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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 61B68CAC5A5 for ; Wed, 24 Sep 2025 02:20:11 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 6636C8E0006; Tue, 23 Sep 2025 22:20:10 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 63B848E0001; Tue, 23 Sep 2025 22:20:10 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 578C78E0006; Tue, 23 Sep 2025 22:20:10 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 47B348E0001 for ; Tue, 23 Sep 2025 22:20:10 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id DB6E4C0397 for ; Wed, 24 Sep 2025 02:20:09 +0000 (UTC) X-FDA: 83922538938.20.6EC6904 Received: from out-184.mta0.migadu.com (out-184.mta0.migadu.com [91.218.175.184]) by imf07.hostedemail.com (Postfix) with ESMTP id 264EE40005 for ; Wed, 24 Sep 2025 02:20:05 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=S+P74MdS; spf=pass (imf07.hostedemail.com: domain of chengming.zhou@linux.dev designates 91.218.175.184 as permitted sender) smtp.mailfrom=chengming.zhou@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1758680408; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=MtYamX9PaOFosODiXhH4M2cLp1DMRUmAKSkQRg2/kMc=; b=76bKB6fhhwlGHTTn8ypmq6khjN7z/V57hHwDNCSqJVKDL5vB6OwZXrvjVAECmPfp4G+3bj ICZ5M0pSMC9BQr6QXFsZ7VYEY21BtsmByn5+47gSUr+uXNZj4cKDkHPVm5T+f4gzuHYP4B hNV629K8kY7SuqPHyrC49JD4lPOK87c= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1758680408; a=rsa-sha256; cv=none; b=gcWlmAurcPAwVWhMCfRoAv3FN9l9OA+2moSthvgvjRZ+ToFsUslV/OMpBjx8+B5ebKL9T0 54L9eo2Q5mdHD4vqJt/5GZFdPV5sOAWtDLVmqpKsTAfqlukSheBLZXXkWLneiPOM+2QINi 3JKTHAykLriX68VmTvZ6VuBUuEEd+tU= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=S+P74MdS; spf=pass (imf07.hostedemail.com: domain of chengming.zhou@linux.dev designates 91.218.175.184 as permitted sender) smtp.mailfrom=chengming.zhou@linux.dev; dmarc=pass (policy=none) header.from=linux.dev Message-ID: <99731e65-9092-48c2-ae65-bb8d6247664f@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1758680403; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=MtYamX9PaOFosODiXhH4M2cLp1DMRUmAKSkQRg2/kMc=; b=S+P74MdSSb9L710oxw0CKA8sKcBY7sIMA3tqnfXdaJS4tiVRc2H+nFTq5mO5VkKu1CZ3b4 yR4mwyvzvYzuq2Ya2oyae1tgTU4uo3OYFyY0mEzsnABvleRlPWCcrUsiFGDg75ZUn0SRME s6iFttbv5sPrQ5h+XEqjuk0UX7ZeSSM= Date: Wed, 24 Sep 2025 10:19:53 +0800 MIME-Version: 1.0 Subject: Re: [Patch v3 1/2] mm/ksm: get mm_slot by mm_slot_entry() when slot is !NULL To: Wei Yang , akpm@linux-foundation.org, david@redhat.com, lorenzo.stoakes@oracle.com, ziy@nvidia.com, baolin.wang@linux.alibaba.com, Liam.Howlett@oracle.com, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, xu.xin16@zte.com.cn Cc: linux-mm@kvack.org, Kiryl Shutsemau , Dan Carpenter References: <20250924004854.29889-1-richard.weiyang@gmail.com> <20250924004854.29889-2-richard.weiyang@gmail.com> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Chengming Zhou In-Reply-To: <20250924004854.29889-2-richard.weiyang@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Stat-Signature: 5awtq1mooikepa9bpd9qqdgfo9cfzqo3 X-Rspamd-Queue-Id: 264EE40005 X-Rspam-User: X-Rspamd-Server: rspam03 X-HE-Tag: 1758680405-508005 X-HE-Meta: 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 D25bCsup VQXfVGOnnQwY5wxI2N2W/fzOnnDyhl4p4n64xe3uSOO5DqJTlcgFSR0eJ7qgGLkFHQu7jgWGdVFzdf5pOXV5b27fxAzT1TH5IHPh64sZrOhsebA+J01NrqK2WtEQYFT40lpJPmwX41qY4hFzJTtLZHuJiQ5Ms0FRmDWhFZq5Mo14jE8aYPaSxuQeZFKWQgzZDlCZKeNpGc8+oWHeYW/Qm2XhzJnZn3pyKDJV3eVCrBlj5SDrwjJRG3jMFMAFUzvm3xYyBYUrZLvZQW7hwV72ENCjvAccrkspUd78/jTNPtSJgsFyv4FP1KhXhnxkFummHuf5xadIC5akn+YvJmf48h3d67Hyb1M/V1QuYbSftue70Dv6SFKUiLuIHkQ3nfP9x3TA93wkZkoH/ZhkTMtmgO7j3CfVTWKQvtqwSaBCTcxGz0Pn8w3Gm4O69BSmD36Shvyi5QD+fORh0TyJ9PK9pjwM4iiHsRnXdSt1Y0Xa5x8/KpVnVifXC6JQ9iPK1yyuxofPve8nvq+6HJZMJOFy9VDxgLwi/wSZES3hquGeao+V/QSKFc3RjtNMDIr5lGL5vZSQ+oUU7LgLRevF8Gp+KFdU8SKlwaI7PFpy9UW++8zEd3vfno13uMg44ZQ== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2025/9/24 08:48, Wei Yang wrote: > Patch series "mm_slot: fix the usage of mm_slot_entry", v2. > > When using mm_slot in ksm, there is code like: > > slot = mm_slot_lookup(mm_slots_hash, mm); > mm_slot = mm_slot_entry(slot, struct ksm_mm_slot, slot); > if (mm_slot && ..) { > } > > The mm_slot_entry() won't return a valid value if slot is NULL generally. > But currently it works since slot is the first element of struct > ksm_mm_slot. > > To reduce the ambiguity and make it robust, access mm_slot_entry() when > slot is !NULL. > > Signed-off-by: Wei Yang > Acked-by: David Hildenbrand > Reviewed-by: Dev Jain > Reviewed-by: Lance Yang > Cc: Kiryl Shutsemau > Cc: xu xin > Cc: Dan Carpenter Reviewed-by: Chengming Zhou Thanks. > > --- > v3: > * fix uninitialized mm_slot > --- > mm/ksm.c | 22 ++++++++++++---------- > 1 file changed, 12 insertions(+), 10 deletions(-) > > diff --git a/mm/ksm.c b/mm/ksm.c > index 2dbe92e3dd52..c00a21800067 100644 > --- a/mm/ksm.c > +++ b/mm/ksm.c > @@ -2921,7 +2921,7 @@ int __ksm_enter(struct mm_struct *mm) > > void __ksm_exit(struct mm_struct *mm) > { > - struct ksm_mm_slot *mm_slot; > + struct ksm_mm_slot *mm_slot = NULL; > struct mm_slot *slot; > int easy_to_free = 0; > > @@ -2936,15 +2936,17 @@ void __ksm_exit(struct mm_struct *mm) > > spin_lock(&ksm_mmlist_lock); > slot = mm_slot_lookup(mm_slots_hash, mm); > - mm_slot = mm_slot_entry(slot, struct ksm_mm_slot, slot); > - if (mm_slot && ksm_scan.mm_slot != mm_slot) { > - if (!mm_slot->rmap_list) { > - hash_del(&slot->hash); > - list_del(&slot->mm_node); > - easy_to_free = 1; > - } else { > - list_move(&slot->mm_node, > - &ksm_scan.mm_slot->slot.mm_node); > + if (slot) { > + mm_slot = mm_slot_entry(slot, struct ksm_mm_slot, slot); > + if (ksm_scan.mm_slot != mm_slot) { > + if (!mm_slot->rmap_list) { > + hash_del(&slot->hash); > + list_del(&slot->mm_node); > + easy_to_free = 1; > + } else { > + list_move(&slot->mm_node, > + &ksm_scan.mm_slot->slot.mm_node); > + } > } > } > spin_unlock(&ksm_mmlist_lock);