Hi, On Fri, 2017-10-06 at 07:37 -0700, Eric Dumazet wrote: > On Fri, 2017-10-06 at 14:57 +0200, Paolo Abeni wrote: > > Enabling CONFIG_RCU_NOREF_DEBUG gives the following splat when > > processing tcp packets: > > > > to-be-untracked noref entity ffff942cb71ea300 not found in cache > > ------------[ cut here ]------------ > > WARNING: CPU: 24 PID: 178 at kernel/rcu/noref_debug.c:54 > > rcu_track_noref+0xa4/0xf0 > > Modules linked in: intel_rapl sb_edac x86_pkg_temp_thermal > > intel_powerclamp coretemp kvm_intel kvm irqbypass crct10dif_pclmul > > crc32_pclmul ghash_clmulni_intel pcbc aesni_intel crypto_simd glue_helper > > cryptd iTCO_wdt ipmi_ssif mei_me iTCO_vendor_support mei dcdbas lpc_ich > > ipmi_si mxm_wmi sg pcspkr ipmi_devintf ipmi_msghandler acpi_power_meter > > shpchp wmi nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs > > libcrc32c sd_mod mgag200 drm_kms_helper syscopyarea sysfillrect sysimgblt > > fb_sys_fops ttm igb drm ixgbe mdio crc32c_intel ahci ptp i2c_algo_bit > > libahci pps_core i2c_core libata dca dm_mirror dm_region_hash dm_log dm_mod > > CPU: 24 PID: 178 Comm: ksoftirqd/24 Not tainted > > 4.14.0-rc1.noref_route+ #1610 > > Hardware name: Dell Inc. PowerEdge R730/072T6D, BIOS 2.4.3 > > 01/17/2017 > > task: ffff940e48300000 task.stack: ffffaec406a20000 > > RIP: 0010:rcu_track_noref+0xa4/0xf0 > > RSP: 0018:ffffaec406a238e0 EFLAGS: 00010246 > > RAX: 0000000000000040 RBX: 0000000000000000 RCX: 0000000000000002 > > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000292 > > RBP: ffffaec406a238e0 R08: 0000000000000000 R09: 0000000000000000 > > R10: 0000000000000001 R11: 0000000000000003 R12: 0000000000000000 > > R13: ffff942cb5110000 R14: 000000000000fe88 R15: ffff942cb1a20200 > > FS: 0000000000000000(0000) GS:ffff942cbee00000(0000) > > knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 00007febc072d140 CR3: 0000001feebd6002 CR4: 00000000003606e0 > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > Call Trace: > > tcp_data_queue+0x82a/0xce0 > > That is strange, since tcp_data_queue() starts with > > skb_dst_drop(skb); > > So this stack trace looks suspicious.
Thank you for the feedback. I most probably messed-up while extracting the info from dmsg, as this issue gives a couple of splats almost concurrently. Please let me re-do the test and post a more resonable dmsg. The problem with the current code is that in the tcp_rcv_established() -> tcp_queue_rcv() path, the skb_dst() is not cleared. Thanks, Paolo
