On Wed, Nov 30, 2016 at 5:58 PM, Eric Dumazet <eric.duma...@gmail.com> wrote: > On Wed, 2016-11-30 at 15:08 +0100, Jesper Dangaard Brouer wrote: >> On Fri, 25 Nov 2016 07:46:20 -0800 Eric Dumazet <eric.duma...@gmail.com> >> wrote: >> >> > From: Eric Dumazet <eduma...@google.com> >> >> Ended up-in net-next as: >> >> commit 40931b85113dad7881d49e8759e5ad41d30a5e6c >> Author: Eric Dumazet <eduma...@google.com> >> Date: Fri Nov 25 07:46:20 2016 -0800 >> >> mlx4: give precise rx/tx bytes/packets counters >> >> mlx4 stats are chaotic because a deferred work queue is responsible >> to update them every 250 ms. >> >> Likely after this patch I get this crash (below), when rebooting my machine. >> Looks like a device removal order thing. >> Tested with net-next at commit 93ba22225504. >> >> [...] >> [ 1967.248453] mlx5_core 0000:02:00.1: Shutdown was called >> [ 1967.854556] mlx5_core 0000:02:00.0: Shutdown was called >> [ 1968.443015] e1000e: EEE TX LPI TIMER: 00000011 >> [ 1968.484676] sd 3:0:0:0: [sda] Synchronizing SCSI cache >> [ 1968.528354] mlx4_core 0000:01:00.0: mlx4_shutdown was called >> [ 1968.534054] mlx4_en: mlx4p1: Close port called >> [ 1968.571156] mlx4_en 0000:01:00.0: removed PHC >> [ 1968.575677] mlx4_en: mlx4p2: Close port called >> [ 1969.506602] BUG: unable to handle kernel NULL pointer dereference at >> 0000000000000d08 >> [ 1969.514530] IP: [<ffffffffa0127ca4>] >> mlx4_en_fold_software_stats.part.1+0x34/0xb0 [mlx4_en] >> [ 1969.522963] PGD 0 [ 1969.524803] >> [ 1969.526332] Oops: 0000 [#1] PREEMPT SMP >> [ 1969.530201] Modules linked in: coretemp kvm_intel kvm irqbypass >> intel_cstate mxm_wmi i2c_i801 intel_rapl_perf i2c_smbus sg pcspkr i2c_core >> shpchp nfsd wmi video acpi_pad auth_rpcgss oid_registry nfs_acl lockd grace >> sunrpc ip_tables x_tables mlx4_en e1000e mlx5_core ptp serio_raw sd_mod >> mlx4_core pps_core devlink hid_generic >> [ 1969.559616] CPU: 3 PID: 3104 Comm: kworker/3:1 Not tainted >> 4.9.0-rc6-net-next3-01390-g93ba22225504 #12 >> [ 1969.568984] Hardware name: To Be Filled By O.E.M. To Be Filled By >> O.E.M./Z97 Extreme4, BIOS P2.10 05/12/2015 >> [ 1969.578877] Workqueue: events linkwatch_event >> [ 1969.583285] task: ffff8803f42a0000 task.stack: ffff88040b2d0000 >> [ 1969.589238] RIP: 0010:[<ffffffffa0127ca4>] [<ffffffffa0127ca4>] >> mlx4_en_fold_software_stats.part.1+0x34/0xb0 [mlx4_en] >> [ 1969.600102] RSP: 0018:ffff88040b2d3bd8 EFLAGS: 00010282 >> [ 1969.605442] RAX: ffff8803f432efc8 RBX: ffff8803f4320000 RCX: >> 0000000000000000 >> [ 1969.612604] RDX: 0000000000000000 RSI: 0000000000000000 RDI: >> ffff8803f4320000 >> [ 1969.619772] RBP: ffff88040b2d3bd8 R08: 000000000000000c R09: >> ffff8803f432f000 >> [ 1969.626938] R10: 0000000000000000 R11: ffff88040d64ac00 R12: >> ffff8803e5aff8dc >> [ 1969.634104] R13: ffff8803f4320a28 R14: ffff8803e5aff800 R15: >> 0000000000000000 >> [ 1969.641273] FS: 0000000000000000(0000) GS:ffff88041fac0000(0000) >> knlGS:0000000000000000 >> [ 1969.649422] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> [ 1969.655197] CR2: 0000000000000d08 CR3: 0000000001c07000 CR4: >> 00000000001406e0 >> [ 1969.662366] Stack: >> [ 1969.664412] ffff88040b2d3be8 ffffffffa0127f8e ffff88040b2d3c10 >> ffffffffa012a23b >> [ 1969.671948] ffff8803e5aff8dc ffff8803f4320000 ffff8803f4320000 >> ffff88040b2d3c30 >> [ 1969.679478] ffffffff8160ae29 ffff8803e5aff8d8 ffff8804088ff300 >> ffff88040b2d3c58 >> [ 1969.687001] Call Trace: >> [ 1969.689484] [<ffffffffa0127f8e>] mlx4_en_fold_software_stats+0x1e/0x20 >> [mlx4_en] >> [ 1969.697026] [<ffffffffa012a23b>] mlx4_en_get_stats64+0x2b/0x50 [mlx4_en] >> [ 1969.703844] [<ffffffff8160ae29>] dev_get_stats+0x39/0xa0 >> [ 1969.709274] [<ffffffff81622470>] rtnl_fill_stats+0x40/0x130 >> [ 1969.714968] [<ffffffff8162631b>] rtnl_fill_ifinfo+0x55b/0x1010 >> [ 1969.720921] [<ffffffff816285d3>] rtmsg_ifinfo_build_skb+0x73/0xd0 >> [ 1969.727136] [<ffffffff81628646>] rtmsg_ifinfo.part.25+0x16/0x50 >> [ 1969.733176] [<ffffffff81628698>] rtmsg_ifinfo+0x18/0x20 >> [ 1969.738522] [<ffffffff8160e947>] netdev_state_change+0x47/0x50 >> [ 1969.744478] [<ffffffff81629018>] linkwatch_do_dev+0x38/0x50 >> [ 1969.750170] [<ffffffff81629257>] __linkwatch_run_queue+0xe7/0x160 >> [ 1969.756385] [<ffffffff816292f5>] linkwatch_event+0x25/0x30 >> [ 1969.761991] [<ffffffff8107b3cb>] process_one_work+0x15b/0x460 >> [ 1969.767857] [<ffffffff8107b71e>] worker_thread+0x4e/0x480 >> [ 1969.773378] [<ffffffff8107b6d0>] ? process_one_work+0x460/0x460 >> [ 1969.779420] [<ffffffff8107b6d0>] ? process_one_work+0x460/0x460 >> [ 1969.785460] [<ffffffff810811ea>] kthread+0xca/0xe0 >> [ 1969.790372] [<ffffffff81081120>] ? kthread_worker_fn+0x120/0x120 >> [ 1969.796495] [<ffffffff817302d2>] ret_from_fork+0x22/0x30 >> [ 1969.801924] Code: 00 00 55 48 89 e5 85 d2 0f 84 90 00 00 00 83 ea 01 31 >> c9 31 f6 48 8d 87 c0 ef 00 00 4c 8d 8c d7 c8 ef 00 00 48 8b 10 48 83 c0 08 >> <4c> 8b 82 08 0d 00 00 48 8b 92 00 0d 00 00 4c 01 c6 48 01 d1 4c >> [ 1969.821969] RIP [<ffffffffa0127ca4>] >> mlx4_en_fold_software_stats.part.1+0x34/0xb0 [mlx4_en] >> [ 1969.830486] RSP <ffff88040b2d3bd8> >> [ 1969.834002] CR2: 0000000000000d08 >> [ 1969.837440] ---[ end trace 80b9fbc1e7baed9b ]--- >> [ 1969.842102] Kernel panic - not syncing: Fatal exception in interrupt >> [ 1969.848520] Kernel Offset: disabled >> [ 1969.852050] ---[ end Kernel panic - not syncing: Fatal exception in >> interrupt >> (END) > > Hi Jesper. > > Thanks for the report. > > Then we have a bug in the driver, deleting some memory too soon.
No ! it always been this way, the cached stats are always there (never deleted). we just stop caching once the device is down, nothing is deleted too soon. > > If we depend on having proper stats at device dismantle, we need to keep we had/still have the proper stats they are the ones that mlx4_en_fold_software_stats is trying to cache into (they always exist), but the ones that you are trying to read from (the mlx4 rings) are gone ! This bug is totally new and as i warned, this is another symptom of the real root cause (can't sleep while reading stats). Eric what do you suggest ? Keep pre-allocated MAX_RINGS stats and always iterate over all of them to query stats ? what if you have one ring/none/1K ? how would you know how many to query ?
