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=-8.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable 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 36337C18E5B for ; Mon, 16 Mar 2020 15:45:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E9F5620679 for ; Mon, 16 Mar 2020 15:45:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="xASkp0EL" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731905AbgCPPpm (ORCPT ); Mon, 16 Mar 2020 11:45:42 -0400 Received: from mail-qk1-f194.google.com ([209.85.222.194]:41105 "EHLO mail-qk1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731715AbgCPPpm (ORCPT ); Mon, 16 Mar 2020 11:45:42 -0400 Received: by mail-qk1-f194.google.com with SMTP id s11so15637781qks.8 for ; Mon, 16 Mar 2020 08:45:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=iPNljTvaNQWCaWWd+vx+ooVAx+tFkyrnFRq/mDa1B3o=; b=xASkp0ELycx94keGFplut2ZJepIWff6JG29vLYTzBDCXELBqwOApx/O95qEZIpwLx6 rV6zcuHnLyKopl/05+nOQOjdSAkzg99WfxRqHERZPd36n1n1rinnnBGhMhZrEwT73txX Z1kFlSVIu46eiPzmOBPbOfL7zwI0MmgtRHMlQ= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=iPNljTvaNQWCaWWd+vx+ooVAx+tFkyrnFRq/mDa1B3o=; b=hUdokgsBlGccOAC1OsBR6ib426grzv/t3zmDhvg79Kj9RKe80OsEgBht25gsJAXMfH CqsEWn7SALrHl5DvLGwOkR+Q+sc3Up/USRg6OqVE93TDBSevHBQpXzEKQQ3nFHTiR4Mp eTyEmJc/UfLYxptHJy7q6IIfvkKZf5z8TqSAdi/nx6dBaq8vl3tr7kFCPWEn7m43WU0d rEMEa28VcrH6pOX8nB341QJEuqAzxfHRXjAgWKqGCHoTdSmCOevAlNy3cPYDb1tFHSV1 XYEQrTupSiX3gX+qNa1FM8ol5SBJA1X1gQyA+Tu0PeNXEltcPHHMtdMROsCR3bhYwevU tl8w== X-Gm-Message-State: ANhLgQ1yemMIhgmcr9CoGpmkkmXfAEbWaZHfmYkU0gkjpXio+xvYBs3h Ho0t0a2Wvs9O0oE4P57c4i5hxw== X-Google-Smtp-Source: ADFU+vsJMfZRY3mlCkPyTW2oKMTrq4Mr9dzfkEoKA2N+q+jThPaXqV1pJCzsoXMgRwiSP12fMLf6bw== X-Received: by 2002:a05:620a:21ce:: with SMTP id h14mr240002qka.363.1584373540502; Mon, 16 Mar 2020 08:45:40 -0700 (PDT) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id z18sm23887qtz.77.2020.03.16.08.45.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 16 Mar 2020 08:45:40 -0700 (PDT) Date: Mon, 16 Mar 2020 11:45:39 -0400 From: Joel Fernandes To: "Uladzislau Rezki (Sony)" Cc: LKML , "Paul E . McKenney" , RCU , Andrew Morton , Steven Rostedt , Oleksiy Avramchenko Subject: Re: [PATCH v1 2/6] rcu: introduce kvfree_rcu() interface Message-ID: <20200316154539.GE190951@google.com> References: <20200315181840.6966-1-urezki@gmail.com> <20200315181840.6966-3-urezki@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200315181840.6966-3-urezki@gmail.com> User-Agent: Mutt/1.12.2 (2019-09-21) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Mar 15, 2020 at 07:18:36PM +0100, Uladzislau Rezki (Sony) wrote: > kvfree_rcu() can deal with an allocated memory that is obtained > via kvmalloc(). It can return two types of allocated memory or > "pointers", one can belong to regular SLAB allocator and another > one can be vmalloc one. It depends on requested size and memory > pressure. > > Based on that, two streams are split, thus if a pointer belongs > to vmalloc allocator it is queued to the list, otherwise SLAB > one is queued into "bulk array" for further processing. > > The main reason of such splitting is: > a) to distinguish kmalloc()/vmalloc() ptrs; > b) there is no vmalloc_bulk() interface. > > As of now we have list_lru.c user that needs such interface, > also there will be new comers. Apart of that it is preparation > to have a head-less variant later. > > Signed-off-by: Uladzislau Rezki (Sony) > --- > include/linux/rcupdate.h | 9 +++++++++ > kernel/rcu/tiny.c | 3 ++- > kernel/rcu/tree.c | 17 ++++++++++++----- > 3 files changed, 23 insertions(+), 6 deletions(-) > > diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h > index 2be97a83f266..bb270221dbdc 100644 > --- a/include/linux/rcupdate.h > +++ b/include/linux/rcupdate.h > @@ -845,6 +845,15 @@ do { \ > __kfree_rcu(&((___p)->rhf), offsetof(typeof(*(ptr)), rhf)); \ > } while (0) > > +/** > + * kvfree_rcu() - kvfree an object after a grace period. > + * @ptr: pointer to kvfree > + * @rhf: the name of the struct rcu_head within the type of @ptr. > + * > + * Same as kfree_rcu(), just simple alias. > + */ > +#define kvfree_rcu(ptr, rhf) kfree_rcu(ptr, rhf) > + > /* > * Place this after a lock-acquisition primitive to guarantee that > * an UNLOCK+LOCK pair acts as a full barrier. This guarantee applies > diff --git a/kernel/rcu/tiny.c b/kernel/rcu/tiny.c > index dd572ce7c747..4b99f7b88bee 100644 > --- a/kernel/rcu/tiny.c > +++ b/kernel/rcu/tiny.c > @@ -23,6 +23,7 @@ > #include > #include > #include > +#include > > #include "rcu.h" > > @@ -86,7 +87,7 @@ static inline bool rcu_reclaim_tiny(struct rcu_head *head) > rcu_lock_acquire(&rcu_callback_map); > if (__is_kfree_rcu_offset(offset)) { > trace_rcu_invoke_kfree_callback("", head, offset); > - kfree((void *)head - offset); > + kvfree((void *)head - offset); > rcu_lock_release(&rcu_callback_map); > return true; > } > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 2f4c91a3713a..1c0a73616872 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -2899,9 +2899,9 @@ static void kfree_rcu_work(struct work_struct *work) > } > > /* > - * Emergency case only. It can happen under low memory > - * condition when an allocation gets failed, so the "bulk" > - * path can not be temporary maintained. > + * vmalloc() pointers end up here also emergency case. It can Suggest rephrase for clarity: nit: We can end up here either with 1) vmalloc() pointers or 2) low on memory and could not allocate a bulk array. thanks, - Joel > + * happen under low memory condition when an allocation gets > + * failed, so the "bulk" path can not be temporary maintained. > */ > for (; head; head = next) { > unsigned long offset = (unsigned long)head->func; > @@ -2912,7 +2912,7 @@ static void kfree_rcu_work(struct work_struct *work) > trace_rcu_invoke_kfree_callback(rcu_state.name, head, offset); > > if (!WARN_ON_ONCE(!__is_kfree_rcu_offset(offset))) > - kfree((void *)head - offset); > + kvfree((void *)head - offset); > > rcu_lock_release(&rcu_callback_map); > cond_resched_tasks_rcu_qs(); > @@ -3084,10 +3084,17 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > } > > /* > + * We do not queue vmalloc pointers into array, > + * instead they are just queued to the list. We > + * do it because of: > + * a) to distinguish kmalloc()/vmalloc() ptrs; > + * b) there is no vmalloc_bulk() interface. > + * > * Under high memory pressure GFP_NOWAIT can fail, > * in that case the emergency path is maintained. > */ > - if (unlikely(!kfree_call_rcu_add_ptr_to_bulk(krcp, head, func))) { > + if (is_vmalloc_addr((void *) head - (unsigned long) func) || > + !kfree_call_rcu_add_ptr_to_bulk(krcp, head, func)) { > head->func = func; > head->next = krcp->head; > krcp->head = head; > -- > 2.20.1 >