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=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 DF2F0C1975A for ; Tue, 17 Mar 2020 18:06:59 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 899DE20735 for ; Tue, 17 Mar 2020 18:06:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="luetIUBF" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 899DE20735 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3376F6B0005; Tue, 17 Mar 2020 14:06:59 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2E7CD6B0006; Tue, 17 Mar 2020 14:06:59 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 1FF286B0007; Tue, 17 Mar 2020 14:06:59 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0063.hostedemail.com [216.40.44.63]) by kanga.kvack.org (Postfix) with ESMTP id 08D606B0005 for ; Tue, 17 Mar 2020 14:06:59 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id CDEFF181AC9CC for ; Tue, 17 Mar 2020 18:06:58 +0000 (UTC) X-FDA: 76605635316.01.game23_3ce2e2abe9a08 X-HE-Tag: game23_3ce2e2abe9a08 X-Filterd-Recvd-Size: 7461 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf44.hostedemail.com (Postfix) with ESMTP for ; Tue, 17 Mar 2020 18:06:58 +0000 (UTC) Received: from paulmck-ThinkPad-P72.home (50-39-105-78.bvtn.or.frontiernet.net [50.39.105.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 395ED20735; Tue, 17 Mar 2020 18:06:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1584468417; bh=fhqjdz2SvIhTwHee1s+CAJH/QHf5hlfSHLnF2fRjfGU=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=luetIUBFQICDZtksurUpeGOYGQrt/b7Tf8MmcXq39WlD7ZlkDj62dp65npBxzbsr5 9MUE83I4cKdHMLctV02DyR8xL7Pyb3PIcKdHFq5OZ9RUKvPwaFruwMAyd/0hVLzh+t kDsqW9CSjvZLNCzj5a9oT9dtV73kKgJR6Hg4Cw2U= Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id 0BD0835226E2; Tue, 17 Mar 2020 11:06:57 -0700 (PDT) Date: Tue, 17 Mar 2020 11:06:57 -0700 From: "Paul E. McKenney" To: Qian Cai Cc: akpm@linux-foundation.org, jgg@ziepe.ca, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/mmu_notifier: silence PROVE_RCU_LIST warnings Message-ID: <20200317180657.GK3199@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20200317175640.2047-1-cai@lca.pw> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200317175640.2047-1-cai@lca.pw> User-Agent: Mutt/1.9.4 (2018-02-28) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Mar 17, 2020 at 01:56:40PM -0400, Qian Cai wrote: > It is safe to traverse mm->notifier_subscriptions->list either under > SRCU read lock or mm->notifier_subscriptions->lock using > hlist_for_each_entry_rcu(). Silence the PROVE_RCU_LIST false positives, > for example, > > WARNING: suspicious RCU usage > ----------------------------- > mm/mmu_notifier.c:484 RCU-list traversed in non-reader section!! > > other info that might help us debug this: > > rcu_scheduler_active = 2, debug_locks = 1 > 3 locks held by libvirtd/802: > #0: ffff9321e3f58148 (&mm->mmap_sem#2){++++}, at: do_mprotect_pkey+0xe1/0x3e0 > #1: ffffffff91ae6160 (mmu_notifier_invalidate_range_start){+.+.}, at: change_p4d_range+0x5fa/0x800 > #2: ffffffff91ae6e08 (srcu){....}, at: __mmu_notifier_invalidate_range_start+0x178/0x460 > > stack backtrace: > CPU: 7 PID: 802 Comm: libvirtd Tainted: G I 5.6.0-rc6-next-20200317+ #2 > Hardware name: HP ProLiant BL460c Gen8, BIOS I31 11/02/2014 > Call Trace: > dump_stack+0xa4/0xfe > lockdep_rcu_suspicious+0xeb/0xf5 > __mmu_notifier_invalidate_range_start+0x3ff/0x460 > change_p4d_range+0x746/0x800 > change_protection+0x1df/0x300 > mprotect_fixup+0x245/0x3e0 > do_mprotect_pkey+0x23b/0x3e0 > __x64_sys_mprotect+0x51/0x70 > do_syscall_64+0x91/0xae8 > entry_SYSCALL_64_after_hwframe+0x49/0xb3 > > Signed-off-by: Qian Cai >From an RCU perspective: Reviewed-by: Paul E. McKenney > --- > mm/mmu_notifier.c | 27 ++++++++++++++++++--------- > 1 file changed, 18 insertions(+), 9 deletions(-) > > diff --git a/mm/mmu_notifier.c b/mm/mmu_notifier.c > index ef3973a5d34a..06852b896fa6 100644 > --- a/mm/mmu_notifier.c > +++ b/mm/mmu_notifier.c > @@ -307,7 +307,8 @@ static void mn_hlist_release(struct mmu_notifier_subscriptions *subscriptions, > * ->release returns. > */ > id = srcu_read_lock(&srcu); > - hlist_for_each_entry_rcu(subscription, &subscriptions->list, hlist) > + hlist_for_each_entry_rcu(subscription, &subscriptions->list, hlist, > + srcu_read_lock_held(&srcu)) > /* > * If ->release runs before mmu_notifier_unregister it must be > * handled, as it's the only way for the driver to flush all > @@ -370,7 +371,8 @@ int __mmu_notifier_clear_flush_young(struct mm_struct *mm, > > id = srcu_read_lock(&srcu); > hlist_for_each_entry_rcu(subscription, > - &mm->notifier_subscriptions->list, hlist) { > + &mm->notifier_subscriptions->list, hlist, > + srcu_read_lock_held(&srcu)) { > if (subscription->ops->clear_flush_young) > young |= subscription->ops->clear_flush_young( > subscription, mm, start, end); > @@ -389,7 +391,8 @@ int __mmu_notifier_clear_young(struct mm_struct *mm, > > id = srcu_read_lock(&srcu); > hlist_for_each_entry_rcu(subscription, > - &mm->notifier_subscriptions->list, hlist) { > + &mm->notifier_subscriptions->list, hlist, > + srcu_read_lock_held(&srcu)) { > if (subscription->ops->clear_young) > young |= subscription->ops->clear_young(subscription, > mm, start, end); > @@ -407,7 +410,8 @@ int __mmu_notifier_test_young(struct mm_struct *mm, > > id = srcu_read_lock(&srcu); > hlist_for_each_entry_rcu(subscription, > - &mm->notifier_subscriptions->list, hlist) { > + &mm->notifier_subscriptions->list, hlist, > + srcu_read_lock_held(&srcu)) { > if (subscription->ops->test_young) { > young = subscription->ops->test_young(subscription, mm, > address); > @@ -428,7 +432,8 @@ void __mmu_notifier_change_pte(struct mm_struct *mm, unsigned long address, > > id = srcu_read_lock(&srcu); > hlist_for_each_entry_rcu(subscription, > - &mm->notifier_subscriptions->list, hlist) { > + &mm->notifier_subscriptions->list, hlist, > + srcu_read_lock_held(&srcu)) { > if (subscription->ops->change_pte) > subscription->ops->change_pte(subscription, mm, address, > pte); > @@ -476,7 +481,8 @@ static int mn_hlist_invalidate_range_start( > int id; > > id = srcu_read_lock(&srcu); > - hlist_for_each_entry_rcu(subscription, &subscriptions->list, hlist) { > + hlist_for_each_entry_rcu(subscription, &subscriptions->list, hlist, > + srcu_read_lock_held(&srcu)) { > const struct mmu_notifier_ops *ops = subscription->ops; > > if (ops->invalidate_range_start) { > @@ -528,7 +534,8 @@ mn_hlist_invalidate_end(struct mmu_notifier_subscriptions *subscriptions, > int id; > > id = srcu_read_lock(&srcu); > - hlist_for_each_entry_rcu(subscription, &subscriptions->list, hlist) { > + hlist_for_each_entry_rcu(subscription, &subscriptions->list, hlist, > + srcu_read_lock_held(&srcu)) { > /* > * Call invalidate_range here too to avoid the need for the > * subsystem of having to register an invalidate_range_end > @@ -582,7 +589,8 @@ void __mmu_notifier_invalidate_range(struct mm_struct *mm, > > id = srcu_read_lock(&srcu); > hlist_for_each_entry_rcu(subscription, > - &mm->notifier_subscriptions->list, hlist) { > + &mm->notifier_subscriptions->list, hlist, > + srcu_read_lock_held(&srcu)) { > if (subscription->ops->invalidate_range) > subscription->ops->invalidate_range(subscription, mm, > start, end); > @@ -714,7 +722,8 @@ find_get_mmu_notifier(struct mm_struct *mm, const struct mmu_notifier_ops *ops) > > spin_lock(&mm->notifier_subscriptions->lock); > hlist_for_each_entry_rcu(subscription, > - &mm->notifier_subscriptions->list, hlist) { > + &mm->notifier_subscriptions->list, hlist, > + lockdep_is_held(&mm->notifier_subscriptions->lock)) { > if (subscription->ops != ops) > continue; > > -- > 2.21.0 (Apple Git-122.2) >