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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 36711ECAAA1 for ; Sun, 30 Oct 2022 13:37:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229743AbiJ3Nhx (ORCPT ); Sun, 30 Oct 2022 09:37:53 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52154 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229441AbiJ3Nhu (ORCPT ); Sun, 30 Oct 2022 09:37:50 -0400 Received: from sin.source.kernel.org (sin.source.kernel.org [IPv6:2604:1380:40e1:4800::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5877CC16; Sun, 30 Oct 2022 06:37:47 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id 960BCCE0BAC; Sun, 30 Oct 2022 13:37:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 565C3C433D6; Sun, 30 Oct 2022 13:37:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1667137063; bh=YuwIwrXmUckX8C/2XYw2z1oDyAYvG6egfghJlnBQBnE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ieTWRNlSUpoQLGBd94dE+h0sUtTkC+JhiaCSFmN1w78voS+cangbQAIefMzBQmp2u Om0i3pzd+Ux8l38Q5KvyHmT4DpKbEFkgM+OJPOLkuG3BBiVN6p2lXAVW6xuVMGykwJ BGvf9QNQJGrN7dqzQKg/3O1W1UJJA+JJfqfhiIF4= Date: Sun, 30 Oct 2022 14:38:39 +0100 From: Greg KH To: Oleksandr Tymoshenko Cc: christophe.leroy@csgroup.eu, davem@davemloft.net, edumazet@google.com, linux-kernel@vger.kernel.org, sashal@kernel.org, stable@vger.kernel.org, w@1wt.eu Subject: Re: [PATCH 5.4 086/255] once: add DO_ONCE_SLOW() for sleepable contexts Message-ID: References: <20221024113005.376059449@linuxfoundation.org> <20221029011211.4049810-1-ovt@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221029011211.4049810-1-ovt@google.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Oct 29, 2022 at 01:12:11AM +0000, Oleksandr Tymoshenko wrote: > Hello, > > This commit causes the following panic in kernel built with clang > (GCC build is not affected): > > [ 8.320308] BUG: unable to handle page fault for address: ffffffff97216c6a [26/4066] > [ 8.330029] #PF: supervisor write access in kernel mode > [ 8.337263] #PF: error_code(0x0003) - permissions violation > [ 8.344816] PGD 12e816067 P4D 12e816067 PUD 12e817063 PMD 800000012e2001e1 > [ 8.354337] Oops: 0003 [#1] SMP PTI > [ 8.359178] CPU: 2 PID: 437 Comm: curl Not tainted 5.4.220 #15 > [ 8.367241] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015 > [ 8.378529] RIP: 0010:__do_once_slow_done+0xf/0xa0 > [ 8.384962] Code: 1b 84 db 74 0c 48 c7 c7 80 ce 8d 97 e8 fa e9 4a 00 84 db 0f 94 c0 5b 5d c3 66 90 55 48 89 e5 41 57 41 56 > 53 49 89 d7 49 89 f6 07 01 48 c7 c7 80 ce 8d 97 e8 d2 e9 4a 00 48 8b 3d 9b de c9 00 > [ 8.409066] RSP: 0018:ffffb764c02d3c90 EFLAGS: 00010246 > [ 8.415697] RAX: 4f51d3d06bc94000 RBX: d474b86ddf7162eb RCX: 000000007229b1d6 > [ 8.424805] RDX: 0000000000000000 RSI: ffffffff9791b4a0 RDI: ffffffff97216c6a > [ 8.434108] RBP: ffffb764c02d3ca8 R08: 0e81c130f1159fc1 R09: 1d19d60ce0b52c77 > [ 8.443408] R10: 8ea59218e6892b1f R11: d5260237a3c1e35c R12: ffff9c3dadd42600 > [ 8.452468] R13: ffffffff97910f80 R14: ffffffff9791b4a0 R15: 0000000000000000 > [ 8.461416] FS: 00007eff855b40c0(0000) GS:ffff9c3db7a80000(0000) knlGS:0000000000000000 > [ 8.471632] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 8.478763] CR2: ffffffff97216c6a CR3: 000000022ded0000 CR4: 00000000000006a0 > [ 8.487789] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 8.496684] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > [ 8.505443] Call Trace: > [ 8.508568] __inet_hash_connect+0x523/0x530 > [ 8.513839] ? inet_hash_connect+0x50/0x50 > [ 8.518818] ? secure_ipv4_port_ephemeral+0x69/0xe0 > [ 8.525003] tcp_v4_connect+0x2c5/0x410 > [ 8.529858] __inet_stream_connect+0xd7/0x360 > [ 8.535329] ? _raw_spin_unlock+0xe/0x10 > ... skipped ... > > > The root cause is the difference in __section macro semantics between 5.4 and > later LTS releases. On 5.4 it stringifies the argument so the ___done > symbol is created in a bogus section ".data.once", with double quotes: > > % readelf -S vmlinux | grep data.once > [ 5] ".data.once" PROGBITS ffffffff82216c6a 01416c6a This is really odd. I just did a bunch of build tests, and this seems to only show up on the latest version of clang (14) and the 5.4 kernel. Newer kernel trees are fine, and I don't see the problem showing up on older clang releases with 5.4 (i.e. Android builds of the Android 11 release) So this is very compiler and version dependant, ugh... greg k-h