G2o/tZ41SCY+CR/doKnp/0Cu7MKVEIhR086qgRlS3365ckPaJrvI4Q0Q9lYcorC0i4zX 3RPfFv/9IIbQ5nSA1uSN5DiLKuifXt6wQnfCshv+wVUkq81ogKJxnIiqKFawg0C2fOkE eb4Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=5YtV6Ot0jonvatdmpLsBTlUfPHWMnjmg4fL8qYE8kh8=; b=JXRNDHNUCJYYZXwsJclSsRAvOEx0Cw5FRtjdLrXKyTdSXmaZw+NkfL60SpTIVM6Zud T5B9qDk1aorALrvFNLThP4x8IL6ch8FI28IlMuF4pE8hsSC+ZJYVmRrgw8wsqFFjLdr7 i2LbF8uk/GBwew/hRnWu9lBCNwWkTlYV/DhdvUm1k1D9Z9RciTBg9D/yBprxWetmCDTY ghU0qqGuREDBn7AkoG75BnX2M8/adIx0SU6giZesG3NxF1GbirefhEQVoruKCipHoaMz FoIUZePA7eHypLkRM0KdH/WVQanqrMg4sHK2g+9ela7d47b5dxWCSF4AMMqIWvitiUNU HDJw== X-Gm-Message-State: AOAM530TyHNYKC+sYCuRUG/xS4NAtho1wvnVc/7JdCn8wzhTF694PUSm 0mkWFRl9f2fXZhJUyMBkWVb07L+fYZmPoutalrszyg== X-Google-Smtp-Source: ABdhPJygShUOaRjn74sLxEG8tBRi+W3lqvbC+DVaQVq27wuJMONDctszG9FIwEb5qe/XXYIX830gQuAqPt7HgfTed4o= X-Received: by 2002:a25:59d5:: with SMTP id n204mr17770867ybb.189.1635596629841; Sat, 30 Oct 2021 05:23:49 -0700 (PDT) MIME-Version: 1.0 References: <867f6da4-6d38-6435-3fbb-a2a3744029f1@huawei.com> In-Reply-To: <867f6da4-6d38-6435-3fbb-a2a3744029f1@huawei.com> From: Muchun Song Date: Sat, 30 Oct 2021 20:23:12 +0800 Message-ID: Subject: Re: [PATCH] mm, slub: place the trace before freeing memory in kmem_cache_free() To: Yunfeng Ye Cc: Christoph Lameter , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , Vlastimil Babka , Linux Memory Management List , LKML , wuxu.wu@huawei.com, Hewenliang Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 9C6271900 X-Stat-Signature: xuucbghf3tmdjz5n9bu6jpn3bqwbzsks Authentication-Results: imf22.hostedemail.com; dkim=pass header.d=bytedance-com.20210112.gappssmtp.com header.s=20210112 header.b=HkhxAVHm; dmarc=pass (policy=none) header.from=bytedance.com; spf=pass (imf22.hostedemail.com: domain of songmuchun@bytedance.com designates 209.85.219.177 as permitted sender) smtp.mailfrom=songmuchun@bytedance.com X-HE-Tag: 1635596630-971714 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: On Sat, Oct 30, 2021 at 6:12 PM Yunfeng Ye wrote: > > After the memory is freed, it may be allocated by other CPUs and has > been recorded by trace. So the timing sequence of the memory tracing is > inaccurate. > > For example, we expect the following timing sequeuce: > > CPU 0 CPU 1 > > (1) alloc xxxxxx > (2) free xxxxxx > (3) alloc xxxxxx > (4) free xxxxxx > > However, the following timing sequence may occur: > > CPU 0 CPU 1 > > (1) alloc xxxxxx > (2) alloc xxxxxx > (3) free xxxxxx > (4) free xxxxxx > > So place the trace before freeing memory in kmem_cache_free(). Could you tell me what problem you have encountered here? Thanks. > > Signed-off-by: Yunfeng Ye > --- > mm/slub.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/slub.c b/mm/slub.c > index 432145d7b4ec..427e62034c3f 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -3526,8 +3526,8 @@ void kmem_cache_free(struct kmem_cache *s, void *x) > s = cache_from_obj(s, x); > if (!s) > return; > - slab_free(s, virt_to_head_page(x), x, NULL, 1, _RET_IP_); > trace_kmem_cache_free(_RET_IP_, x, s->name); > + slab_free(s, virt_to_head_page(x), x, NULL, 1, _RET_IP_); > } > EXPORT_SYMBOL(kmem_cache_free); > > -- > 2.27.0