From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1524723207; cv=none; d=google.com; s=arc-20160816; b=bq8KO/eHt1TifS1yzqM3o5U+d70BtKto0mzokhFaHGwnJdd1MUgUA+uom29HCqf14u gAe08hhtNSK0yuR7DEVhBMaCV4STMyww6Lnz6/CpQ7DEkGNCUfmVYe8WiU3uATaRlPxF p6RBXYjdWAeOrQHOkwux6Xs95kEsKUk8u3k/72hrqjfS34O5c8DuLoWY0ufmVaneCcE5 JZLzqbvrX2Qy+haF6CTxvnugmIVyvPbJQQlIZUtK2axKfJur0kbVJp0CpWDO9kGCNCdv 7M61FfRem0AgxLprv4lEXhPzH8g1gBYILlmdOC1rGl+9ni91bVbyoZMyLTRhMV4B/MCC 4CtA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=user-agent:in-reply-to:content-disposition:mime-version:references :message-id:subject:cc:to:from:date:dkim-signature :arc-authentication-results; bh=MqKO5F9VvU/AtEuGEAuq1oM08xksqAUkA+HK8iGJ33A=; b=NopGPGA/WsgsPMFIg/dO1tktHfE254aPxVRaPKMNmX6txATDfgCsQouS5BErG95UVP xWjgA0ffEdTBRAXpabY5yah2wDFw8E82Lj1ZNxU2F2UlG2iZEB6X1Vzd+HAX31xReifb HCRjwgqRmiLvG8RMPRVgeZ20o1x4ymISKJ7qKg7gB3aAdgykrBKL/gLAvKoIISavnIx8 o2DsYPy3gmbWoxh6AggW3yodbYyJYxN7weYOIQDplZYlv3ZOPV3mvKorp3X9bVXTxlEB bTkxVEOq6vxi3VrwMIVfU4dJQ2ieWt87WKqNnagwvL9kfunsoD7RrFlFY+KQhEWIzxZT jkKg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=BeseXGhB; spf=pass (google.com: domain of liuhangbin@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=liuhangbin@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=BeseXGhB; spf=pass (google.com: domain of liuhangbin@gmail.com designates 209.85.220.41 as permitted sender) smtp.mailfrom=liuhangbin@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com X-Google-Smtp-Source: AB8JxZrtBuKNmqMeocIKJEZxM2SSlqvpV+C9wb+5byyJdLqfUloM2/AQ4VDSeHTMod+bndNsVD9nog== Date: Thu, 26 Apr 2018 14:13:15 +0800 From: Hangbin Liu To: Dmitry Vyukov Cc: syzbot , bridge@lists.linux-foundation.org, David Miller , LKML , netdev , stephen hemminger , syzkaller-bugs , Greg Kroah-Hartman Subject: Re: WARNING: kobject bug in br_add_if Message-ID: <20180426061314.GH20683@leo.usersys.redhat.com> References: <001a113de2d878ade40569941a21@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.7.0 (2016-08-17) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcSW1wb3J0YW50Ig==?= X-GMAIL-THRID: =?utf-8?q?1597463513858460385?= X-GMAIL-MSGID: =?utf-8?q?1598788162098473700?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Wed, Apr 11, 2018 at 05:18:23PM +0200, Dmitry Vyukov wrote: > On Wed, Apr 11, 2018 at 5:15 PM, syzbot > wrote: > > Hello, > > > > syzbot hit the following crash on upstream commit > > 10b84daddbec72c6b440216a69de9a9605127f7a (Sat Mar 31 17:59:00 2018 +0000) > > Merge branch 'perf-urgent-for-linus' of > > git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip > > syzbot dashboard link: > > https://syzkaller.appspot.com/bug?extid=de73361ee4971b6e6f75 > > > > So far this crash happened 4 times on net-next, upstream. > > Unfortunately, I don't have any reproducer for this crash yet. > > Raw console output: > > https://syzkaller.appspot.com/x/log.txt?id=5007286875455488 > > Kernel config: > > https://syzkaller.appspot.com/x/.config?id=-2760467897697295172 > > compiler: gcc (GCC) 7.1.1 20170620 > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > Reported-by: syzbot+de73361ee4971b6e6f75@syzkaller.appspotmail.com > > It will help syzbot understand when the bug is fixed. See footer for > > details. > > If you forward the report, please keep this part and the footer. > > +Greg > > The plan is to remove this WARNING from kobject_add, if there are no objections. Hi Dmitry, For this bug, why should we remove the WARNING instead of adding a check in br_add_if()? Something like diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c index 82c1a6f..79dcc3d 100644 --- a/net/bridge/br_if.c +++ b/net/bridge/br_if.c @@ -518,8 +518,8 @@ int br_add_if(struct net_bridge *br, struct net_device *dev, return -ELOOP; } - /* Device is already being bridged */ - if (br_port_exists(dev)) + /* Device still has master upper dev */ + if (netdev_master_upper_dev_get(dev)) return -EBUSY; /* No bridging devices that dislike that (e.g. wireless) */ Thanks Hangbin > > > ------------[ cut here ]------------ > > binder: 23650:23651 unknown command 1078223622 > > kobject_add_internal failed for brport (error: -12 parent: bond0) > > binder: 23650:23651 ioctl c0306201 2000dfd0 returned -22 > > WARNING: CPU: 1 PID: 23647 at lib/kobject.c:242 > > kobject_add_internal+0x3f6/0xbc0 lib/kobject.c:240 > > Kernel panic - not syncing: panic_on_warn set ... > > > > CPU: 1 PID: 23647 Comm: syz-executor7 Not tainted 4.16.0-rc7+ #374 > > binder: BINDER_SET_CONTEXT_MGR already set > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > > Google 01/01/2011 > > Call Trace: > > __dump_stack lib/dump_stack.c:17 [inline] > > dump_stack+0x194/0x24d lib/dump_stack.c:53 > > panic+0x1e4/0x41c kernel/panic.c:183 > > __warn+0x1dc/0x200 kernel/panic.c:547 > > report_bug+0x1f4/0x2b0 lib/bug.c:186 > > fixup_bug.part.10+0x37/0x80 arch/x86/kernel/traps.c:178 > > fixup_bug arch/x86/kernel/traps.c:247 [inline] > > do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296 > > do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315 > > invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:986 > > RIP: 0010:kobject_add_internal+0x3f6/0xbc0 lib/kobject.c:240 > > RSP: 0018:ffff8801d089f560 EFLAGS: 00010286 > > RAX: dffffc0000000008 RBX: ffff8801adbee178 RCX: ffffffff815b193e > > RDX: 0000000000040000 RSI: ffffc900022aa000 RDI: 1ffff1003a113e31 > > RBP: ffff8801d089f658 R08: 1ffff1003a113df3 R09: 0000000000000000 > > R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff1003a113eb2 > > R13: 00000000fffffff4 R14: ffff8801abd88828 R15: ffff8801d75a1e00 > > kobject_add_varg lib/kobject.c:364 [inline] > > kobject_init_and_add+0xf9/0x150 lib/kobject.c:436 > > br_add_if+0x79a/0x1a70 net/bridge/br_if.c:533 > > add_del_if+0xf4/0x140 net/bridge/br_ioctl.c:101 > > br_dev_ioctl+0xa2/0xc0 net/bridge/br_ioctl.c:396 > > dev_ifsioc+0x333/0x9b0 net/core/dev_ioctl.c:334 > > dev_ioctl+0x176/0xbe0 net/core/dev_ioctl.c:500 > > sock_do_ioctl+0x1ba/0x390 net/socket.c:981 > > sock_ioctl+0x367/0x670 net/socket.c:1081 > > vfs_ioctl fs/ioctl.c:46 [inline] > > do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 > > SYSC_ioctl fs/ioctl.c:701 [inline] > > SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 > > do_syscall_64+0x281/0x940 arch/x86/entry/common.c:287 > > entry_SYSCALL_64_after_hwframe+0x42/0xb7 > > RIP: 0033:0x454e79 > > RSP: 002b:00007eff7dab7c68 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > > RAX: ffffffffffffffda RBX: 00007eff7dab86d4 RCX: 0000000000454e79 > > RDX: 0000000020000000 RSI: 00000000000089a2 RDI: 0000000000000014 > > RBP: 000000000072bea0 R08: 0000000000000000 R09: 0000000000000000 > > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000015 > > R13: 0000000000000369 R14: 00000000006f7278 R15: 0000000000000006 > > Dumping ftrace buffer: > > (ftrace buffer empty) > > Kernel Offset: disabled > > Rebooting in 86400 seconds..