Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934268AbcKNQ5d (ORCPT ); Mon, 14 Nov 2016 11:57:33 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:57589 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932515AbcKNQ5W (ORCPT ); Mon, 14 Nov 2016 11:57:22 -0500 From: "Paul E. McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.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, dvhart@linux.intel.com, fweisbec@gmail.com, oleg@redhat.com, bobby.prani@gmail.com, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 1/7] rcu: Tighten up __call_rcu() rcu_head alignment check Date: Mon, 14 Nov 2016 08:57:07 -0800 X-Mailer: git-send-email 2.5.2 In-Reply-To: <20161114165648.GA15216@linux.vnet.ibm.com> References: <20161114165648.GA15216@linux.vnet.ibm.com> X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16111416-0008-0000-0000-000006133D94 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00006077; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000189; SDB=6.00780603; UDB=6.00376436; IPR=6.00558103; BA=6.00004878; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00013321; XFM=3.00000011; UTC=2016-11-14 16:57:19 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16111416-0009-0000-0000-00003D005153 Message-Id: <1479142633-15315-1-git-send-email-paulmck@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-11-14_10:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1609300000 definitions=main-1611140342 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1218 Lines: 31 Commit 720abae3d68ae ("rcu: force alignment on struct callback_head/rcu_head") forced the rcu_head (AKA callback_head) structure's alignment to pointer size, that is, to 4-byte boundaries on 32-bit systems and to 8-byte boundaries on 64-bit systems. This commit therefore checks for this same alignment in __call_rcu(), which used to contain a looser check for two-byte alignment. Signed-off-by: Paul E. McKenney Tested-by: Geert Uytterhoeven Acked-by: Kirill A. Shutemov --- kernel/rcu/tree.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 69a5611a7e7c..37e4f7d2be0c 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3121,7 +3121,9 @@ __call_rcu(struct rcu_head *head, rcu_callback_t func, unsigned long flags; struct rcu_data *rdp; - WARN_ON_ONCE((unsigned long)head & 0x1); /* Misaligned rcu_head! */ + /* Misaligned rcu_head! */ + WARN_ON_ONCE((unsigned long)head & (sizeof(void *) - 1)); + if (debug_rcu_head_queue(head)) { /* Probable double call_rcu(), so leak the callback. */ WRITE_ONCE(head->func, rcu_leak_callback); -- 2.5.2