From nobody Sun Sep 22 07:48:39 2024 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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1F49CC433EF for ; Tue, 15 Mar 2022 11:31:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1347934AbiCOLce (ORCPT ); Tue, 15 Mar 2022 07:32:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59450 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1347342AbiCOLcb (ORCPT ); Tue, 15 Mar 2022 07:32:31 -0400 Received: from mailgw02.mediatek.com (unknown [210.61.82.184]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 383954DF57 for ; Tue, 15 Mar 2022 04:31:15 -0700 (PDT) X-UUID: 5540667e3a5a4bf3a40b41640f294bf4-20220315 X-UUID: 5540667e3a5a4bf3a40b41640f294bf4-20220315 Received: from mtkmbs10n1.mediatek.inc [(172.21.101.34)] by mailgw02.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 741151367; Tue, 15 Mar 2022 19:26:00 +0800 Received: from mtkcas11.mediatek.inc (172.21.101.40) by mtkmbs10n2.mediatek.inc (172.21.101.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id 15.2.792.3; Tue, 15 Mar 2022 19:25:53 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkcas11.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.0.1497.2 via Frontend Transport; Tue, 15 Mar 2022 19:25:52 +0800 From: Cheng Jui Wang To: , , CC: Peter Zijlstra , Ingo Molnar , Will Deacon , Waiman Long , Boqun Feng , Matthias Brugger , "Bart Van Assche" , , Eason-YH Lin , Kobe-CP Wu , "Jeff-cc Hsu" , Cheng Jui Wang Subject: [PATCH] lockdep: Zap lock classes with debug_locks == false again Date: Tue, 15 Mar 2022 19:25:21 +0800 Message-ID: <20220315112521.29093-1-cheng-jui.wang@mediatek.com> X-Mailer: git-send-email 2.18.0 MIME-Version: 1.0 X-MTK: N Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" If a lock_class_key has been registered but lockdep_unregister_key() is called with debug_locks =3D=3D false. The lockdep_unregister_key() will not unregister the key and just return without error. Users may assume lockdep_unregister_key() always succeed and free the lock_class_key even if it is still remained in lockdep structures. Which lead to following crash when 'cat /proc/lockdep' after debug_locks =3D=3D false: =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D BUG: KASAN: invalid-access in string+0x50/0x10c Read at addr f2ffff81ac61c880 by ... Pointer tag: [f2], memory tag: [fb] ... Call trace: dump_backtrace.cfi_jt+0x0/0x8 show_stack+0x1c/0x2c dump_stack_lvl+0xd8/0x16c print_address_description+0x90/0x2e8 __kasan_report+0x144/0x224 kasan_report+0x50/0xa0 __do_kernel_fault+0xf4/0x2a8 do_bad_area+0x34/0xf8 do_tag_check_fault+0x24/0x38 do_mem_abort+0x68/0x168 el1_abort+0x4c/0x74 el1_sync_handler+0x4c/0x8c el1_sync+0x8c/0x140 string+0x50/0x10c vsnprintf+0x468/0x69c seq_printf+0x8c/0xd8 print_name+0x64/0xf4 l_show+0x1a8/0x278 seq_read_iter+0x3cc/0x5fc proc_reg_read_iter+0xdc/0x1d4 vfs_read+0x2e0/0x354 ksys_read+0x7c/0xec __arm64_sys_read+0x20/0x30 el0_svc_common.llvm.8008154191216078041+0xd8/0x20c do_el0_svc+0x28/0xa0 el0_svc+0x24/0x38 el0_sync_handler+0x88/0xec el0_sync+0x1b4/0x1c0 ... =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D Allow lockdep_unregister_key to zap lock classes with debug_locks =3D=3D false again. Remove the WARN_ON_ONCE(!found) and only zap lock classes when the key can be found. Fixes: 8b39adbee805 ("locking/lockdep: Make lockdep_unregister_key() honor = 'debug_locks' again") Signed-off-by: Cheng Jui Wang --- kernel/locking/lockdep.c | 13 ++++++------- 1 file changed, 6 insertions(+), 7 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index f8a0212189ca..90dadecb2577 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -6305,8 +6305,7 @@ void lockdep_unregister_key(struct lock_class_key *ke= y) return; =20 raw_local_irq_save(flags); - if (!graph_lock()) - goto out_irq; + lockdep_lock(); =20 pf =3D get_pending_free(); hlist_for_each_entry_rcu(k, hash_head, hash_entry) { @@ -6316,11 +6315,11 @@ void lockdep_unregister_key(struct lock_class_key *= key) break; } } - WARN_ON_ONCE(!found); - __lockdep_free_key_range(pf, key, 1); - call_rcu_zapped(pf); - graph_unlock(); -out_irq: + if (found) { + __lockdep_free_key_range(pf, key, 1); + call_rcu_zapped(pf); + } + lockdep_unlock(); raw_local_irq_restore(flags); =20 /* Wait until is_dynamic_key() has finished accessing k->hash_entry. */ --=20 2.18.0