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 Received: from lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 329D3C5479D for ; Mon, 9 Jan 2023 21:00:14 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4NrRCw5tF1z3fLd for ; Tue, 10 Jan 2023 08:00:12 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20210112 header.b=FGVUXzbM; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=flex--surenb.bounces.google.com (client-ip=2607:f8b0:4864:20::b49; helo=mail-yb1-xb49.google.com; envelope-from=35h68ywykdpcrtqdmafnnfkd.bnlkhmtwoob-cdukhrsr.nykzar.nqf@flex--surenb.bounces.google.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20210112 header.b=FGVUXzbM; dkim-atps=neutral Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4NrR4k2Wx8z3cFt for ; Tue, 10 Jan 2023 07:53:58 +1100 (AEDT) Received: by mail-yb1-xb49.google.com with SMTP id z17-20020a25e311000000b00719e04e59e1so10330301ybd.10 for ; Mon, 09 Jan 2023 12:53:58 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=tpY24U65dxDevik5396IsQMXmVZXiLzmW2j6b7ptC2o=; b=FGVUXzbMKsAgHtVe2H+ZGPByy9vTxmIYvrPV7ZuF76ZDV4PCOupJdRY2uHLiI7i+8R 4Fjm3rnOC/ry4DX8g5MN/0YQ4aHPdCQZYFwG7UcSZ/43mvYNjuR6DmjlzCEnl8acF7KD ERVaFO4iv0zgtEZ4MmYzhpcYCiFLTkatnznfDTOltPoYyw5CvEIb1yptgTPwDbjWQDix pGxXZ1tFpWIKQUAKj6j+gMffNX2JeuA3u7s8cWrwnHHzy9T6apLvHv6bApzCw3vZvb6B a2xiK595oO97JhT8ZQYkTmP/j11qoIyiGxI24X5jHCYtpJjinnDlcXs5UPFQKhdZ/Kdz DK0A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=tpY24U65dxDevik5396IsQMXmVZXiLzmW2j6b7ptC2o=; b=Rt/5NuXQdQi/YRDOOR24Mgph85U8ZuSlFMWG0ZxuEu1gvr2BYqoBOamcRhxKThMY7c phpI7Qb8DTxLAj7x3LIIPvpziT0ruPj/iP4yKz0lTiJ6ujs7AFqxV0qCndofi22U943s unUZycWoetyjxUkEzi0fgPfffo9w3rXrJ0w0dCPFjZtLxLAjpTldYB2T0+HY+MuK+W2Y kDNWg3w33mwoOsg3FWAVdoHne4630Yf/SvULBVxIiIa1+Qarsa+A0S1SBEq0ZgigRYjq oNb4uRLI1Svx88WRnrpgyLkRD+rfJVz6BR2FXUp8z6dVi4/T9CI7f9kffUWhF53AIRVp 1pNg== X-Gm-Message-State: AFqh2koILZVve++Wfv/zycJD/wvxtj/rTLwEg7EmzHcsi9Sd/7T0eBCI ciNAATJAyfsYBZWbESL+LpEW6naxDiA= X-Google-Smtp-Source: AMrXdXs5jnkdpf0WLGjSqHJja91Z23ecX2Os+zrAvpCFIdrfHWytTqhc2UPXUEbTUa59RZZK2SYuIAkg8gM= X-Received: from surenb-desktop.mtv.corp.google.com ([2620:15c:211:200:9393:6f7a:d410:55ca]) (user=surenb job=sendgmr) by 2002:a25:2491:0:b0:7ba:cd98:5bed with SMTP id k139-20020a252491000000b007bacd985bedmr646916ybk.69.1673297636065; Mon, 09 Jan 2023 12:53:56 -0800 (PST) Date: Mon, 9 Jan 2023 12:53:01 -0800 In-Reply-To: <20230109205336.3665937-1-surenb@google.com> Mime-Version: 1.0 References: <20230109205336.3665937-1-surenb@google.com> X-Mailer: git-send-email 2.39.0.314.g84b9a713c41-goog Message-ID: <20230109205336.3665937-7-surenb@google.com> Subject: [PATCH 06/41] maple_tree: Add smp_rmb() to dead node detection From: Suren Baghdasaryan To: akpm@linux-foundation.org Content-Type: text/plain; charset="UTF-8" X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: michel@lespinasse.org, joelaf@google.com, songliubraving@fb.com, mhocko@suse.com, leewalsh@google.com, david@redhat.com, peterz@infradead.org, bigeasy@linutronix.de, peterx@redhat.com, dhowells@redhat.com, linux-mm@kvack.org, edumazet@google.com, jglisse@google.com, punit.agrawal@bytedance.com, arjunroy@google.com, dave@stgolabs.net, minchan@google.com, x86@kernel.org, hughd@google.com, willy@infradead.org, gurua@google.com, laurent.dufour@fr.ibm.com, linux-arm-kernel@lists.infradead.org, rientjes@google.com, axelrasmussen@google.com, kernel-team@android.com, soheil@google.com, paulmck@kernel.org, jannh@google.com, "Liam R. Howlett" , shakeelb@google.com, luto@kernel.org, gthelen@google.com, ldufour@linux.ibm.com, surenb@google.com, vbabka@suse.cz, posk@google.com, lstoakes@gmail.com, peterjung1337@gmail.com, linuxppc-dev@lists.ozlabs.org, kent.overstreet@linux.dev, hughlynch@google.com, linux-kernel@vger.kernel.org, hannes@cmpxchg.org, tatashin@google.co m, mgorman@techsingularity.net Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" From: "Liam R. Howlett" Add an smp_rmb() before reading the parent pointer to ensure that anything read from the node prior to the parent pointer hasn't been reordered ahead of this check. The is necessary for RCU mode. Fixes: 54a611b60590 ("Maple Tree: add new data structure") Signed-off-by: Liam R. Howlett Signed-off-by: Suren Baghdasaryan --- lib/maple_tree.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/lib/maple_tree.c b/lib/maple_tree.c index 8066fb1e8ec9..80ca28b656d3 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -535,9 +535,11 @@ static inline struct maple_node *mte_parent(const struct maple_enode *enode) */ static inline bool ma_dead_node(const struct maple_node *node) { - struct maple_node *parent = (void *)((unsigned long) - node->parent & ~MAPLE_NODE_MASK); + struct maple_node *parent; + /* Do not reorder reads from the node prior to the parent check */ + smp_rmb(); + parent = (void *)((unsigned long) node->parent & ~MAPLE_NODE_MASK); return (parent == node); } @@ -552,6 +554,8 @@ static inline bool mte_dead_node(const struct maple_enode *enode) struct maple_node *parent, *node; node = mte_to_node(enode); + /* Do not reorder reads from the node prior to the parent check */ + smp_rmb(); parent = mte_parent(enode); return (parent == node); } -- 2.39.0