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=-17.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 0D078C4361B for ; Wed, 9 Dec 2020 19:46:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BC2E323C8F for ; Wed, 9 Dec 2020 19:46:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731932AbgLITn1 (ORCPT ); Wed, 9 Dec 2020 14:43:27 -0500 Received: from mail.kernel.org ([198.145.29.99]:43344 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387873AbgLITnU (ORCPT ); Wed, 9 Dec 2020 14:43:20 -0500 Date: Wed, 9 Dec 2020 11:42:39 -0800 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1607542959; bh=7iFrWD0GhmOKVrp+RF5EBq1l/SLFCT+Au3bEhC/pRSI=; h=From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=UvOkcEgozn0thI74AugbRWokEZTllnGGBrbwwzK1pmmzcLCKqDaQOnYJla+yoP6Zn VgeAcUqfMrbPfD46Hpbvjs1PkH3n4QrX2mQldkwUpz4CUAa4OhFiD8+gCiyo/GmNxQ 1tglt2/y1p6r0716vWmOD9wvjkgeSK2q+8zOQMnozQT68rOdceDJd0xeeZE2BG8VxH 8XQHryZ7rKa98xzsQBFq4WraG2DoYNzvxMWB/tXsmrlBertJyaQsghZJQWrP3ncnVv o88inUcpP/LNIDk22Y7ymCYzd20aOCPApHL68iG98u2IdCQhmuC2BvFGJK4PpQitrW mvf3bhRt6TquA== From: "Paul E. McKenney" To: Uladzislau Rezki Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org, iamjoonsoo.kim@lge.com, andrii@kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2 sl-b 3/5] mm: Make mem_dump_obj() handle vmalloc() memory Message-ID: <20201209194239.GG2657@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20201209011124.GA31164@paulmck-ThinkPad-P72> <20201209011303.32737-3-paulmck@kernel.org> <20201209193637.GA5757@pc638.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201209193637.GA5757@pc638.lan> User-Agent: Mutt/1.9.4 (2018-02-28) Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org On Wed, Dec 09, 2020 at 08:36:37PM +0100, Uladzislau Rezki wrote: > On Tue, Dec 08, 2020 at 05:13:01PM -0800, paulmck@kernel.org wrote: > > From: "Paul E. McKenney" > > > > This commit adds vmalloc() support to mem_dump_obj(). Note that the > > vmalloc_dump_obj() function combines the checking and dumping, in > > contrast with the split between kmem_valid_obj() and kmem_dump_obj(). > > The reason for the difference is that the checking in the vmalloc() > > case involves acquiring a global lock, and redundant acquisitions of > > global locks should be avoided, even on not-so-fast paths. > > > > Note that this change causes on-stack variables to be reported as > > vmalloc() storage from kernel_clone() or similar, depending on the degree > > of inlining that your compiler does. This is likely more helpful than > > the earlier "non-paged (local) memory". > > > > Cc: Andrew Morton > > Cc: Joonsoo Kim > > Cc: > > Reported-by: Andrii Nakryiko > > Signed-off-by: Paul E. McKenney > > --- > > include/linux/vmalloc.h | 6 ++++++ > > mm/util.c | 12 +++++++----- > > mm/vmalloc.c | 12 ++++++++++++ > > 3 files changed, 25 insertions(+), 5 deletions(-) > > > > diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h > > index 938eaf9..c89c2be 100644 > > --- a/include/linux/vmalloc.h > > +++ b/include/linux/vmalloc.h > > @@ -248,4 +248,10 @@ pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms) > > int register_vmap_purge_notifier(struct notifier_block *nb); > > int unregister_vmap_purge_notifier(struct notifier_block *nb); > > > > +#ifdef CONFIG_MMU > > +bool vmalloc_dump_obj(void *object); > > +#else > > +static inline bool vmalloc_dump_obj(void *object) { return false; } > > +#endif > > + > > #endif /* _LINUX_VMALLOC_H */ > > diff --git a/mm/util.c b/mm/util.c > > index 8c2449f..ee99a0a 100644 > > --- a/mm/util.c > > +++ b/mm/util.c > > @@ -984,6 +984,12 @@ int __weak memcmp_pages(struct page *page1, struct page *page2) > > */ > > void mem_dump_obj(void *object) > > { > > + if (kmem_valid_obj(object)) { > > + kmem_dump_obj(object); > > + return; > > + } > > + if (vmalloc_dump_obj(object)) > > + return; > > if (!virt_addr_valid(object)) { > > if (object == NULL) > > pr_cont(" NULL pointer.\n"); > > @@ -993,10 +999,6 @@ void mem_dump_obj(void *object) > > pr_cont(" non-paged (local) memory.\n"); > > return; > > } > > - if (kmem_valid_obj(object)) { > > - kmem_dump_obj(object); > > - return; > > - } > > - pr_cont(" non-slab memory.\n"); > > + pr_cont(" non-slab/vmalloc memory.\n"); > > } > > EXPORT_SYMBOL_GPL(mem_dump_obj); > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > > index 6ae491a..7421719 100644 > > --- a/mm/vmalloc.c > > +++ b/mm/vmalloc.c > > @@ -3431,6 +3431,18 @@ void pcpu_free_vm_areas(struct vm_struct **vms, int nr_vms) > > } > > #endif /* CONFIG_SMP */ > > > > +bool vmalloc_dump_obj(void *object) > > +{ > > + struct vm_struct *vm; > > + void *objp = (void *)PAGE_ALIGN((unsigned long)object); > > > Paul, vmalloced addresses are already aligned to PAGE_SIZE, so that one > is odd. They are, but this is to handle things like this: struct foo { int a; struct rcu_head rh; }; void silly(struct foo *fp) { call_rcu(&fp->rh, my_rcu_cb); call_rcu(&fp->rh, my_other_rcu_cb); } In kernels built with CONFIG_DEBUG_OBJECTS_RCU_HEAD=y, this would result in a call to mem_dump_obj() and then to vmalloc_dump_obj() with a non-page-aligned pointer. Thanx, Paul