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.sourceforge.net (lists.sourceforge.net [216.105.38.7]) (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 B5830C678D5 for ; Wed, 8 Mar 2023 10:33:24 +0000 (UTC) Received: from [127.0.0.1] (helo=sfs-ml-1.v29.lw.sourceforge.com) by sfs-ml-1.v29.lw.sourceforge.com with esmtp (Exim 4.95) (envelope-from ) id 1pZr6o-0008Qx-GX; Wed, 08 Mar 2023 10:33:22 +0000 Received: from [172.30.20.202] (helo=mx.sourceforge.net) by sfs-ml-1.v29.lw.sourceforge.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1pZr6k-0008QR-BO for linux-f2fs-devel@lists.sourceforge.net; Wed, 08 Mar 2023 10:33:18 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sourceforge.net; s=x; h=Content-Transfer-Encoding:Content-Type:MIME-Version :In-Reply-To:References:Message-ID:Date:Subject:CC:To:From:Sender:Reply-To: Content-ID:Content-Description:Resent-Date:Resent-From:Resent-Sender: Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help:List-Unsubscribe: List-Subscribe:List-Post:List-Owner:List-Archive; bh=6oJq2S5DkSgyuEiCBZu1W6z/4TgZv9HdLUKj/ZzNlOc=; b=LqIU2shOL+OpO/lAV0+gXiVnzq vK+tp5Z78Bb7Psb4cNd0ezDI6mVBZS9NBeZ03qfJjjtL6t4ifrKw1IbPgPL3rvuFrGBThxcaGdARs PCn0Q4herJlqup881CkAGdpZJ0Aa6bDQquV80yVq0AHGyQdh11Dm97bGZYWFPirrXY90=; DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sf.net; s=x ; h=Content-Transfer-Encoding:Content-Type:MIME-Version:In-Reply-To: References:Message-ID:Date:Subject:CC:To:From:Sender:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc :Resent-Message-ID:List-Id:List-Help:List-Unsubscribe:List-Subscribe: List-Post:List-Owner:List-Archive; bh=6oJq2S5DkSgyuEiCBZu1W6z/4TgZv9HdLUKj/ZzNlOc=; b=kpwJ0pnJbpIL1wNS7NUuM7xYyQ qUj/0r/UeShEuZYk5nt5FARGm58+motFHpPpuuYS58/ightpQq7YJZosvfpkCTECDON2ZVqxBd92K x35d1Z1F9awqagn0WuTbkGIO62wK4mMrGMABoHCecnjw1WINmqQ/QIcnEDBAF9HFxqGs=; Received: from eu-smtp-delivery-151.mimecast.com ([185.58.86.151]) by sfi-mx-1.v28.lw.sourceforge.com with esmtps (TLS1.2:ECDHE-RSA-AES256-GCM-SHA384:256) (Exim 4.95) id 1pZr6i-000c5h-BL for linux-f2fs-devel@lists.sourceforge.net; Wed, 08 Mar 2023 10:33:18 +0000 Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with both STARTTLS and AUTH (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-94-zZEPLqmLP0yTudXVspLNZQ-1; Wed, 08 Mar 2023 10:17:01 +0000 X-MC-Unique: zZEPLqmLP0yTudXVspLNZQ-1 Received: from AcuMS.Aculab.com (10.202.163.4) by AcuMS.aculab.com (10.202.163.4) with Microsoft SMTP Server (TLS) id 15.0.1497.47; Wed, 8 Mar 2023 10:16:59 +0000 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.047; Wed, 8 Mar 2023 10:16:59 +0000 From: David Laight To: 'Chao Yu' , "jaegeuk@kernel.org" Thread-Topic: [PATCH] f2fs: fix unaligned field offset in 32-bits platform Thread-Index: AQHZUQf4b45n81mohk6KYf6qmq4uP67wqZ1A Date: Wed, 8 Mar 2023 10:16:59 +0000 Message-ID: <942fe8111fdb48e583b846f3e2902228@AcuMS.aculab.com> References: <20230307151408.58490-1-chao@kernel.org> In-Reply-To: <20230307151408.58490-1-chao@kernel.org> Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US X-Headers-End: 1pZr6i-000c5h-BL Subject: Re: [f2fs-dev] [PATCH] f2fs: fix unaligned field offset in 32-bits platform X-BeenThere: linux-f2fs-devel@lists.sourceforge.net X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Zhiguo Niu , "linux-kernel@vger.kernel.org" , "linux-f2fs-devel@lists.sourceforge.net" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: linux-f2fs-devel-bounces@lists.sourceforge.net From: Chao Yu > Sent: 07 March 2023 15:14 > > F2FS-fs (dm-x): inconsistent rbtree, cur(3470333575168) next(3320009719808) > ------------[ cut here ]------------ > kernel BUG at fs/f2fs/gc.c:602! > Internal error: Oops - BUG: 0 [#1] PREEMPT SMP ARM > PC is at get_victim_by_default+0x13c0/0x1498 > LR is at f2fs_check_rb_tree_consistence+0xc4/0xd4 > .... > [] (get_victim_by_default) from [] (f2fs_gc+0x220/0x6cc) > [] (f2fs_gc) from [] (gc_thread_func+0x2ac/0x708) > [] (gc_thread_func) from [] (kthread+0x1a8/0x1b4) > [] (kthread) from [] (ret_from_fork+0x14/0x20) > > The reason is there is __packed attribute in struct rb_entry, but there > is no __packed attribute in struct victim_entry, so wrong offset of key > field will be parsed in struct rb_entry in f2fs_check_rb_tree_consistence, > it describes memory layouts of struct rb_entry and struct victim_entry in > 32-bits platform as below: > > struct rb_entry { > [0] struct rb_node rb_node; > union { > struct {...}; > [12] unsigned long long key; > } __packed; This __packed removes the 4-byte pad before the union. I bet it should be removed... > } > size of struct rb_entry: 20 > > struct victim_entry { > [0] struct rb_node rb_node; > union { > struct {...}; > [16] struct victim_info vi; > }; > [32] struct list_head list; > } > size of struct victim_entry: 40 > > This patch tries to add __packed attribute in below structure: > - discard_info, discard_cmd > - extent_info, extent_node > - victim_info, victim_entry > in order to fix this unaligned field offset issue in 32-bits platform. Have you looked at the amount of extra code that gets generated on systems that fault misaligned accesses? Plausibly adding __packed __aligned(4) will restrict the compiler to just aligning 64bit items on 32bit boundaries. But even then is you pass the address of a misaligned structure to another function it will fault later of. You haven't actually said where the misalignment comes from. If the code is doing (foo *)(ptr + 1) then that is broken when the alignments of 'ptr' and 'foo' differ. David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales) _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel