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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 47673C433FE for ; Wed, 30 Nov 2022 08:34:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Type:MIME-Version: References:In-Reply-To:Message-ID:Date:Subject:CC:To:From:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=1ih/5AZ7VH4p7skGfYkFy1TDMephGSqfFTBm8ZbhGsk=; b=x2N68Jv7FE0w/wDWRZbpnuDAzU HeeOKqdcPtsBY8KwqNW5wam3/09L3F99FhG2jeNyz/MrBhlunUxEChH86VVEgDBix1TOQX7Ah0Le+ AKHsu9uIv2ng8PHZTcNWL4zA4KuMqzfEFc0OQuMmWCLRVBrivHJusJnmlrfpZdf6MtL9NgJ3xPvel 7UygOyJ0uB1tvDY9Kn9HCmPKQVJbvQv0kp2EwSB270wAfdWhv3munwRTNVgYj/4WSoKRhbewuBEKl FbShJ+eshrF8HztxjVBt95JfJq6eXeUwgqO/I/Ul6o9g5TfjjiI7HwtouP9mpC1sFHeEAvV4VaRVv 60Pb5nnw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1p0IYH-00EZtn-Fg; Wed, 30 Nov 2022 08:34:45 +0000 Received: from mailgw01.mediatek.com ([216.200.240.184]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1p0IY2-00EZhz-1z; Wed, 30 Nov 2022 08:34:31 +0000 X-UUID: 658d0a44816948968c7f727d287f55f3-20221130 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Type:MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:CC:To:From; bh=1ih/5AZ7VH4p7skGfYkFy1TDMephGSqfFTBm8ZbhGsk=; b=FcII+bSoo/NSaB5tOGDmAEsu7MGK95o6KlK8dPvz3utWjM39luFj66v5AwcXxcYbBXDUzJ4or5BA7khTg4kYXgfTcSdSCD8hq3Wu1ZNo/KtbHQ4kdUl14790zpL6nAd9B/GeZQuGKjInwYHTiLY2xQX88A5m1+BeWJ3c2POv8Yk=; X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.1.14,REQID:d9a7efeb-360b-4b99-849b-821be70a9838,IP:0,U RL:0,TC:0,Content:0,EDM:0,RT:0,SF:0,FILE:0,BULK:0,RULE:Release_Ham,ACTION: release,TS:0 X-CID-META: VersionHash:dcaaed0,CLOUDID:6794216c-41fe-47b6-8eb4-ec192dedaf7d,B ulkID:nil,BulkQuantity:0,Recheck:0,SF:102,TC:nil,Content:0,EDM:-3,IP:nil,U RL:0,File:nil,Bulk:nil,QS:nil,BEC:nil,COL:0 X-UUID: 658d0a44816948968c7f727d287f55f3-20221130 Received: from mtkmbs11n1.mediatek.inc [(172.21.101.185)] by mailgw01.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 1351694469; Wed, 30 Nov 2022 01:34:11 -0700 Received: from mtkmbs11n1.mediatek.inc (172.21.101.185) by mtkmbs10n1.mediatek.inc (172.21.101.34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.792.15; Wed, 30 Nov 2022 16:23:06 +0800 Received: from mtksdccf07.mediatek.inc (172.21.84.99) by mtkmbs11n1.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.792.15 via Frontend Transport; Wed, 30 Nov 2022 16:23:06 +0800 From: Andrew Yang To: CC: , , , , , , Subject: Re: [PATCH v2] mm/writeback: fix dereferencing NULL mapping->host Date: Wed, 30 Nov 2022 16:23:03 +0800 Message-ID: <20221130082303.30859-2-andrew.yang@mediatek.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: <20221130082303.30859-1-andrew.yang@mediatek.com> References: <20221129095620.4c1a8056@gandalf.local.home> <20221130082303.30859-1-andrew.yang@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221130_003430_143644_4AEF4D7E X-CRM114-Status: GOOD ( 17.15 ) X-BeenThere: linux-mediatek@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-mediatek" Errors-To: linux-mediatek-bounces+linux-mediatek=archiver.kernel.org@lists.infradead.org On Tue, 2022-11-29 at 09:56 -0500, Steven Rostedt wrote: > On Tue, 29 Nov 2022 11:32:59 +0800 > Andrew Yang wrote: > > > From: "andrew.yang" > > > > Check before dereferencing mapping->host > > > > Signed-off-by: andrew.yang > > --- > > include/trace/events/writeback.h | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/include/trace/events/writeback.h > > b/include/trace/events/writeback.h > > index 86b2a82da546..56f6e114d3ed 100644 > > --- a/include/trace/events/writeback.h > > +++ b/include/trace/events/writeback.h > > @@ -68,7 +68,7 @@ DECLARE_EVENT_CLASS(writeback_folio_template, > > strscpy_pad(__entry->name, > > bdi_dev_name(mapping ? > > inode_to_bdi(mapping->host) : > > NULL), 32); > > - __entry->ino = mapping ? mapping->host->i_ino : 0; > > + __entry->ino = mapping && mapping->host ? mapping- > > >host->i_ino : 0; > > I hate remembering precedence. Can we add parenthesis around this to > be > clear? > > __entry->ino = (mapping && mapping->host) ? mapping- > >host->i_ino : 0; > > Thanks, > > -- Steve > > > > __entry->index = folio->index; > > ), > > > > Sure, that's a good suggestion