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=-19.7 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_GIT 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 A874DC43462 for ; Tue, 11 May 2021 22:58:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 85BF761919 for ; Tue, 11 May 2021 22:58:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230134AbhEKW7X (ORCPT ); Tue, 11 May 2021 18:59:23 -0400 Received: from mail.kernel.org ([198.145.29.99]:38398 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229637AbhEKW7U (ORCPT ); Tue, 11 May 2021 18:59:20 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8678261606; Tue, 11 May 2021 22:58:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1620773893; bh=tjC0NkFp44jUefELqWmciYgOvqVjRwTPREzS4z26L/k=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dDnApygCdcsAvUUAkeNFO7leNVRZh64Z12a1LBxKX5xI4cDziQhuJu04hkm6CVc7P oLW6rdvJTq4X93BhQk0ji2c+7XPxUsgP9Y99xVhPRX6ReyXuLJmISlTLuJcclR2szh nkeq6eY8JKr4oVyPgOJ9K940QmjmODQBa2TuwxQ5q+GXkyOwn+7BsRfKu1m7so6iTL lXYOcwnHALFjGg8sW2lRVgztmCyXMeWgXugwZNYHpnCiN1LVFYpmusXTOvQJOAcOl9 IO5k4Xlu91OVYuAUny4H3Ug32rCSMxMOOtgs9vslxpHl2DTpnCNG5uUcPjzkwseIdV j81a6SwFBIWGg== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 58DF55C0138; Tue, 11 May 2021 15:58:13 -0700 (PDT) From: "Paul E. McKenney" To: rcu@vger.kernel.org Cc: 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, Maninder Singh , Vlastimil Babka , Vaneet Narang , "Paul E . McKenney" Subject: [PATCH tip/core/rcu 1/2] mm/slub: Fix backtrace of objects to handle redzone adjustment Date: Tue, 11 May 2021 15:58:10 -0700 Message-Id: <20210511225811.2893697-1-paulmck@kernel.org> X-Mailer: git-send-email 2.31.1.189.g2e36527f23 In-Reply-To: <20210511225744.GA2893615@paulmck-ThinkPad-P17-Gen-1> References: <20210511225744.GA2893615@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Maninder Singh This commit fixes commit 8e7f37f2aaa5 ("mm: Add mem_dump_obj() to print source of memory block"). With current code, the backtrace of allocated object is incorrect: / # cat /proc/meminfo [ 14.969843] slab kmalloc-64 start c8ab0140 data offset 64 pointer offset 0 size 64 allocated at 0x6b6b6b6b [ 14.970635] 0x6b6b6b6b [ 14.970794] 0x6b6b6b6b [ 14.970932] 0x6b6b6b6b [ 14.971077] 0x6b6b6b6b [ 14.971202] 0x6b6b6b6b [ 14.971317] 0x6b6b6b6b [ 14.971423] 0x6b6b6b6b [ 14.971635] 0x6b6b6b6b [ 14.971740] 0x6b6b6b6b [ 14.971871] 0x6b6b6b6b [ 14.972229] 0x6b6b6b6b [ 14.972363] 0x6b6b6b6b [ 14.972505] 0xa56b6b6b [ 14.972631] 0xbbbbbbbb [ 14.972734] 0xc8ab0400 [ 14.972891] meminfo_proc_show+0x40/0x4fc The reason is that the object address was not adjusted for the red zone. With this fix, the backtrace is correct: / # cat /proc/meminfo [ 14.870782] slab kmalloc-64 start c8ab0140 data offset 64 pointer offset 128 size 64 allocated at meminfo_proc_show+0x40/0x4f4 [ 14.871817] meminfo_proc_show+0x40/0x4f4 [ 14.872035] seq_read_iter+0x18c/0x4c4 [ 14.872229] proc_reg_read_iter+0x84/0xac [ 14.872433] generic_file_splice_read+0xe8/0x17c [ 14.872621] splice_direct_to_actor+0xb8/0x290 [ 14.872747] do_splice_direct+0xa0/0xe0 [ 14.872896] do_sendfile+0x2d0/0x438 [ 14.873044] sys_sendfile64+0x12c/0x140 [ 14.873229] ret_fast_syscall+0x0/0x58 [ 14.873372] 0xbe861de4 Acked-by: Vlastimil Babka Signed-off-by: Vaneet Narang Signed-off-by: Maninder Singh Signed-off-by: Paul E. McKenney --- mm/slub.c | 1 + 1 file changed, 1 insertion(+) diff --git a/mm/slub.c b/mm/slub.c index feda53ae62ba..8f2d13508ec9 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -4002,6 +4002,7 @@ void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct page *page) !(s->flags & SLAB_STORE_USER)) return; #ifdef CONFIG_SLUB_DEBUG + objp = fixup_red_left(s, objp); trackp = get_track(s, objp, TRACK_ALLOC); kpp->kp_ret = (void *)trackp->addr; #ifdef CONFIG_STACKTRACE -- 2.31.1.189.g2e36527f23