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Darwish" , Eric Dumazet CC: "David S . Miller" , Jakub Kicinski , netdev , Eric Dumazet , Sebastian Andrzej Siewior Subject: Re: [PATCH net-next 1/2] net: sched: fix logic error in qdisc_run_begin() In-Reply-To: <20211019003402.2110017-2-eric.dumazet@gmail.com> Date: Wed, 20 Oct 2021 10:32:53 +0300 Message-ID: MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [172.20.187.6] X-ClientProxiedBy: HQMAIL107.nvidia.com (172.20.187.13) To HQMAIL107.nvidia.com (172.20.187.13) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: d14e6bea-9f63-4323-c848-08d9939bda0a X-MS-TrafficTypeDiagnostic: BY5PR12MB4801: X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:2512; X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:216.228.112.34;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:schybrid03.nvidia.com;CAT:NONE;SFS:(4636009)(46966006)(36840700001)(70586007)(70206006)(7636003)(336012)(82310400003)(356005)(426003)(8936002)(2906002)(5660300002)(2616005)(83380400001)(4326008)(36756003)(54906003)(186003)(16526019)(45080400002)(26005)(6666004)(110136005)(8676002)(508600001)(316002)(47076005)(86362001)(7696005)(36860700001);DIR:OUT;SFP:1101; X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 20 Oct 2021 07:33:03.5920 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: d14e6bea-9f63-4323-c848-08d9939bda0a X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.112.34];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: DM6NAM11FT030.eop-nam11.prod.protection.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: BY5PR12MB4801 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue 19 Oct 2021 at 03:34, Eric Dumazet wrote: > From: Eric Dumazet > > For non TCQ_F_NOLOCK qdisc, qdisc_run_begin() tries to set > __QDISC_STATE_RUNNING and should return true if the bit was not set. > > test_and_set_bit() returns old bit value, therefore we need to invert. > > Fixes: 29cbcd858283 ("net: sched: Remove Qdisc::running sequence counter") > Signed-off-by: Eric Dumazet > Cc: Ahmed S. Darwish > Cc: Sebastian Andrzej Siewior > --- We've got a warning[0] in today's regression that was added by commit that this patch fixes. I can't reproduce it manually and from changelog it is hard to determine whether the fix is for the issue we experiencing or something else. WDYT? [0]: [Wed Oct 20 09:08:06 2021] ------------[ cut here ]------------ [Wed Oct 20 09:08:06 2021] WARNING: CPU: 4 PID: 0 at net/core/gen_stats.c:157 gnet_stats_add_basic+0x1d9/0x240 [Wed Oct 20 09:08:06 2021] Modules linked in: act_vlan cls_flower act_tunnel_key sch_ingress openvswitch nsh mlx5_ib mlx5_core xt_conntrack xt_MASQUERADE nf_conntrack_netlink nfnetlink rpcrdma rdma_ucm ib_iser libiscsi scsi_transport_iscsi rdma_cm ib_umad iw_cm ib_ipoib ib_cm xt_addrtype iptable_nat nf_nat br_netfilter ib_uverbs ib_core overlay fuse [last unloaded: mlx5_core] [Wed Oct 20 09:08:06 2021] CPU: 4 PID: 0 Comm: swapper/4 Not tainted 5.15.0-rc6_for_upstream_debug_2021_10_19_17_13 #1 [Wed Oct 20 09:08:06 2021] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 [Wed Oct 20 09:08:06 2021] RIP: 0010:gnet_stats_add_basic+0x1d9/0x240 [Wed Oct 20 09:08:06 2021] Code: 25 a0 19 1e 02 0f 82 4a ff ff ff 48 8b 44 24 20 4c 01 28 44 8b 24 24 4c 01 60 08 48 83 c4 28 5b 5d 41 5c 41 5d 41 5e 41 5f c3 <0f> 0b e9 d1 fe ff ff 48 89 df e8 d8 4c 07 ff e9 62 fe ff ff 48 89 [Wed Oct 20 09:08:06 2021] RSP: 0018:ffff8882a4209b80 EFLAGS: 00010206 [Wed Oct 20 09:08:06 2021] RAX: 0000000080000102 RBX: ffff888116bda450 RCX: 0000000000000000 [Wed Oct 20 09:08:06 2021] RDX: ffff888116bda450 RSI: 0000607d5b844340 RDI: ffff8882a4209c90 [Wed Oct 20 09:08:06 2021] RBP: 0000607d5b844340 R08: 0000000000000001 R09: 0000000000000003 [Wed Oct 20 09:08:06 2021] R10: ffffed105484136e R11: 0000000000000001 R12: ffff888122b10608 [Wed Oct 20 09:08:06 2021] R13: ffff888122b10680 R14: ffff888122b10680 R15: ffff888122b10621 [Wed Oct 20 09:08:06 2021] FS: 0000000000000000(0000) GS:ffff8882a4200000(0000) knlGS:0000000000000000 [Wed Oct 20 09:08:06 2021] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [Wed Oct 20 09:08:06 2021] CR2: 0000561dba20e5b8 CR3: 0000000004026003 CR4: 0000000000370ea0 [Wed Oct 20 09:08:06 2021] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [Wed Oct 20 09:08:06 2021] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [Wed Oct 20 09:08:06 2021] Call Trace: [Wed Oct 20 09:08:06 2021] [Wed Oct 20 09:08:06 2021] ? rcu_core+0x642/0x1fd0 [Wed Oct 20 09:08:06 2021] est_fetch_counters+0xc8/0x150 [Wed Oct 20 09:08:06 2021] ? __do_softirq+0x282/0x94e [Wed Oct 20 09:08:06 2021] ? __irq_exit_rcu+0x11f/0x170 [Wed Oct 20 09:08:06 2021] est_timer+0x95/0x6f0 [Wed Oct 20 09:08:06 2021] ? rcu_read_lock_sched_held+0x12/0x70 [Wed Oct 20 09:08:06 2021] ? lock_acquire+0x38d/0x4c0 [Wed Oct 20 09:08:06 2021] ? rcu_read_lock_sched_held+0x12/0x70 [Wed Oct 20 09:08:06 2021] ? lockdep_hardirqs_on_prepare+0x400/0x400 [Wed Oct 20 09:08:06 2021] ? est_fetch_counters+0x150/0x150 [Wed Oct 20 09:08:06 2021] ? lock_release+0x460/0x750 [Wed Oct 20 09:08:06 2021] ? scheduler_tick+0x290/0x860 [Wed Oct 20 09:08:06 2021] ? est_fetch_counters+0x150/0x150 [Wed Oct 20 09:08:06 2021] ? call_timer_fn+0x178/0x490 [Wed Oct 20 09:08:06 2021] call_timer_fn+0x178/0x490 [Wed Oct 20 09:08:06 2021] ? lock_release+0x460/0x750 [Wed Oct 20 09:08:06 2021] ? msleep_interruptible+0x130/0x130 [Wed Oct 20 09:08:07 2021] ? lock_downgrade+0x6e0/0x6e0 [Wed Oct 20 09:08:07 2021] ? __next_timer_interrupt+0xfc/0x200 [Wed Oct 20 09:08:07 2021] ? est_fetch_counters+0x150/0x150 [Wed Oct 20 09:08:07 2021] __run_timers.part.0+0x545/0x890 [Wed Oct 20 09:08:07 2021] ? call_timer_fn+0x490/0x490 [Wed Oct 20 09:08:07 2021] ? lock_downgrade+0x6e0/0x6e0 [Wed Oct 20 09:08:07 2021] ? kvm_clock_get_cycles+0x14/0x20 [Wed Oct 20 09:08:07 2021] ? ktime_get+0xb3/0x180 [Wed Oct 20 09:08:07 2021] ? lapic_next_deadline+0x3c/0x90 [Wed Oct 20 09:08:07 2021] ? clockevents_program_event+0x1dc/0x2f0 [Wed Oct 20 09:08:07 2021] run_timer_softirq+0x6a/0x100 [Wed Oct 20 09:08:07 2021] __do_softirq+0x282/0x94e [Wed Oct 20 09:08:07 2021] __irq_exit_rcu+0x11f/0x170 [Wed Oct 20 09:08:07 2021] irq_exit_rcu+0xa/0x20 [Wed Oct 20 09:08:07 2021] sysvec_apic_timer_interrupt+0x6f/0x90 [Wed Oct 20 09:08:07 2021] [Wed Oct 20 09:08:07 2021] asm_sysvec_apic_timer_interrupt+0x12/0x20 [Wed Oct 20 09:08:07 2021] RIP: 0010:default_idle+0x53/0x70 [Wed Oct 20 09:08:07 2021] Code: c1 83 e0 07 48 c1 e9 03 83 c0 03 0f b6 14 11 38 d0 7c 04 84 d2 75 14 8b 05 3a 9f f4 01 85 c0 7e 07 0f 00 2d 6f a7 4c 00 fb f4 48 c7 c7 a0 d5 2c 85 e8 c0 52 57 fe eb de 66 66 2e 0f 1f 84 00 [Wed Oct 20 09:08:07 2021] RSP: 0018:ffff888100c57df8 EFLAGS: 00000246 [Wed Oct 20 09:08:07 2021] RAX: 0000000000000000 RBX: ffff888100c42000 RCX: 1ffffffff0a59ab4 [Wed Oct 20 09:08:07 2021] RDX: 0000000000000004 RSI: 0000000000000004 RDI: ffffffff852cd5a0 [Wed Oct 20 09:08:07 2021] RBP: 0000000000000004 R08: 0000000000000000 R09: 0000000000000003 [Wed Oct 20 09:08:07 2021] R10: fffffbfff0a59ab4 R11: 0000000000000001 R12: ffffed1020188400 [Wed Oct 20 09:08:07 2021] R13: ffffffff84a65440 R14: 0000000000000000 R15: dffffc0000000000 [Wed Oct 20 09:08:07 2021] ? default_idle+0x16/0x70 [Wed Oct 20 09:08:07 2021] default_idle_call+0x8c/0xd0 [Wed Oct 20 09:08:07 2021] do_idle+0x394/0x450 [Wed Oct 20 09:08:07 2021] ? arch_cpu_idle_exit+0x40/0x40 [Wed Oct 20 09:08:07 2021] cpu_startup_entry+0x19/0x20 [Wed Oct 20 09:08:07 2021] start_secondary+0x229/0x2f0 [Wed Oct 20 09:08:07 2021] ? set_cpu_sibling_map+0x1830/0x1830 [Wed Oct 20 09:08:07 2021] secondary_startup_64_no_verify+0xb0/0xbb [Wed Oct 20 09:08:07 2021] irq event stamp: 4163175 [Wed Oct 20 09:08:07 2021] hardirqs last enabled at (4163175): [] default_idle_call+0x54/0xd0 [Wed Oct 20 09:08:07 2021] hardirqs last disabled at (4163174): [] do_idle+0x126/0x450 [Wed Oct 20 09:08:07 2021] softirqs last enabled at (4163146): [] __irq_exit_rcu+0x11f/0x170 [Wed Oct 20 09:08:07 2021] softirqs last disabled at (4163141): [] __irq_exit_rcu+0x11f/0x170 [Wed Oct 20 09:08:07 2021] ---[ end trace 522aedc0980d5e9b ]--- > include/net/sch_generic.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h > index baad2ab4d971cd3fdc8d59acdd72d39fa6230370..e0988c56dd8fd7aa3dff6bd971da3c81f1a20626 100644 > --- a/include/net/sch_generic.h > +++ b/include/net/sch_generic.h > @@ -217,7 +217,7 @@ static inline bool qdisc_run_begin(struct Qdisc *qdisc) > */ > return spin_trylock(&qdisc->seqlock); > } > - return test_and_set_bit(__QDISC_STATE_RUNNING, &qdisc->state); > + return !test_and_set_bit(__QDISC_STATE_RUNNING, &qdisc->state); > } > > static inline void qdisc_run_end(struct Qdisc *qdisc)