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 X-Spam-Level: X-Spam-Status: No, score=-11.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_IN_DEF_DKIM_WL autolearn=no 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 6D007C3F68F for ; Fri, 17 Jan 2020 20:54:57 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 34A5A2072B for ; Fri, 17 Jan 2020 20:54:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="tkFfa4iF" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 34A5A2072B Authentication-Results: mail.kernel.org; dmarc=fail (p=reject dis=none) header.from=google.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id BB7226B04EB; Fri, 17 Jan 2020 15:54:56 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B67756B04EC; Fri, 17 Jan 2020 15:54:56 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A7D166B04ED; Fri, 17 Jan 2020 15:54:56 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0084.hostedemail.com [216.40.44.84]) by kanga.kvack.org (Postfix) with ESMTP id 927BA6B04EB for ; Fri, 17 Jan 2020 15:54:56 -0500 (EST) Received: from smtpin29.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with SMTP id 2925F181AEF1F for ; Fri, 17 Jan 2020 20:54:56 +0000 (UTC) X-FDA: 76388330592.29.roof82_48281df169e57 X-HE-Tag: roof82_48281df169e57 X-Filterd-Recvd-Size: 3986 Received: from mail-oi1-f195.google.com (mail-oi1-f195.google.com [209.85.167.195]) by imf48.hostedemail.com (Postfix) with ESMTP for ; Fri, 17 Jan 2020 20:54:55 +0000 (UTC) Received: by mail-oi1-f195.google.com with SMTP id n16so23401846oie.12 for ; Fri, 17 Jan 2020 12:54:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=EpP4mR6++ym0+clDqbbYwXk+no5QrN1xJrvrHjjjmE0=; b=tkFfa4iFAd+jroP8t34rOqeszZpg427nMtkcpusKGMgHGjCefWrryEVOMtujEljy5/ 8qBfL2I8nyxfFuvhe/AtgEqDVAn0fOBwJzcjvISKvZpsWdqQOMYAy4KFak70JS1HnX0k elDvn2zKcpoEAm/I3kWJUSLN2S9YnOUpZQzhBdlIP5T1rJ8K6heSdC74uqdp4dLrYHh/ E+GO6qgTMLJmm4mkIcxWxuGKdiD6gBbOfb/+2Eo2iBSTeGy1m/7p986Xh/aVF3TEfiyy Sr9KhWjSN6L+WeraAo09KnX44N7Jyvu7HM4PrYeh5dpGq3AvahTuDNE49oZkOyTC4C/w 06aw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=EpP4mR6++ym0+clDqbbYwXk+no5QrN1xJrvrHjjjmE0=; b=ZopnlAdrjCfTVM+lSmo+FJIDZsjo2vK0cnlQB/3RuYadx8uqHgaw9m622cZYzKbStw jeOW/QGJ8Pbz/t/0KA7534MXkaswSx+E0I2+EfzYMRWd/CEWph9FH1OBhdlejldWZuU8 hAXdRY88zco/Fi3So5Cz1pdkv04qRn4F3iYTdhqacifio2UfKypCXU/I7TYui0a5M0q9 DP+DfWd6Yy2D73tIDM3cSd/Z27WbItL6tuWCmqoSFd6twnHlSeIWbn7HwwajgBrB8SUw rUwXmg4KPwFRHlKji3c/S0zDCkmfInr7jc1FAmXDejqkyuHRl0Bkpsp6UOAmpttS+ITE xqXg== X-Gm-Message-State: APjAAAVDWqGfo8hE26Vwue0qtkQ8qwjdBfI0A3Lx4SUMvw9lPB06uO+2 HXX/Q26pPbaOcYk8Kg9VT7KglzGCT/8Q9pTWLmt7Cw== X-Google-Smtp-Source: APXvYqyzdxUUBvm+6osC1RRrqdzxgenbyaoz4CMFFZqjH6owgPtbnJZKARkwMewNMJ70ydOGsHL3POvx59nMEwed01M= X-Received: by 2002:aca:3cd7:: with SMTP id j206mr4978548oia.142.1579294494766; Fri, 17 Jan 2020 12:54:54 -0800 (PST) MIME-Version: 1.0 References: <20200117203609.3146239-1-guro@fb.com> In-Reply-To: <20200117203609.3146239-1-guro@fb.com> From: Shakeel Butt Date: Fri, 17 Jan 2020 12:54:43 -0800 Message-ID: Subject: Re: [PATCH] mm: memcg/slab: introduce mem_cgroup_from_obj() To: Roman Gushchin Cc: Linux MM , Andrew Morton , Michal Hocko , Johannes Weiner , Vladimir Davydov , LKML , Kernel Team , Yafang Shao Content-Type: text/plain; charset="UTF-8" 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 Fri, Jan 17, 2020 at 12:36 PM Roman Gushchin wrote: > > Sometimes we need to get a memcg pointer from a charged kernel object. > The right way to get it depends on whether it's a proper slab object > or it's backed by raw pages (e.g. it's a vmalloc alloction). In the > first case the kmem_cache->memcg_params.memcg indirection should be > used; in other cases it's just page->mem_cgroup. > > To simplify this task and hide the implementation details let's > introduce a mem_cgroup_from_obj() helper, which takes a pointer > to any kernel object and returns a valid memcg pointer or NULL. > > Passing a kernel address rather than a pointer to a page will allow > to use this helper for per-object (rather than per-page) tracked > objects in the future. > > The caller is still responsible to ensure that the returned memcg > isn't going away underneath: take the rcu read lock, cgroup mutex etc; > depending on the context. > > mem_cgroup_from_kmem() defined in mm/list_lru.c is now obsolete > and can be removed. > > Signed-off-by: Roman Gushchin > Acked-by: Yafang Shao Reviewed-by: Shakeel Butt