Hello Anil & Co, On Tue, 2016-10-25 at 05:33 +0000, Gurumurthy, Anil wrote: > On Mon, 2016-10-24 at 06:36 +0000, Anil Gurumurthy wrote: <SNIP> > > > > [71884.588748] BUG: unable to handle kernel NULL pointer dereference > > at 00000000000000e0 > > > > [71884.588881] IP: [<ffffffff811ff52a>] kmem_cache_free+0x11a/0x200 > > > > [71884.588981] PGD 0 > > > > [71884.589017] Oops: 0000 [#1] SMP > > > > [71884.589041] ------------[ cut here ]------------ > > > > [71884.589048] WARNING: CPU: 2 PID: 20783 at lib/list_debug.c:62 > > __list_del_entry+0x86/0xd0 > > > > [71884.589049] list_del corruption. next->prev should be > > ffff8806f8daeb68, but was ffff8806f8db79e8 > > > > [71884.589075] Modules linked in: target_core_pscsi tcm_qla2xxx(OE) > > qla2xxx(OE) iscsi_target_mod target_core_file target_core_iblock > > target_core_mod netconsole ebtable_nat ebtables ipt_MASQUERADE > > nf_nat_masquerade_ipv4 iptable_nat nf_nat_ipv4 nf_nat xt_CHECKSUM > > iptable_mangle bridge 8021q mrp garp stp llc ipt_REJECT nf_reject_ipv4 > > nf_conntrack_ipv4 nf_defrag_ipv4 iptable_filter ip_tables ip6t_REJECT > > nf_reject_ipv6 nf_conntrack_ipv6 nf_defrag_ipv6 xt_state nf_conntrack > > ip6table_filter ip6_tables binfmt_misc vhost_net macvtap macvlan vhost > > tun uinput sg serio_raw iTCO_wdt iTCO_vendor_support ipmi_ssif ipmi_si > > ipmi_msghandler hpilo hpwdt bnx2 intel_powerclamp coretemp kvm_intel > > kvm irqbypass crct10dif_pclmul crc32_pclmul crc32c_intel > > ghash_clmulni_intel pcspkr acpi_power_meter lpc_ich mfd_core > > i7core_edac edac_core shpchp ext4(E) mbcache(E) jbd2(E) sd_mod(E) > > sr_mod(E) cdrom(E) scsi_transport_fc(E) hpsa(E) scsi_transport_sas(E) > > aesni_intel(E) ablk_helper(E) cryptd(E) lrw(E) gf128mul(E) > > glue_helper(E) pata_acpi(E) ata_generic(E) ata_piix(E) libata(E) > > radeon(E) ttm(E) drm_kms_helper(E) drm(E) fb_sys_fops(E) sysimgblt(E) > > sysfillrect(E) syscopyarea(E) i2c_algo_bit(E) i2c_core(E) dm_mirror(E) > > dm_region_hash(E) dm_log(E) dm_mod(E) [last unloaded: qla2xxx] > > > > [71884.589091] CPU: 2 PID: 20783 Comm: kworker/2:0 Tainted: G W > > IOE 4.7.0-rc1+ #2 > > > > [71884.589092] Hardware name: HP ProLiant DL380 G7, BIOS P67 > > 05/05/2011 > > > > [71884.589107] Workqueue: target_completion target_complete_ok_work > > [target_core_mod] > > > > [71884.589109] 0000000000000000 ffff880408d1fae8 ffffffff81352197 > > ffffffff81370ef6 > > > > [71884.589110] ffff880408d1fb48 ffff880408d1fb48 0000000000000000 > > ffff880408d1fb38 > > > > [71884.589111] ffffffff8108a12d 00000000000007c3 0000003e00000246 > > 0000000000000246 > > > > [71884.589112] Call Trace: > > > > [71884.589115] [<ffffffff81352197>] dump_stack+0x67/0x90 > > > > [71884.589117] [<ffffffff81370ef6>] ? __list_del_entry+0x86/0xd0 > > > > [71884.589119] [<ffffffff8108a12d>] __warn+0xfd/0x120 > > > > [71884.589120] [<ffffffff8108a209>] warn_slowpath_fmt+0x49/0x50 > > > > [71884.589122] [<ffffffff81370ef6>] __list_del_entry+0x86/0xd0 > > > > [71884.589123] [<ffffffff81370f51>] list_del+0x11/0x40 > > > > [71884.589132] [<ffffffffa0799d1e>] target_remove_from_state_list > > +0x6e/0x80 [target_core_mod] > > > > [71884.589140] [<ffffffffa0799e14>] transport_cmd_check_stop > > +0xe4/0x120 [target_core_mod] > > > > [71884.589151] [<ffffffffa0799e65>] > > transport_cmd_check_stop_to_fabric+0x15/0x20 [target_core_mod] > > > > [71884.589160] [<ffffffffa079dbfe>] target_complete_ok_work > > +0x14e/0x280 [target_core_mod] > > > > [71884.589162] [<ffffffff810a39c0>] ? pwq_dec_nr_in_flight+0x50/0xa0 > > > > [71884.589164] [<ffffffff810a4703>] process_one_work+0x183/0x4d0 > > > > [71884.589166] [<ffffffff816d913f>] ? __schedule+0x1ff/0x5c0 > > > > [71884.589167] [<ffffffff816d9600>] ? schedule+0x40/0xb0 > > > > [71884.589169] [<ffffffff810a53bd>] worker_thread+0x16d/0x530 > > > > [71884.589171] [<ffffffff8102eb1d>] ? __switch_to+0x1cd/0x5e0 > > > > [71884.589173] [<ffffffff816d913f>] ? __schedule+0x1ff/0x5c0 > > > > [71884.589175] [<ffffffff810cc586>] ? __wake_up_common+0x56/0x90 > > > > [71884.589177] [<ffffffff810a5250>] ? maybe_create_worker+0x120/0x120 > > > > [71884.589178] [<ffffffff816d9600>] ? schedule+0x40/0xb0 > > > > [71884.589179] [<ffffffff810a5250>] ? maybe_create_worker+0x120/0x120 > > > > [71884.589180] [<ffffffff810a9fcc>] kthread+0xcc/0xf0 > > > > [71884.589183] [<ffffffff81003f08>] ? do_syscall_64+0x78/0x1d0 > > > > [71884.589185] [<ffffffff810b49ee>] ? schedule_tail+0x1e/0xc0 > > > > [71884.589188] [<ffffffff816dd47f>] ret_from_fork+0x1f/0x40 > > > > [71884.589189] [<ffffffff810a9f00>] ? kthread_freezable_should_stop > > +0x70/0x70 > > > > [71884.589190] ---[ end trace 7f24d6c863b6e35b ]--- > > > > [71884.589204] ------------[ cut here ]------------ > > > > [71884.589206] WARNING: CPU: 2 PID: 20783 at lib/list_debug.c:59 > > __list_del_entry+0xa5/0xd0 > > > > > > Was list corruption preceded by hung kernel task warnings..? > > No. The only messages prior to them were similar to this: > [ 3345.864359] ABORT_TASK: Sending TMR_TASK_DOES_NOT_EXIST for ref_tag: 1219168 [ 3345.864378] qla2xxx [0000:0b:00.1]-e900:4: RESET-TMR online/active/old-count/new-count = 1/0/0/1. > [ 3345.864418] BUG: unable to handle kernel NULL pointer dereference at 00000000000000e0 [ 3345.864549] IP: [<ffffffff811ff52a>] kmem_cache_free+0x11a/0x200 > Thanks for confirming. The ABORT_TASK TMR_TASK_DOES_NOT_EXIST exceptions here do not depend on the missing SCF_ACK_KREF bit assignment. The earlier SCF_ACK_KREF reference leak fix is specific to TMR that reference active se_cmd->cmd_kref tags, when I/O is still outstanding to associated target-core se_cmd->se_dev backends. > > > > On this particular kernel version (4.7), I am unable to get a crash > > dump, so cannot really fathom whats going on. > > > > Note there is a v4.1+ reference leak regression for ABORT_TASK + session shutdown here: > > https://github.com/torvalds/linux/commit/527268df31e57cf2b6d417198717c6d6afdb1e3e > > > Have you seen or have been notified of this behaviour? > > TomK (CC') reported something similar using v4.8.4 with ESX hosts ABORT_TASK + tcm/qla2xxx ports. > > > Any ideas/thoughts on how to proceed? > > > > > > Currently unsure if this list corruption is related to the above regression, or not. > > Please verify using the patch on v4.7.y code during tcm/qla2xxx session shutdown -> restart, once ABORT_TASK has occurred. > [Anil] I see the issue even when I apply this patch to my kernel. > >From above + TomK's list corruption logs, it looks like a se_cmd->cmd_kref is prematurely reaching zero + freeing memory while se_cmd memory is still outstanding to target-core backend. The se_cmd->state_list is not used by TMR, so AFAICT list corruption here is specific to qla_tgt_cmd->se_cmd dispatched into target-core, released while se_cmd is still outstanding. To confirm verify the theory, please change the list_debug warn above into BUG_ON with LKCD logic in place, and let's have a look. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
