Re: KASAN error when insmod cxl_test

["Zhijian Li (Fujitsu)" <lizhijian@fujitsu.com>]

All,

I encountered a panic with similar calltrace

I guessed I have root cause this, it was introduced since commit

commit a5ab0de0ebaa65e0a75ec0761a2745c66a9d17dc
Author: Dave Jiang <dave.jiang@intel.com>
Date:   Tue Sep 3 17:11:51 2024 -0700

     cxl: Calculate region bandwidth of targets with shared upstream link


Which calls cxl_region_shared_upstream_bandwidth_update(cxlr).
However, the cxl_region_shared_upstream_bandwidth_update(cxlr) works on PCI/PCIE device only
while the cxl_test was implemented by platform device.

I'm cooking and testing below patch

index ef1621d40f05..3eb27cfe43ed 100644
--- a/drivers/cxl/core/cdat.c
+++ b/drivers/cxl/core/cdat.c
@@ -5,6 +5,7 @@
  #include <linux/fw_table.h>
  #include <linux/node.h>
  #include <linux/overflow.h>
+#include <linux/platform_device.h>
  #include "cxlpci.h"
  #include "cxlmem.h"
  #include "core.h"
@@ -641,9 +642,13 @@ static int cxl_endpoint_gather_bandwidth(struct cxl_region *cxlr,
         void *ptr;
         int rc;

         if (cxlds->rcd)
                 return -ENODEV;
  
+       if (dev_is_platform(cxlds->dev))
+               return -ENODEV;
+

=======================
reproducer:
$ while true; do meson test cxl-create-region.sh; done

====================
[ 1174.878672] platform cxl_host_bridge.3: host supports CXL (restricted)
[ 1175.532274] Oops: general protection fault, probably for non-canonical address 0x3ef17856fcae4fbd: 0000 [#1] PREEMPT SMP PTI
[ 1175.532300] CPU: 1 UID: 0 PID: 9167 Comm: cxl Kdump: loaded Tainted: G           OE      6.12.0-rc3-master+ #66
[ 1175.532316] Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE
[ 1175.532325] Hardware name: LENOVO 90CXCTO1WW/, BIOS FCKT70AUS 04/23/2015
[ 1175.532335] RIP: 0010:pci_bus_read_config_word+0x1c/0x60
[ 1175.532346] Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 53 b8 87 00 00 00 48 83 ec 08 c7 44 24 04 00 00 00 00 f6 c2 01 75 29 <48> 8b 87 c0 00 00 00 48 89 cb 4c 8d 44 24 04 b9 02 00 00 00 48 8b
[ 1175.532370] RSP: 0018:ffffa115034dfbb8 EFLAGS: 00010246
[ 1175.532379] RAX: 0000000000000087 RBX: 0000000000000012 RCX: ffffa115034dfbfe
[ 1175.532390] RDX: 0000000000000016 RSI: 000000006f4e2f4e RDI: 3ef17856fcae4efd
[ 1175.532401] RBP: ffff8cc229121b48 R08: 0000000000000010 R09: 0000000000000000
[ 1175.532412] R10: 0000000000000001 R11: ffff8cc225434360 R12: ffffa115034dfbfe
[ 1175.532422] R13: 0000000000000000 R14: ffff8cc2f119a080 R15: ffffa115034dfc50
[ 1175.532433] FS:  00007f31d93537c0(0000) GS:ffff8cc510a80000(0000) knlGS:0000000000000000
[ 1175.532445] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1175.532455] CR2: 00007f31d95f3370 CR3: 00000001163ea001 CR4: 00000000001726f0
[ 1175.532465] Call Trace:
[ 1175.532472]  <TASK>
[ 1175.532478]  ? __die_body.cold+0x19/0x27
[ 1175.532488]  ? die_addr+0x38/0x60
[ 1175.532496]  ? exc_general_protection+0x1f5/0x4b0
[ 1175.532507]  ? asm_exc_general_protection+0x22/0x30
[ 1175.532519]  ? pci_bus_read_config_word+0x1c/0x60
[ 1175.532528]  pcie_capability_read_word+0x93/0xb0
[ 1175.532538]  pcie_link_speed_mbps+0x18/0x50
[ 1175.532548]  cxl_pci_get_bandwidth+0x18/0x60 [cxl_core]
[ 1175.532575]  cxl_endpoint_gather_bandwidth.constprop.0+0xf4/0x230 [cxl_core]
[ 1175.532596]  ? xas_store+0x54/0x660
[ 1175.532605]  ? preempt_count_add+0x69/0xa0
[ 1175.532615]  ? _raw_spin_lock+0x13/0x40
[ 1175.532623]  ? __kmalloc_cache_noprof+0xe7/0x270
[ 1175.532632]  cxl_region_shared_upstream_bandwidth_update+0x9c/0x790 [cxl_core]
[ 1175.532653]  cxl_region_attach+0x520/0x7e0 [cxl_core]
[ 1175.532672]  store_targetN+0xf2/0x120 [cxl_core]
[ 1175.532690]  kernfs_fop_write_iter+0x13a/0x1f0
[ 1175.532699]  vfs_write+0x23b/0x410
[ 1175.532707]  ksys_write+0x53/0xd0
[ 1175.532714]  do_syscall_64+0x62/0x180
[ 1175.532724]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
[ 1175.532734] RIP: 0033:0x7f31d9611834
[ 1175.532742] Code: c7 00 16 00 00 00 b8 ff ff ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 f3 0f 1e fa 80 3d 15 f8 0d 00 00 74 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 55 48 89 e5 48 83 ec 20 48 89
[ 1175.532764] RSP: 002b:00007ffc382f7ff8 EFLAGS: 00000202 ORIG_RAX: 0000000000000001
[ 1175.532776] RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 00007f31d9611834
[ 1175.532787] RDX: 000000000000000c RSI: 000000003ed90593 RDI: 0000000000000003
[ 1175.532797] RBP: 00007ffc382f8030 R08: 0000000000000064 R09: 00000000ffffffff
[ 1175.532808] R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000006
[ 1175.532818] R13: 0000000000000000 R14: 00007f31d97c4000 R15: 0000000000428d80
[ 1175.532830]  </TASK>
[ 1175.532835] Modules linked in: device_dax(OE) kmem dax_cxl cxl_mock_mem(OE) cxl_test(OE) cxl_mem(OE) cxl_port(OE) cxl_pmem(OE) cxl_acpi(OE) cxl_mock(OE) cxl_core(OE) xt_CHECKSUM xt_MASQUERADE xt_conntrack ipt_REJECT nf_nat_tftp nf_conntrack_tftp bridge stp llc nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat ip6table_nat ip6table_mangle ip6table_raw ip6table_security iptable_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 iptable_mangle iptable_raw iptable_security ip_set nf_tables ip6table_filter iptable_filter rfkill intel_rapl_msr intel_rapl_common sunrpc x86_pkg_temp_thermal snd_hda_codec_realtek intel_powerclamp snd_hda_codec_generic coretemp snd_hda_scodec_component kvm_intel snd_hda_codec_hdmi snd_hda_intel snd_intel_dspcfg snd_hda_codec kvm snd_hwdep snd_hda_core snd_seq snd_seq_device snd_pcm snd_timer snd rapl mei_hdcp intel_cstate soundcore iTCO_wdt mei_me at24 intel_pmc_bxt intel_uncore iTCO_vendor_support i2c_i801 wmi_bmof
[ 1175.532885]  pcspkr mei i2c_smbus lpc_ich loop nfnetlink zram xfs i915 i2c_algo_bit drm_buddy ttm drm_display_helper dax_pmem(OE) nd_pmem(OE) nd_btt(OE) drm_kms_helper nd_e820(OE) libnvdimm(OE) crct10dif_pclmul crc32_pclmul crc32c_intel ghash_clmulni_intel drm nfit_test_iomap(OE) r8169 video wmi serio_raw ip6_tables ip_tables pkcs8_key_parser fuse
[ 1175.533043] ---[ end trace 0000000000000000 ]---
[ 1175.533055] RIP: 0010:pci_bus_read_config_word+0x1c/0x60
[ 1175.533065] Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 53 b8 87 00 00 00 48 83 ec 08 c7 44 24 04 00 00 00 00 f6 c2 01 75 29 <48> 8b 87 c0 00 00 00 48 89 cb 4c 8d 44 24 04 b9 02 00 00 00 48 8b
[ 1175.533088] RSP: 0018:ffffa115034dfbb8 EFLAGS: 00010246
[ 1175.533097] RAX: 0000000000000087 RBX: 0000000000000012 RCX: ffffa115034dfbfe
[ 1175.533108] RDX: 0000000000000016 RSI: 000000006f4e2f4e RDI: 3ef17856fcae4efd
[ 1175.533119] RBP: ffff8cc229121b48 R08: 0000000000000010 R09: 0000000000000000
[ 1175.533840] R10: 0000000000000001 R11: ffff8cc225434360 R12: ffffa115034dfbfe
[ 1175.534567] R13: 0000000000000000 R14: ffff8cc2f119a080 R15: ffffa115034dfc50
[ 1175.535295] FS:  00007f31d93537c0(0000) GS:ffff8cc510a80000(0000) knlGS:0000000000000000
[ 1175.536015] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1175.536720] CR2: 00007f31d95f3370 CR3: 00000001163ea001 CR4: 00000000001726f0
[ 1176.146160] PEFILE: Unsigned PE binary


Thanks
Zhijian



On 10/10/2024 17:03, Huang, Ying wrote:
> Hi, Dave,
> 
> When I tried to test v6.12-rc2 with cxl_test in qemu, the below error is
> reported.  Revert commit a5ab0de0ebaa ("cxl: Calculate region bandwidth
> of targets with shared upstream link") can eliminate the error.
> 
> Can you take a look at it?
> 
> The kernel config used to build kernel is attached.
> 
> -----------------------------8<------------------------------
> [   28.103428] ==================================================================
> [   28.104078] BUG: KASAN: slab-out-of-bounds in pcie_capability_reg_implemented+0x18/0xfb
> [   28.104635] Read of size 1 at addr ffff888008a79fb4 by task systemd-udevd/408
> [   28.105137]
> [   28.105261] CPU: 4 UID: 0 PID: 408 Comm: systemd-udevd Tainted: G           O       6.12.0-rc2-kvm #5
> [   28.105868] Tainted: [O]=OOT_MODULE
> [   28.106201] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
> [   28.107115] Call Trace:
> [   28.107339]  <TASK>
> [   28.107526]  dump_stack_lvl+0x65/0x8c
> [   28.107803]  print_address_description.constprop.0+0x8a/0x309
> [   28.108223]  print_report+0x136/0x20f
> [   28.108493]  ? kmem_cache_debug_flags+0x16/0x23
> [   28.108836]  ? fixup_red_left+0x17/0x27
> [   28.109262]  ? pcie_capability_reg_implemented+0x18/0xfb
> [   28.109806]  kasan_report+0x85/0xa7
> [   28.110184]  ? pcie_capability_reg_implemented+0x18/0xfb
> [   28.110693]  pcie_capability_reg_implemented+0x18/0xfb
> [   28.111211]  pcie_capability_read_word+0x38/0xaa
> [   28.111653]  ? __free_kfree+0x9/0x22 [cxl_core]
> [   28.112194]  pcie_link_speed_mbps+0x54/0xae
> [   28.112594]  ? pcie_get_mps+0x6d/0x6d
> [   28.113037]  cxl_pci_get_bandwidth+0x58/0xd3 [cxl_core]
> [   28.113645]  ? cxl_pci_get_latency+0xac/0xac [cxl_core]
> [   28.114192]  ? _raw_spin_unlock+0x1f/0x2f
> [   28.114683]  ? xa_store+0x3b/0x45
> [   28.115109]  cxl_endpoint_gather_bandwidth.constprop.0+0x2bf/0x352 [cxl_core]
> [   28.116017]  ? cxl_hb_gather_bandwidth+0x205/0x205 [cxl_core]
> [   28.116967]  ? __module_address+0xe7/0xff
> [   28.117673]  ? is_module_address+0x11/0x26
> [   28.118419]  ? static_obj+0x7f/0x90
> [   28.119016]  ? lockdep_init_map_type+0x22e/0x305
> [   28.120557]  ? __raw_spin_lock_init+0x73/0x83
> [   28.121707]  cxl_region_shared_upstream_bandwidth_update+0x12c/0x491 [cxl_core]
> [   28.123434]  ? cxl_endpoint_gather_bandwidth.constprop.0+0x352/0x352 [cxl_core]
> [   28.124622]  ? check_last_peer+0x228/0x2c5 [cxl_core]
> [   28.125273]  ? xa_set_mark+0x34/0x34
> [   28.125717]  ? cxl_region_setup_targets+0x3a/0x1b8 [cxl_core]
> [   28.126417]  cxl_region_attach+0x8cb/0xb05 [cxl_core]
> [   28.127049]  attach_target+0x49/0x6f [cxl_core]
> [   28.127631]  cxl_add_to_region+0x15a/0x1d6 [cxl_core]
> [   28.128262]  ? schedule_detach+0xa/0xa [cxl_port]
> [   28.128790]  discover_region+0x5d/0xb6 [cxl_port]
> [   28.129327]  ? next_device+0x20/0x2d
> [   28.129767]  device_for_each_child+0x8f/0xc0
> [   28.130243]  ? next_device+0x2d/0x2d
> [   28.130644]  ? kobject_get+0x47/0x75
> [   28.131051]  cxl_port_probe+0x19f/0x272 [cxl_port]
> [   28.131573]  ? discover_region+0xb6/0xb6 [cxl_port]
> [   28.132117]  ? kernfs_put+0x19/0x2b
> [   28.132509]  ? sysfs_do_create_link_sd+0x7a/0xbc
> [   28.133016]  cxl_bus_probe+0x27/0x54 [cxl_core]
> [   28.133611]  ? really_probe+0x194/0x43d
> [   28.134064]  really_probe+0x1e4/0x43d
> [   28.134483]  ? driver_probe_device+0xc0/0xc0
> [   28.134969]  driver_probe_device+0x4a/0xc0
> [   28.135430]  __device_attach_driver+0xd7/0x102
> [   28.135932]  bus_for_each_drv+0xf2/0x116
> [   28.136374]  ? bus_rescan_devices+0x15/0x15
> [   28.136849]  __device_attach+0x10c/0x19c
> [   28.137300]  ? device_bind_driver+0x39/0x39
> [   28.137787]  ? bus_to_subsys+0xad/0xb9
> [   28.138213]  bus_probe_device+0x4e/0xd3
> [   28.138656]  device_add+0x55b/0x791
> [   28.139056]  ? get_device_parent+0x20a/0x20a
> [   28.139539]  ? rcu_read_unlock+0x51/0x5b
> [   28.139996]  devm_cxl_add_port+0x20a/0x49c [cxl_core]
> [   28.140642]  ? cxl_port_alloc+0x430/0x430 [cxl_core]
> [   28.141271]  cxl_mem_probe+0x3b9/0x47c [cxl_mem]
> [   28.141806]  ? __devm_add_action_or_reset+0x26/0x26 [cxl_mem]
> [   28.142447]  ? sysfs_do_create_link_sd+0x7a/0xbc
> [   28.142969]  cxl_bus_probe+0x27/0x54 [cxl_core]
> [   28.143540]  ? really_probe+0x194/0x43d
> [   28.143999]  really_probe+0x1e4/0x43d
> [   28.144418]  ? driver_probe_device+0xc0/0xc0
> [   28.144902]  driver_probe_device+0x4a/0xc0
> [   28.145353]  __device_attach_driver+0xd7/0x102
> [   28.145629]  bus_for_each_drv+0xf2/0x116
> [   28.145865]  ? bus_rescan_devices+0x15/0x15
> [   28.146115]  __device_attach+0x10c/0x19c
> [   28.146351]  ? device_bind_driver+0x39/0x39
> [   28.146614]  ? bus_to_subsys+0xad/0xb9
> [   28.146839]  bus_probe_device+0x4e/0xd3
> [   28.147069]  device_add+0x55b/0x791
> [   28.147306]  ? get_device_parent+0x20a/0x20a
> [   28.147568]  ? kobject_get+0x47/0x75
> [   28.147784]  cdev_device_add+0x31/0x89
> [   28.148015]  devm_cxl_add_memdev+0x26e/0x2d7 [cxl_core]
> [   28.148369]  cxl_mock_mem_probe+0x2f3/0x33b [cxl_mock_mem]
> [   28.148694]  platform_probe+0x3d/0x7a
> [   28.148914]  really_probe+0x1e4/0x43d
> [   28.149133]  ? __device_attach_driver+0x102/0x102
> [   28.149420]  driver_probe_device+0x4a/0xc0
> [   28.149669]  __driver_attach+0x19c/0x1bb
> [   28.149912]  bus_for_each_dev+0xc7/0x101
> [   28.150152]  ? bus_register+0x2d4/0x2d4
> [   28.150387]  ? bus_add_driver+0x137/0x2cc
> [   28.150648]  bus_add_driver+0x19d/0x2cc
> [   28.150881]  driver_register+0x12c/0x17d
> [   28.151111]  ? 0xffffffffc0ac8000
> [   28.151307]  do_one_initcall+0x139/0x2da
> [   28.151538]  ? rcu_lock_acquire.constprop.0+0x25/0x25
> [   28.151826]  ? unpoison_slab_object+0x1b/0x38
> [   28.152100]  ? __kasan_slab_alloc+0x37/0x41
> [   28.152342]  ? rcu_is_watching+0x1c/0x38
> [   28.152572]  ? poison_kmalloc_redzone+0x44/0x65
> [   28.152835]  ? kasan_unpoison+0x26/0x31
> [   28.153058]  ? __asan_register_globals+0x55/0x60
> [   28.153338]  do_init_module+0x118/0x388
> [   28.153576]  init_module_from_file+0xc2/0xe4
> [   28.153838]  ? __ia32_sys_init_module+0x40/0x40
> [   28.154127]  ? do_raw_spin_unlock+0xce/0xd6
> [   28.154370]  idempotent_init_module+0x1ea/0x3c0
> [   28.154634]  ? init_module_from_file+0xe4/0xe4
> [   28.154892]  ? __seccomp_filter+0xf5/0x4f2
> [   28.155135]  ? files_lookup_fd_raw+0x40/0x4b
> [   28.155386]  __do_sys_finit_module+0x68/0x82
> [   28.155636]  do_syscall_64+0x9a/0xfd
> [   28.155848]  entry_SYSCALL_64_after_hwframe+0x4b/0x53
> [   28.156145] RIP: 0033:0x7f2239ce4559
> [   28.156355] Code: 08 89 e8 5b 5d c3 66 2e 0f 1f 84 00 00 00 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 77 08 0d 00 f7 d8 64 89 01 48
> [   28.157428] RSP: 002b:00007fffd30e95d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
> [   28.157858] RAX: ffffffffffffffda RBX: 000055fd0ed12110 RCX: 00007f2239ce4559
> [   28.158260] RDX: 0000000000000000 RSI: 00007f2239e67e2d RDI: 0000000000000006
> [   28.158661] RBP: 0000000000020000 R08: 0000000000000000 R09: 000055fd0ed13b28
> [   28.159063] R10: 0000000000000006 R11: 0000000000000246 R12: 00007f2239e67e2d
> [   28.159465] R13: 0000000000000000 R14: 000055fd0ed13180 R15: 000055fd0ed12110
> [   28.159870]  </TASK>
> [   28.160003]
> [   28.160098] Allocated by task 385:
> [   28.160298]  stack_trace_save+0x7c/0x94
> [   28.160523]  kasan_save_stack+0x1c/0x34
> [   28.160763]  kasan_save_track+0x10/0x25
> [   28.160997]  __kasan_kmalloc+0x3a/0x43
> [   28.161222]  __kmalloc_node_track_caller_noprof+0x1fd/0x22d
> [   28.161562]  kmalloc_reserve+0xe6/0x130
> [   28.161797]  __alloc_skb+0x109/0x1b8
> [   28.162018]  alloc_uevent_skb+0x55/0xe2
> [   28.162254]  kobject_uevent_net_broadcast+0x11d/0x265
> [   28.162565]  kobject_uevent_env+0x534/0x6d3
> [   28.162806]  device_add+0x4da/0x791
> [   28.163011]  platform_device_add+0x248/0x2dd
> [   28.163258]  0xffffffffc0b40708
> [   28.163446]  do_one_initcall+0x139/0x2da
> [   28.163673]  do_init_module+0x118/0x388
> [   28.163933]  init_module_from_file+0xc2/0xe4
> [   28.164312]  idempotent_init_module+0x1ea/0x3c0
> [   28.164665]  __do_sys_finit_module+0x68/0x82
> [   28.164992]  do_syscall_64+0x9a/0xfd
> [   28.165295]  entry_SYSCALL_64_after_hwframe+0x4b/0x53
> [   28.165634]
> [   28.165767] Freed by task 168:
> [   28.165968]  stack_trace_save+0x7c/0x94
> [   28.166207]  kasan_save_stack+0x1c/0x34
> [   28.166442]  kasan_save_track+0x10/0x25
> [   28.166669]  kasan_save_free_info+0x3b/0x41
> [   28.166912]  __kasan_slab_free+0x18/0x2a
> [   28.167150]  kfree+0x206/0x26a
> [   28.167388]  skb_release_data+0x152/0x16e
> [   28.167636]  __kfree_skb+0x14/0x1e
> [   28.167834]  netlink_recvmsg+0x2b2/0x503
> [   28.168066]  sock_recvmsg_nosec+0x48/0x80
> [   28.168305]  ____sys_recvmsg+0x10c/0x1fa
> [   28.168542]  ___sys_recvmsg+0xc7/0x103
> [   28.168762]  __sys_recvmsg+0xb7/0x113
> [   28.168978]  do_syscall_64+0x9a/0xfd
> [   28.169188]  entry_SYSCALL_64_after_hwframe+0x4b/0x53
> [   28.169504]
> [   28.169599] The buggy address belongs to the object at ffff888008a79800
> [   28.169599]  which belongs to the cache kmalloc-1k of size 1024
> [   28.170285] The buggy address is located 948 bytes to the right of
> [   28.170285]  allocated 1024-byte region [ffff888008a79800, ffff888008a79c00)
> [   28.171055]
> [   28.171152] The buggy address belongs to the physical page:
> [   28.171487] page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff888008a7f800 pfn:0x8a78
> [   28.172060] head: order:3 mapcount:0 entire_mapcount:0 nr_pages_mapped:0 pincount:0
> [   28.172539] flags: 0xffffc000000240(workingset|head|node=0|zone=1|lastcpupid=0x1ffff)
> [   28.173104] page_type: f5(slab)
> [   28.173343] raw: 00ffffc000000240 ffff888001042dc0 ffffea0000226410 ffffea00002f3010
> [   28.173822] raw: ffff888008a7f800 0000000000100008 00000001f5000000 0000000000000000
> [   28.174308] head: 00ffffc000000240 ffff888001042dc0 ffffea0000226410 ffffea00002f3010
> [   28.174733] head: ffff888008a7f800 0000000000100008 00000001f5000000 0000000000000000
> [   28.175177] head: 00ffffc000000003 ffffea0000229e01 ffffffffffffffff 0000000000000000
> [   28.175631] head: 0000000000000008 0000000000000000 00000000ffffffff 0000000000000000
> [   28.176074] page dumped because: kasan: bad access detected
> [   28.176391]
> [   28.176484] Memory state around the buggy address:
> [   28.176746]  ffff888008a79e80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> [   28.177121]  ffff888008a79f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> [   28.177612] >ffff888008a79f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> [   28.178011]                                      ^
> [   28.178286]  ffff888008a7a000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> [   28.178671]  ffff888008a7a080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> [   28.179183] ==================================================================
> 
> --
> Best Regards,
> Huang, Ying