In below senario, kasan causes deadlock while reporting vm area informaion:

CPU0                                CPU1
vmalloc();
 alloc_vmap_area();
  spin_lock(&vn->busy.lock)
                                    spin_lock_bh(&some_lock);
   <interrupt occurs>
   <in softirq>
   spin_lock(&some_lock);
                                    <access invalid address>
                                    kasan_report();
                                     print_report();
                                      print_address_description();
                                       kasan_find_vm_area();
                                        find_vm_area();
                                         spin_lock(&vn->busy.lock) // deadlock!

To resolve this possible deadlock, don't call find_vm_area()
to prevent possible deadlock while kasan reports vm area information.

Fixes: c056a364e954 ("kasan: print virtual mapping info in reports")
Reported-by: Yunseong Kim <ysk@kzalloc.com>
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
---
Below report is from Yunseong Kim using DEPT:

===================================================
DEPT: Circular dependency has been detected.
6.15.0-rc6-00043-ga83a69ec7f9f #5 Not tainted
---------------------------------------------------
summary
---------------------------------------------------
*** DEADLOCK ***

context A
   [S] lock(report_lock:0)
   [W] lock(&vn->busy.lock:0)
   [E] unlock(report_lock:0)

context B
   [S] lock(&tb->tb6_lock:0)
   [W] lock(report_lock:0)
   [E] unlock(&tb->tb6_lock:0)

context C
   [S] write_lock(&ndev->lock:0)
   [W] lock(&tb->tb6_lock:0)
   [E] write_unlock(&ndev->lock:0)

context D
   [S] lock(&vn->busy.lock:0)
   [W] write_lock(&ndev->lock:0)
   [E] unlock(&vn->busy.lock:0)

[S]: start of the event context
[W]: the wait blocked
[E]: the event not reachable
---------------------------------------------------
context A's detail
---------------------------------------------------
context A
   [S] lock(report_lock:0)
   [W] lock(&vn->busy.lock:0)
   [E] unlock(report_lock:0)

[S] lock(report_lock:0):
[<ffff800080bd2600>] start_report mm/kasan/report.c:215 [inline]
[<ffff800080bd2600>] kasan_report+0x74/0x1d4 mm/kasan/report.c:623
stacktrace:
      __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
      _raw_spin_lock_irqsave+0x88/0xd8 kernel/locking/spinlock.c:162
      start_report mm/kasan/report.c:215 [inline]
      kasan_report+0x74/0x1d4 mm/kasan/report.c:623
      __asan_report_load4_noabort+0x20/0x2c mm/kasan/report_generic.c:380
      fib6_ifdown+0x67c/0x6bc net/ipv6/route.c:4910
      fib6_clean_node+0x23c/0x4e0 net/ipv6/ip6_fib.c:2199
      fib6_walk_continue+0x38c/0x774 net/ipv6/ip6_fib.c:2124
      fib6_walk+0x158/0x31c net/ipv6/ip6_fib.c:2172
      fib6_clean_tree+0xe0/0x128 net/ipv6/ip6_fib.c:2252
      __fib6_clean_all+0x104/0x2b8 net/ipv6/ip6_fib.c:2268
      fib6_clean_all+0x3c/0x50 net/ipv6/ip6_fib.c:2279
      rt6_sync_down_dev net/ipv6/route.c:4951 [inline]
      rt6_disable_ip+0x270/0x840 net/ipv6/route.c:4956
      addrconf_ifdown.isra.0+0x104/0x175c net/ipv6/addrconf.c:3857
      addrconf_notify+0x3a0/0x1688 net/ipv6/addrconf.c:3780
      notifier_call_chain+0x94/0x50c kernel/notifier.c:85
      raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453
      call_netdevice_notifiers_info+0xb8/0x150 net/core/dev.c:2176

[W] lock(&vn->busy.lock:0):
[<ffff800080ae57a0>] spin_lock include/linux/spinlock.h:351 [inline]
[<ffff800080ae57a0>] find_vmap_area+0xa0/0x228 mm/vmalloc.c:2418
stacktrace:
      spin_lock include/linux/spinlock.h:351 [inline]
      find_vmap_area+0xa0/0x228 mm/vmalloc.c:2418
      find_vm_area+0x20/0x68 mm/vmalloc.c:3208
      kasan_find_vm_area mm/kasan/report.c:398 [inline]
      print_address_description mm/kasan/report.c:432 [inline]
      print_report+0x3d8/0x54c mm/kasan/report.c:521
      kasan_report+0xb8/0x1d4 mm/kasan/report.c:634
      __asan_report_load4_noabort+0x20/0x2c mm/kasan/report_generic.c:380
      fib6_ifdown+0x67c/0x6bc net/ipv6/route.c:4910
      fib6_clean_node+0x23c/0x4e0 net/ipv6/ip6_fib.c:2199
      fib6_walk_continue+0x38c/0x774 net/ipv6/ip6_fib.c:2124
      fib6_walk+0x158/0x31c net/ipv6/ip6_fib.c:2172
      fib6_clean_tree+0xe0/0x128 net/ipv6/ip6_fib.c:2252
      __fib6_clean_all+0x104/0x2b8 net/ipv6/ip6_fib.c:2268
      fib6_clean_all+0x3c/0x50 net/ipv6/ip6_fib.c:2279
      rt6_sync_down_dev net/ipv6/route.c:4951 [inline]
      rt6_disable_ip+0x270/0x840 net/ipv6/route.c:4956
      addrconf_ifdown.isra.0+0x104/0x175c net/ipv6/addrconf.c:3857
      addrconf_notify+0x3a0/0x1688 net/ipv6/addrconf.c:3780
      notifier_call_chain+0x94/0x50c kernel/notifier.c:85

[E] unlock(report_lock:0):
(N/A)
---------------------------------------------------
context B's detail
---------------------------------------------------
context B
   [S] lock(&tb->tb6_lock:0)
   [W] lock(report_lock:0)
   [E] unlock(&tb->tb6_lock:0)

[S] lock(&tb->tb6_lock:0):
[<ffff80008a172d10>] spin_lock_bh include/linux/spinlock.h:356 [inline]
[<ffff80008a172d10>] __fib6_clean_all+0xe8/0x2b8 net/ipv6/ip6_fib.c:2267
stacktrace:
      __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
      _raw_spin_lock_bh+0x80/0xd0 kernel/locking/spinlock.c:178
      spin_lock_bh include/linux/spinlock.h:356 [inline]
      __fib6_clean_all+0xe8/0x2b8 net/ipv6/ip6_fib.c:2267
      fib6_clean_all+0x3c/0x50 net/ipv6/ip6_fib.c:2279
      rt6_sync_down_dev net/ipv6/route.c:4951 [inline]
      rt6_disable_ip+0x270/0x840 net/ipv6/route.c:4956
      addrconf_ifdown.isra.0+0x104/0x175c net/ipv6/addrconf.c:3857
      addrconf_notify+0x3a0/0x1688 net/ipv6/addrconf.c:3780
      notifier_call_chain+0x94/0x50c kernel/notifier.c:85
      raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453
      call_netdevice_notifiers_info+0xb8/0x150 net/core/dev.c:2176
      call_netdevice_notifiers_extack net/core/dev.c:2214 [inline]
      call_netdevice_notifiers net/core/dev.c:2228 [inline]
      dev_close_many+0x290/0x4b8 net/core/dev.c:1731
      unregister_netdevice_many_notify+0x574/0x1fa0 net/core/dev.c:11940
      unregister_netdevice_many net/core/dev.c:12034 [inline]
      unregister_netdevice_queue+0x2b8/0x390 net/core/dev.c:11877
      unregister_netdevice include/linux/netdevice.h:3374 [inline]
      __tun_detach+0xec4/0x1180 drivers/net/tun.c:620
      tun_detach drivers/net/tun.c:636 [inline]
      tun_chr_close+0xa4/0x248 drivers/net/tun.c:3390
      __fput+0x374/0xa30 fs/file_table.c:465
      ____fput+0x20/0x3c fs/file_table.c:493

[W] lock(report_lock:0):
[<ffff800080bd2600>] start_report mm/kasan/report.c:215 [inline]
[<ffff800080bd2600>] kasan_report+0x74/0x1d4 mm/kasan/report.c:623
stacktrace:
      __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
      _raw_spin_lock_irqsave+0x6c/0xd8 kernel/locking/spinlock.c:162
      start_report mm/kasan/report.c:215 [inline]
      kasan_report+0x74/0x1d4 mm/kasan/report.c:623
      __asan_report_load4_noabort+0x20/0x2c mm/kasan/report_generic.c:380
      fib6_ifdown+0x67c/0x6bc net/ipv6/route.c:4910
      fib6_clean_node+0x23c/0x4e0 net/ipv6/ip6_fib.c:2199
      fib6_walk_continue+0x38c/0x774 net/ipv6/ip6_fib.c:2124
      fib6_walk+0x158/0x31c net/ipv6/ip6_fib.c:2172
      fib6_clean_tree+0xe0/0x128 net/ipv6/ip6_fib.c:2252
      __fib6_clean_all+0x104/0x2b8 net/ipv6/ip6_fib.c:2268
      fib6_clean_all+0x3c/0x50 net/ipv6/ip6_fib.c:2279
      rt6_sync_down_dev net/ipv6/route.c:4951 [inline]
      rt6_disable_ip+0x270/0x840 net/ipv6/route.c:4956
      addrconf_ifdown.isra.0+0x104/0x175c net/ipv6/addrconf.c:3857
      addrconf_notify+0x3a0/0x1688 net/ipv6/addrconf.c:3780
      notifier_call_chain+0x94/0x50c kernel/notifier.c:85
      raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453
      call_netdevice_notifiers_info+0xb8/0x150 net/core/dev.c:2176

[E] unlock(&tb->tb6_lock:0):
(N/A)
---------------------------------------------------
context C's detail
---------------------------------------------------
context C
   [S] write_lock(&ndev->lock:0)
   [W] lock(&tb->tb6_lock:0)
   [E] write_unlock(&ndev->lock:0)

[S] write_lock(&ndev->lock:0):
[<ffff80008a133bd8>] addrconf_permanent_addr net/ipv6/addrconf.c:3622 [inline]
[<ffff80008a133bd8>] addrconf_notify+0xab4/0x1688 net/ipv6/addrconf.c:3698
stacktrace:
      __raw_write_lock_bh include/linux/rwlock_api_smp.h:202 [inline]
      _raw_write_lock_bh+0x88/0xd4 kernel/locking/spinlock.c:334
      addrconf_permanent_addr net/ipv6/addrconf.c:3622 [inline]
      addrconf_notify+0xab4/0x1688 net/ipv6/addrconf.c:3698
      notifier_call_chain+0x94/0x50c kernel/notifier.c:85
      raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453
      call_netdevice_notifiers_info+0xb8/0x150 net/core/dev.c:2176
      call_netdevice_notifiers_extack net/core/dev.c:2214 [inline]
      call_netdevice_notifiers net/core/dev.c:2228 [inline]
      __dev_notify_flags+0x114/0x294 net/core/dev.c:9393
      netif_change_flags+0x108/0x160 net/core/dev.c:9422
      do_setlink.isra.0+0x960/0x3464 net/core/rtnetlink.c:3152
      rtnl_changelink net/core/rtnetlink.c:3769 [inline]
      __rtnl_newlink net/core/rtnetlink.c:3928 [inline]
      rtnl_newlink+0x1080/0x1a1c net/core/rtnetlink.c:4065
      rtnetlink_rcv_msg+0x82c/0xc30 net/core/rtnetlink.c:6955
      netlink_rcv_skb+0x218/0x400 net/netlink/af_netlink.c:2534
      rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6982
      netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
      netlink_unicast+0x50c/0x778 net/netlink/af_netlink.c:1339
      netlink_sendmsg+0x794/0xc28 net/netlink/af_netlink.c:1883
      sock_sendmsg_nosec net/socket.c:712 [inline]
      __sock_sendmsg+0xe0/0x1a0 net/socket.c:727
      __sys_sendto+0x238/0x2fc net/socket.c:2180

[W] lock(&tb->tb6_lock:0):
[<ffff80008a1643fc>] spin_lock_bh include/linux/spinlock.h:356 [inline]
[<ffff80008a1643fc>] __ip6_ins_rt net/ipv6/route.c:1350 [inline]
[<ffff80008a1643fc>] ip6_route_add+0x7c/0x220 net/ipv6/route.c:3900
stacktrace:
      __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
      _raw_spin_lock_bh+0x5c/0xd0 kernel/locking/spinlock.c:178
      spin_lock_bh include/linux/spinlock.h:356 [inline]
      __ip6_ins_rt net/ipv6/route.c:1350 [inline]
      ip6_route_add+0x7c/0x220 net/ipv6/route.c:3900
      addrconf_prefix_route+0x28c/0x494 net/ipv6/addrconf.c:2487
      fixup_permanent_addr net/ipv6/addrconf.c:3602 [inline]
      addrconf_permanent_addr net/ipv6/addrconf.c:3626 [inline]
      addrconf_notify+0xfd0/0x1688 net/ipv6/addrconf.c:3698
      notifier_call_chain+0x94/0x50c kernel/notifier.c:85
      raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453
      call_netdevice_notifiers_info+0xb8/0x150 net/core/dev.c:2176
      call_netdevice_notifiers_extack net/core/dev.c:2214 [inline]
      call_netdevice_notifiers net/core/dev.c:2228 [inline]
      __dev_notify_flags+0x114/0x294 net/core/dev.c:9393
      netif_change_flags+0x108/0x160 net/core/dev.c:9422
      do_setlink.isra.0+0x960/0x3464 net/core/rtnetlink.c:3152
      rtnl_changelink net/core/rtnetlink.c:3769 [inline]
      __rtnl_newlink net/core/rtnetlink.c:3928 [inline]
      rtnl_newlink+0x1080/0x1a1c net/core/rtnetlink.c:4065
      rtnetlink_rcv_msg+0x82c/0xc30 net/core/rtnetlink.c:6955
      netlink_rcv_skb+0x218/0x400 net/netlink/af_netlink.c:2534
      rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6982
      netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
      netlink_unicast+0x50c/0x778 net/netlink/af_netlink.c:1339
      netlink_sendmsg+0x794/0xc28 net/netlink/af_netlink.c:1883

[E] write_unlock(&ndev->lock:0):
(N/A)
---------------------------------------------------
context D's detail
---------------------------------------------------
context D
   [S] lock(&vn->busy.lock:0)
   [W] write_lock(&ndev->lock:0)
   [E] unlock(&vn->busy.lock:0)

[S] lock(&vn->busy.lock:0):
[<ffff800080adcf80>] spin_lock include/linux/spinlock.h:351 [inline]
[<ffff800080adcf80>] alloc_vmap_area+0x800/0x26d0 mm/vmalloc.c:2027
stacktrace:
      __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
      _raw_spin_lock+0x78/0xc0 kernel/locking/spinlock.c:154
      spin_lock include/linux/spinlock.h:351 [inline]
      alloc_vmap_area+0x800/0x26d0 mm/vmalloc.c:2027
      __get_vm_area_node+0x1c8/0x360 mm/vmalloc.c:3138
      __vmalloc_node_range_noprof+0x168/0x10d4 mm/vmalloc.c:3805
      __vmalloc_node_noprof+0x130/0x178 mm/vmalloc.c:3908
      vzalloc_noprof+0x3c/0x54 mm/vmalloc.c:3981
      alloc_counters net/ipv6/netfilter/ip6_tables.c:815 [inline]
      copy_entries_to_user net/ipv6/netfilter/ip6_tables.c:837 [inline]
      get_entries net/ipv6/netfilter/ip6_tables.c:1039 [inline]
      do_ip6t_get_ctl+0x520/0xad0 net/ipv6/netfilter/ip6_tables.c:1677
      nf_getsockopt+0x8c/0x10c net/netfilter/nf_sockopt.c:116
      ipv6_getsockopt+0x24c/0x460 net/ipv6/ipv6_sockglue.c:1493
      tcp_getsockopt+0x98/0x120 net/ipv4/tcp.c:4727
      sock_common_getsockopt+0x9c/0xcc net/core/sock.c:3867
      do_sock_getsockopt+0x308/0x57c net/socket.c:2357
      __sys_getsockopt+0xec/0x188 net/socket.c:2386
      __do_sys_getsockopt net/socket.c:2393 [inline]
      __se_sys_getsockopt net/socket.c:2390 [inline]
      __arm64_sys_getsockopt+0xa8/0x110 net/socket.c:2390
      __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline]
      invoke_syscall+0x88/0x2e0 arch/arm64/kernel/syscall.c:50
      el0_svc_common.constprop.0+0xe8/0x2e0 arch/arm64/kernel/syscall.c:139

[W] write_lock(&ndev->lock:0):
[<ffff80008a127f20>] addrconf_rs_timer+0xa0/0x730 net/ipv6/addrconf.c:4025
stacktrace:
      __raw_write_lock include/linux/rwlock_api_smp.h:209 [inline]
      _raw_write_lock+0x5c/0xd0 kernel/locking/spinlock.c:300
      addrconf_rs_timer+0xa0/0x730 net/ipv6/addrconf.c:4025
      call_timer_fn+0x204/0x964 kernel/time/timer.c:1789
      expire_timers kernel/time/timer.c:1840 [inline]
      __run_timers+0x830/0xb00 kernel/time/timer.c:2414
      __run_timer_base kernel/time/timer.c:2426 [inline]
      __run_timer_base kernel/time/timer.c:2418 [inline]
      run_timer_base+0x124/0x198 kernel/time/timer.c:2435
      run_timer_softirq+0x20/0x58 kernel/time/timer.c:2445
      handle_softirqs+0x30c/0xdc0 kernel/softirq.c:579
      __do_softirq+0x14/0x20 kernel/softirq.c:613
      ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:81
      call_on_irq_stack+0x24/0x30 arch/arm64/kernel/entry.S:891
      do_softirq_own_stack+0x20/0x40 arch/arm64/kernel/irq.c:86
      invoke_softirq kernel/softirq.c:460 [inline]
      __irq_exit_rcu+0x400/0x560 kernel/softirq.c:680
      irq_exit_rcu+0x14/0x80 kernel/softirq.c:696
      __el1_irq arch/arm64/kernel/entry-common.c:561 [inline]
      el1_interrupt+0x38/0x54 arch/arm64/kernel/entry-common.c:575
      el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:580
      el1h_64_irq+0x6c/0x70 arch/arm64/kernel/entry.S:596

[E] unlock(&vn->busy.lock:0):
(N/A)
---------------------------------------------------
information that might be helpful
---------------------------------------------------
CPU: 1 UID: 0 PID: 19536 Comm: syz.4.2592 Not tainted 6.15.0-rc6-00043-ga83a69ec7f9f #5 PREEMPT
Hardware name: QEMU KVM Virtual Machine, BIOS 2025.02-8 05/13/2025
Call trace:
 dump_backtrace arch/arm64/kernel/stacktrace.c:449 [inline] (C)
 show_stack+0x34/0x80 arch/arm64/kernel/stacktrace.c:466 (C)
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x104/0x180 lib/dump_stack.c:120
 dump_stack+0x20/0x2c lib/dump_stack.c:129
 print_circle kernel/dependency/dept.c:928 [inline]
 cb_check_dl kernel/dependency/dept.c:1362 [inline]
 cb_check_dl+0x1080/0x10ec kernel/dependency/dept.c:1356
 bfs+0x4d8/0x630 kernel/dependency/dept.c:980
 check_dl_bfs kernel/dependency/dept.c:1381 [inline]
 add_dep+0x1cc/0x364 kernel/dependency/dept.c:1710
 add_wait kernel/dependency/dept.c:1829 [inline]
 __dept_wait+0x60c/0x16e0 kernel/dependency/dept.c:2585
 dept_wait kernel/dependency/dept.c:2666 [inline]
 dept_wait+0x168/0x1a8 kernel/dependency/dept.c:2640
 __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
 _raw_spin_lock+0x54/0xc0 kernel/locking/spinlock.c:154
 spin_lock include/linux/spinlock.h:351 [inline]
 find_vmap_area+0xa0/0x228 mm/vmalloc.c:2418
 find_vm_area+0x20/0x68 mm/vmalloc.c:3208
 kasan_find_vm_area mm/kasan/report.c:398 [inline]
 print_address_description mm/kasan/report.c:432 [inline]
 print_report+0x3d8/0x54c mm/kasan/report.c:521
 kasan_report+0xb8/0x1d4 mm/kasan/report.c:634
 __asan_report_load4_noabort+0x20/0x2c mm/kasan/report_generic.c:380
 fib6_ifdown+0x67c/0x6bc net/ipv6/route.c:4910
 fib6_clean_node+0x23c/0x4e0 net/ipv6/ip6_fib.c:2199
 fib6_walk_continue+0x38c/0x774 net/ipv6/ip6_fib.c:2124
 fib6_walk+0x158/0x31c net/ipv6/ip6_fib.c:2172
 fib6_clean_tree+0xe0/0x128 net/ipv6/ip6_fib.c:2252
 __fib6_clean_all+0x104/0x2b8 net/ipv6/ip6_fib.c:2268
 fib6_clean_all+0x3c/0x50 net/ipv6/ip6_fib.c:2279
 rt6_sync_down_dev net/ipv6/route.c:4951 [inline]
 rt6_disable_ip+0x270/0x840 net/ipv6/route.c:4956
 addrconf_ifdown.isra.0+0x104/0x175c net/ipv6/addrconf.c:3857
 addrconf_notify+0x3a0/0x1688 net/ipv6/addrconf.c:3780
 notifier_call_chain+0x94/0x50c kernel/notifier.c:85
 raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453
 call_netdevice_notifiers_info+0xb8/0x150 net/core/dev.c:2176
 call_netdevice_notifiers_extack net/core/dev.c:2214 [inline]
 call_netdevice_notifiers net/core/dev.c:2228 [inline]
 dev_close_many+0x290/0x4b8 net/core/dev.c:1731
 unregister_netdevice_many_notify+0x574/0x1fa0 net/core/dev.c:11940
 unregister_netdevice_many net/core/dev.c:12034 [inline]
 unregister_netdevice_queue+0x2b8/0x390 net/core/dev.c:11877
 unregister_netdevice include/linux/netdevice.h:3374 [inline]
 __tun_detach+0xec4/0x1180 drivers/net/tun.c:620
 tun_detach drivers/net/tun.c:636 [inline]
 tun_chr_close+0xa4/0x248 drivers/net/tun.c:3390
 __fput+0x374/0xa30 fs/file_table.c:465
 ____fput+0x20/0x3c fs/file_table.c:493
 task_work_run+0x154/0x278 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0x950/0x23a8 kernel/exit.c:953
 do_group_exit+0xc0/0x248 kernel/exit.c:1103
 get_signal+0x1f98/0x20cc kernel/signal.c:3034
 do_signal+0x200/0x880 arch/arm64/kernel/signal.c:1658
 do_notify_resume+0x1a0/0x26c arch/arm64/kernel/entry-common.c:148
 exit_to_user_mode_prepare arch/arm64/kernel/entry-common.c:169 [inline]
 exit_to_user_mode arch/arm64/kernel/entry-common.c:178 [inline]
 el0_svc+0xf8/0x188 arch/arm64/kernel/entry-common.c:745
 el0t_64_sync_handler+0x10c/0x140 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600

---
 mm/kasan/report.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/kasan/report.c b/mm/kasan/report.c
index 8357e1a33699..61c590e8005e 100644
--- a/mm/kasan/report.c
+++ b/mm/kasan/report.c
@@ -387,7 +387,7 @@ static inline struct vm_struct *kasan_find_vm_area(void *addr)
 	static DEFINE_WAIT_OVERRIDE_MAP(vmalloc_map, LD_WAIT_SLEEP);
 	struct vm_struct *va;

-	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+	if (IS_ENABLED(CONFIG_PREEMPT_RT) || in_interrupt())
 		return NULL;

 	/*
--
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}

On 2025-07-01 21:35:45 [+0100], Yeoreum Yun wrote:
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index 8357e1a33699..61c590e8005e 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -387,7 +387,7 @@ static inline struct vm_struct *kasan_find_vm_area(void *addr)
>  	static DEFINE_WAIT_OVERRIDE_MAP(vmalloc_map, LD_WAIT_SLEEP);
>  	struct vm_struct *va;
> 
> -	if (IS_ENABLED(CONFIG_PREEMPT_RT))
> +	if (IS_ENABLED(CONFIG_PREEMPT_RT) || in_interrupt())

Could we stick to irq_count() ?

>  		return NULL;
> 
>  	/*

Sebastian

Hi Sebastian,

> On 2025-07-01 21:35:45 [+0100], Yeoreum Yun wrote:
> > diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> > index 8357e1a33699..61c590e8005e 100644
> > --- a/mm/kasan/report.c
> > +++ b/mm/kasan/report.c
> > @@ -387,7 +387,7 @@ static inline struct vm_struct *kasan_find_vm_area(void *addr)
> >  	static DEFINE_WAIT_OVERRIDE_MAP(vmalloc_map, LD_WAIT_SLEEP);
> >  	struct vm_struct *va;
> >
> > -	if (IS_ENABLED(CONFIG_PREEMPT_RT))
> > +	if (IS_ENABLED(CONFIG_PREEMPT_RT) || in_interrupt())
>
> Could we stick to irq_count() ?

I determine to remove kasan_find_vm_area() since there's some case
couldn't be avoid with irq_count()

Please see the latest discussion:
 https://lore.kernel.org/all/20250703181018.580833-1-yeoreum.yun@arm.com/

Thanks ;)

--
Sincerely,
Yeoreum Yun

On 7/1/25 10:35 PM, Yeoreum Yun wrote:

FYI some of email addresses in CC look corrupted, e.g. "kpm@linux-foundation.org", "nd@arm.com"

> In below senario, kasan causes deadlock while reporting vm area informaion:
> 
> CPU0                                CPU1
> vmalloc();
>  alloc_vmap_area();
>   spin_lock(&vn->busy.lock)
>                                     spin_lock_bh(&some_lock);
>    <interrupt occurs>
>    <in softirq>
>    spin_lock(&some_lock);
>                                     <access invalid address>
>                                     kasan_report();
>                                      print_report();
>                                       print_address_description();
>                                        kasan_find_vm_area();
>                                         find_vm_area();
>                                          spin_lock(&vn->busy.lock) // deadlock!
> 
...

> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index 8357e1a33699..61c590e8005e 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -387,7 +387,7 @@ static inline struct vm_struct *kasan_find_vm_area(void *addr)
>  	static DEFINE_WAIT_OVERRIDE_MAP(vmalloc_map, LD_WAIT_SLEEP);
>  	struct vm_struct *va;
> 
> -	if (IS_ENABLED(CONFIG_PREEMPT_RT))
> +	if (IS_ENABLED(CONFIG_PREEMPT_RT) || in_interrupt())

in_interrupt() returns true if BH disabled, so this indeed should avoid the deadlock.
However, it seems we have similar problem with 'spin_lock_irq[save](&some_lock)' case and
in_interrupt() check doesn't fix it.

And adding irqs_disabled() check wouldn't make sense because print_report() always
 runs with irqs disabled.

I see no obvious way to fix this rather than remove find_vm_area() call completely and just
print less info.

Hi Andrey,

>
> FYI some of email addresses in CC look corrupted, e.g. "kpm@linux-foundation.org", "nd@arm.com"

Sorry and Thanks to let me know :)

>
> > In below senario, kasan causes deadlock while reporting vm area informaion:
> >
> > CPU0                                CPU1
> > vmalloc();
> >  alloc_vmap_area();
> >   spin_lock(&vn->busy.lock)
> >                                     spin_lock_bh(&some_lock);
> >    <interrupt occurs>
> >    <in softirq>
> >    spin_lock(&some_lock);
> >                                     <access invalid address>
> >                                     kasan_report();
> >                                      print_report();
> >                                       print_address_description();
> >                                        kasan_find_vm_area();
> >                                         find_vm_area();
> >                                          spin_lock(&vn->busy.lock) // deadlock!
> >
> ...
>
> > diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> > index 8357e1a33699..61c590e8005e 100644
> > --- a/mm/kasan/report.c
> > +++ b/mm/kasan/report.c
> > @@ -387,7 +387,7 @@ static inline struct vm_struct *kasan_find_vm_area(void *addr)
> >  	static DEFINE_WAIT_OVERRIDE_MAP(vmalloc_map, LD_WAIT_SLEEP);
> >  	struct vm_struct *va;
> >
> > -	if (IS_ENABLED(CONFIG_PREEMPT_RT))
> > +	if (IS_ENABLED(CONFIG_PREEMPT_RT) || in_interrupt())
>
> in_interrupt() returns true if BH disabled, so this indeed should avoid the deadlock.
> However, it seems we have similar problem with 'spin_lock_irq[save](&some_lock)' case and
> in_interrupt() check doesn't fix it.
> And adding irqs_disabled() check wouldn't make sense because print_report() always
>  runs with irqs disabled.
> I see no obvious way to fix this rather than remove find_vm_area() call completely and just
> print less info.

Right. unless there is API -- find_vm_area() with spin_trylock(),
kasan_find_vm_area() should be removed.

But, I'm not sure adding the new API used only bv kasan is better then
just remove kasan_find_vm_area().

Do you have any idea for this?

Thanks.

--
Sincerely,
Yeoreum Yun

On 7/2/25 6:04 PM, Yeoreum Yun wrote:
> Hi Andrey,
> 
>>
>> FYI some of email addresses in CC look corrupted, e.g. "kpm@linux-foundation.org", "nd@arm.com"
> 
> Sorry and Thanks to let me know :)
> 
>>
>>> In below senario, kasan causes deadlock while reporting vm area informaion:
>>>
>>> CPU0                                CPU1
>>> vmalloc();
>>>  alloc_vmap_area();
>>>   spin_lock(&vn->busy.lock)
>>>                                     spin_lock_bh(&some_lock);
>>>    <interrupt occurs>
>>>    <in softirq>
>>>    spin_lock(&some_lock);
>>>                                     <access invalid address>
>>>                                     kasan_report();
>>>                                      print_report();
>>>                                       print_address_description();
>>>                                        kasan_find_vm_area();
>>>                                         find_vm_area();
>>>                                          spin_lock(&vn->busy.lock) // deadlock!
>>>
>> ...
>>
>>> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
>>> index 8357e1a33699..61c590e8005e 100644
>>> --- a/mm/kasan/report.c
>>> +++ b/mm/kasan/report.c
>>> @@ -387,7 +387,7 @@ static inline struct vm_struct *kasan_find_vm_area(void *addr)
>>>  	static DEFINE_WAIT_OVERRIDE_MAP(vmalloc_map, LD_WAIT_SLEEP);
>>>  	struct vm_struct *va;
>>>
>>> -	if (IS_ENABLED(CONFIG_PREEMPT_RT))
>>> +	if (IS_ENABLED(CONFIG_PREEMPT_RT) || in_interrupt())
>>
>> in_interrupt() returns true if BH disabled, so this indeed should avoid the deadlock.
>> However, it seems we have similar problem with 'spin_lock_irq[save](&some_lock)' case and
>> in_interrupt() check doesn't fix it.
>> And adding irqs_disabled() check wouldn't make sense because print_report() always
>>  runs with irqs disabled.
>> I see no obvious way to fix this rather than remove find_vm_area() call completely and just
>> print less info.
> 
> Right. unless there is API -- find_vm_area() with spin_trylock(),
> kasan_find_vm_area() should be removed.
> 
> But, I'm not sure adding the new API used only bv kasan is better then
> just remove kasan_find_vm_area().
> 
> Do you have any idea for this?
> 

I'd say the info from vm_struct is nice to have, but it's not essential for debugging.
It's probably not worth trying to keep it, so I'd vote for for removing kasan_find_vm_area().


> Thanks.
> 
> --
> Sincerely,
> Yeoreum Yun

Hi Andrey,

> [...]
> > Right. unless there is API -- find_vm_area() with spin_trylock(),
> > kasan_find_vm_area() should be removed.
> >
> > But, I'm not sure adding the new API used only bv kasan is better then
> > just remove kasan_find_vm_area().
> >
> > Do you have any idea for this?
> >
>
> I'd say the info from vm_struct is nice to have, but it's not essential for debugging.
> It's probably not worth trying to keep it, so I'd vote for for removing kasan_find_vm_area().

Thanks for sharing. I'll respin with it.

--
Sincerely,
Yeoreum Yun

On Tue, Jul 01, 2025 at 09:35:45PM +0100, Yeoreum Yun wrote:
> 
> 
> Caution: External Email. Please take care when clicking links or opening attachments.
> 
> 
> 
> 
> 
> 
> In below senario, kasan causes deadlock while reporting vm area informaion:
> 
> CPU0                                CPU1
> vmalloc();
>  alloc_vmap_area();
>   spin_lock(&vn->busy.lock)
			^
	Here, it should be spin_lock_bh(&vn->busy.lock).

>                                     spin_lock_bh(&some_lock);
>    <interrupt occurs>
>    <in softirq>
>    spin_lock(&some_lock);
>                                     <access invalid address>
>                                     kasan_report();
>                                      print_report();
>                                       print_address_description();
>                                        kasan_find_vm_area();
>                                         find_vm_area();
>                                          spin_lock(&vn->busy.lock) // deadlock!
						^
		It should be spin_lock_bh(&vn->busy.lock), since it can
		be within a critical section of *spin_lock_bh*() to
		avoid a deadlock with softirq involved.

	Byungchul

> To resolve this possible deadlock, don't call find_vm_area()
> to prevent possible deadlock while kasan reports vm area information.
> 
> Fixes: c056a364e954 ("kasan: print virtual mapping info in reports")
> Reported-by: Yunseong Kim <ysk@kzalloc.com>
> Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
> ---
> Below report is from Yunseong Kim using DEPT:
> 
> ===================================================
> DEPT: Circular dependency has been detected.
> 6.15.0-rc6-00043-ga83a69ec7f9f #5 Not tainted
> ---------------------------------------------------
> summary
> ---------------------------------------------------
> *** DEADLOCK ***
> 
> context A
>    [S] lock(report_lock:0)
>    [W] lock(&vn->busy.lock:0)
>    [E] unlock(report_lock:0)
> 
> context B
>    [S] lock(&tb->tb6_lock:0)
>    [W] lock(report_lock:0)
>    [E] unlock(&tb->tb6_lock:0)
> 
> context C
>    [S] write_lock(&ndev->lock:0)
>    [W] lock(&tb->tb6_lock:0)
>    [E] write_unlock(&ndev->lock:0)
> 
> context D
>    [S] lock(&vn->busy.lock:0)
>    [W] write_lock(&ndev->lock:0)
>    [E] unlock(&vn->busy.lock:0)
> 
> [S]: start of the event context
> [W]: the wait blocked
> [E]: the event not reachable
> ---------------------------------------------------
> context A's detail
> ---------------------------------------------------
> context A
>    [S] lock(report_lock:0)
>    [W] lock(&vn->busy.lock:0)
>    [E] unlock(report_lock:0)
> 
> [S] lock(report_lock:0):
> [<ffff800080bd2600>] start_report mm/kasan/report.c:215 [inline]
> [<ffff800080bd2600>] kasan_report+0x74/0x1d4 mm/kasan/report.c:623
> stacktrace:
>       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
>       _raw_spin_lock_irqsave+0x88/0xd8 kernel/locking/spinlock.c:162
>       start_report mm/kasan/report.c:215 [inline]
>       kasan_report+0x74/0x1d4 mm/kasan/report.c:623
>       __asan_report_load4_noabort+0x20/0x2c mm/kasan/report_generic.c:380
>       fib6_ifdown+0x67c/0x6bc net/ipv6/route.c:4910
>       fib6_clean_node+0x23c/0x4e0 net/ipv6/ip6_fib.c:2199
>       fib6_walk_continue+0x38c/0x774 net/ipv6/ip6_fib.c:2124
>       fib6_walk+0x158/0x31c net/ipv6/ip6_fib.c:2172
>       fib6_clean_tree+0xe0/0x128 net/ipv6/ip6_fib.c:2252
>       __fib6_clean_all+0x104/0x2b8 net/ipv6/ip6_fib.c:2268
>       fib6_clean_all+0x3c/0x50 net/ipv6/ip6_fib.c:2279
>       rt6_sync_down_dev net/ipv6/route.c:4951 [inline]
>       rt6_disable_ip+0x270/0x840 net/ipv6/route.c:4956
>       addrconf_ifdown.isra.0+0x104/0x175c net/ipv6/addrconf.c:3857
>       addrconf_notify+0x3a0/0x1688 net/ipv6/addrconf.c:3780
>       notifier_call_chain+0x94/0x50c kernel/notifier.c:85
>       raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453
>       call_netdevice_notifiers_info+0xb8/0x150 net/core/dev.c:2176
> 
> [W] lock(&vn->busy.lock:0):
> [<ffff800080ae57a0>] spin_lock include/linux/spinlock.h:351 [inline]
> [<ffff800080ae57a0>] find_vmap_area+0xa0/0x228 mm/vmalloc.c:2418
> stacktrace:
>       spin_lock include/linux/spinlock.h:351 [inline]
>       find_vmap_area+0xa0/0x228 mm/vmalloc.c:2418
>       find_vm_area+0x20/0x68 mm/vmalloc.c:3208
>       kasan_find_vm_area mm/kasan/report.c:398 [inline]
>       print_address_description mm/kasan/report.c:432 [inline]
>       print_report+0x3d8/0x54c mm/kasan/report.c:521
>       kasan_report+0xb8/0x1d4 mm/kasan/report.c:634
>       __asan_report_load4_noabort+0x20/0x2c mm/kasan/report_generic.c:380
>       fib6_ifdown+0x67c/0x6bc net/ipv6/route.c:4910
>       fib6_clean_node+0x23c/0x4e0 net/ipv6/ip6_fib.c:2199
>       fib6_walk_continue+0x38c/0x774 net/ipv6/ip6_fib.c:2124
>       fib6_walk+0x158/0x31c net/ipv6/ip6_fib.c:2172
>       fib6_clean_tree+0xe0/0x128 net/ipv6/ip6_fib.c:2252
>       __fib6_clean_all+0x104/0x2b8 net/ipv6/ip6_fib.c:2268
>       fib6_clean_all+0x3c/0x50 net/ipv6/ip6_fib.c:2279
>       rt6_sync_down_dev net/ipv6/route.c:4951 [inline]
>       rt6_disable_ip+0x270/0x840 net/ipv6/route.c:4956
>       addrconf_ifdown.isra.0+0x104/0x175c net/ipv6/addrconf.c:3857
>       addrconf_notify+0x3a0/0x1688 net/ipv6/addrconf.c:3780
>       notifier_call_chain+0x94/0x50c kernel/notifier.c:85
> 
> [E] unlock(report_lock:0):
> (N/A)
> ---------------------------------------------------
> context B's detail
> ---------------------------------------------------
> context B
>    [S] lock(&tb->tb6_lock:0)
>    [W] lock(report_lock:0)
>    [E] unlock(&tb->tb6_lock:0)
> 
> [S] lock(&tb->tb6_lock:0):
> [<ffff80008a172d10>] spin_lock_bh include/linux/spinlock.h:356 [inline]
> [<ffff80008a172d10>] __fib6_clean_all+0xe8/0x2b8 net/ipv6/ip6_fib.c:2267
> stacktrace:
>       __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
>       _raw_spin_lock_bh+0x80/0xd0 kernel/locking/spinlock.c:178
>       spin_lock_bh include/linux/spinlock.h:356 [inline]
>       __fib6_clean_all+0xe8/0x2b8 net/ipv6/ip6_fib.c:2267
>       fib6_clean_all+0x3c/0x50 net/ipv6/ip6_fib.c:2279
>       rt6_sync_down_dev net/ipv6/route.c:4951 [inline]
>       rt6_disable_ip+0x270/0x840 net/ipv6/route.c:4956
>       addrconf_ifdown.isra.0+0x104/0x175c net/ipv6/addrconf.c:3857
>       addrconf_notify+0x3a0/0x1688 net/ipv6/addrconf.c:3780
>       notifier_call_chain+0x94/0x50c kernel/notifier.c:85
>       raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453
>       call_netdevice_notifiers_info+0xb8/0x150 net/core/dev.c:2176
>       call_netdevice_notifiers_extack net/core/dev.c:2214 [inline]
>       call_netdevice_notifiers net/core/dev.c:2228 [inline]
>       dev_close_many+0x290/0x4b8 net/core/dev.c:1731
>       unregister_netdevice_many_notify+0x574/0x1fa0 net/core/dev.c:11940
>       unregister_netdevice_many net/core/dev.c:12034 [inline]
>       unregister_netdevice_queue+0x2b8/0x390 net/core/dev.c:11877
>       unregister_netdevice include/linux/netdevice.h:3374 [inline]
>       __tun_detach+0xec4/0x1180 drivers/net/tun.c:620
>       tun_detach drivers/net/tun.c:636 [inline]
>       tun_chr_close+0xa4/0x248 drivers/net/tun.c:3390
>       __fput+0x374/0xa30 fs/file_table.c:465
>       ____fput+0x20/0x3c fs/file_table.c:493
> 
> [W] lock(report_lock:0):
> [<ffff800080bd2600>] start_report mm/kasan/report.c:215 [inline]
> [<ffff800080bd2600>] kasan_report+0x74/0x1d4 mm/kasan/report.c:623
> stacktrace:
>       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
>       _raw_spin_lock_irqsave+0x6c/0xd8 kernel/locking/spinlock.c:162
>       start_report mm/kasan/report.c:215 [inline]
>       kasan_report+0x74/0x1d4 mm/kasan/report.c:623
>       __asan_report_load4_noabort+0x20/0x2c mm/kasan/report_generic.c:380
>       fib6_ifdown+0x67c/0x6bc net/ipv6/route.c:4910
>       fib6_clean_node+0x23c/0x4e0 net/ipv6/ip6_fib.c:2199
>       fib6_walk_continue+0x38c/0x774 net/ipv6/ip6_fib.c:2124
>       fib6_walk+0x158/0x31c net/ipv6/ip6_fib.c:2172
>       fib6_clean_tree+0xe0/0x128 net/ipv6/ip6_fib.c:2252
>       __fib6_clean_all+0x104/0x2b8 net/ipv6/ip6_fib.c:2268
>       fib6_clean_all+0x3c/0x50 net/ipv6/ip6_fib.c:2279
>       rt6_sync_down_dev net/ipv6/route.c:4951 [inline]
>       rt6_disable_ip+0x270/0x840 net/ipv6/route.c:4956
>       addrconf_ifdown.isra.0+0x104/0x175c net/ipv6/addrconf.c:3857
>       addrconf_notify+0x3a0/0x1688 net/ipv6/addrconf.c:3780
>       notifier_call_chain+0x94/0x50c kernel/notifier.c:85
>       raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453
>       call_netdevice_notifiers_info+0xb8/0x150 net/core/dev.c:2176
> 
> [E] unlock(&tb->tb6_lock:0):
> (N/A)
> ---------------------------------------------------
> context C's detail
> ---------------------------------------------------
> context C
>    [S] write_lock(&ndev->lock:0)
>    [W] lock(&tb->tb6_lock:0)
>    [E] write_unlock(&ndev->lock:0)
> 
> [S] write_lock(&ndev->lock:0):
> [<ffff80008a133bd8>] addrconf_permanent_addr net/ipv6/addrconf.c:3622 [inline]
> [<ffff80008a133bd8>] addrconf_notify+0xab4/0x1688 net/ipv6/addrconf.c:3698
> stacktrace:
>       __raw_write_lock_bh include/linux/rwlock_api_smp.h:202 [inline]
>       _raw_write_lock_bh+0x88/0xd4 kernel/locking/spinlock.c:334
>       addrconf_permanent_addr net/ipv6/addrconf.c:3622 [inline]
>       addrconf_notify+0xab4/0x1688 net/ipv6/addrconf.c:3698
>       notifier_call_chain+0x94/0x50c kernel/notifier.c:85
>       raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453
>       call_netdevice_notifiers_info+0xb8/0x150 net/core/dev.c:2176
>       call_netdevice_notifiers_extack net/core/dev.c:2214 [inline]
>       call_netdevice_notifiers net/core/dev.c:2228 [inline]
>       __dev_notify_flags+0x114/0x294 net/core/dev.c:9393
>       netif_change_flags+0x108/0x160 net/core/dev.c:9422
>       do_setlink.isra.0+0x960/0x3464 net/core/rtnetlink.c:3152
>       rtnl_changelink net/core/rtnetlink.c:3769 [inline]
>       __rtnl_newlink net/core/rtnetlink.c:3928 [inline]
>       rtnl_newlink+0x1080/0x1a1c net/core/rtnetlink.c:4065
>       rtnetlink_rcv_msg+0x82c/0xc30 net/core/rtnetlink.c:6955
>       netlink_rcv_skb+0x218/0x400 net/netlink/af_netlink.c:2534
>       rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6982
>       netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
>       netlink_unicast+0x50c/0x778 net/netlink/af_netlink.c:1339
>       netlink_sendmsg+0x794/0xc28 net/netlink/af_netlink.c:1883
>       sock_sendmsg_nosec net/socket.c:712 [inline]
>       __sock_sendmsg+0xe0/0x1a0 net/socket.c:727
>       __sys_sendto+0x238/0x2fc net/socket.c:2180
> 
> [W] lock(&tb->tb6_lock:0):
> [<ffff80008a1643fc>] spin_lock_bh include/linux/spinlock.h:356 [inline]
> [<ffff80008a1643fc>] __ip6_ins_rt net/ipv6/route.c:1350 [inline]
> [<ffff80008a1643fc>] ip6_route_add+0x7c/0x220 net/ipv6/route.c:3900
> stacktrace:
>       __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
>       _raw_spin_lock_bh+0x5c/0xd0 kernel/locking/spinlock.c:178
>       spin_lock_bh include/linux/spinlock.h:356 [inline]
>       __ip6_ins_rt net/ipv6/route.c:1350 [inline]
>       ip6_route_add+0x7c/0x220 net/ipv6/route.c:3900
>       addrconf_prefix_route+0x28c/0x494 net/ipv6/addrconf.c:2487
>       fixup_permanent_addr net/ipv6/addrconf.c:3602 [inline]
>       addrconf_permanent_addr net/ipv6/addrconf.c:3626 [inline]
>       addrconf_notify+0xfd0/0x1688 net/ipv6/addrconf.c:3698
>       notifier_call_chain+0x94/0x50c kernel/notifier.c:85
>       raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453
>       call_netdevice_notifiers_info+0xb8/0x150 net/core/dev.c:2176
>       call_netdevice_notifiers_extack net/core/dev.c:2214 [inline]
>       call_netdevice_notifiers net/core/dev.c:2228 [inline]
>       __dev_notify_flags+0x114/0x294 net/core/dev.c:9393
>       netif_change_flags+0x108/0x160 net/core/dev.c:9422
>       do_setlink.isra.0+0x960/0x3464 net/core/rtnetlink.c:3152
>       rtnl_changelink net/core/rtnetlink.c:3769 [inline]
>       __rtnl_newlink net/core/rtnetlink.c:3928 [inline]
>       rtnl_newlink+0x1080/0x1a1c net/core/rtnetlink.c:4065
>       rtnetlink_rcv_msg+0x82c/0xc30 net/core/rtnetlink.c:6955
>       netlink_rcv_skb+0x218/0x400 net/netlink/af_netlink.c:2534
>       rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6982
>       netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
>       netlink_unicast+0x50c/0x778 net/netlink/af_netlink.c:1339
>       netlink_sendmsg+0x794/0xc28 net/netlink/af_netlink.c:1883
> 
> [E] write_unlock(&ndev->lock:0):
> (N/A)
> ---------------------------------------------------
> context D's detail
> ---------------------------------------------------
> context D
>    [S] lock(&vn->busy.lock:0)
>    [W] write_lock(&ndev->lock:0)
>    [E] unlock(&vn->busy.lock:0)
> 
> [S] lock(&vn->busy.lock:0):
> [<ffff800080adcf80>] spin_lock include/linux/spinlock.h:351 [inline]
> [<ffff800080adcf80>] alloc_vmap_area+0x800/0x26d0 mm/vmalloc.c:2027
> stacktrace:
>       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
>       _raw_spin_lock+0x78/0xc0 kernel/locking/spinlock.c:154
>       spin_lock include/linux/spinlock.h:351 [inline]
>       alloc_vmap_area+0x800/0x26d0 mm/vmalloc.c:2027
>       __get_vm_area_node+0x1c8/0x360 mm/vmalloc.c:3138
>       __vmalloc_node_range_noprof+0x168/0x10d4 mm/vmalloc.c:3805
>       __vmalloc_node_noprof+0x130/0x178 mm/vmalloc.c:3908
>       vzalloc_noprof+0x3c/0x54 mm/vmalloc.c:3981
>       alloc_counters net/ipv6/netfilter/ip6_tables.c:815 [inline]
>       copy_entries_to_user net/ipv6/netfilter/ip6_tables.c:837 [inline]
>       get_entries net/ipv6/netfilter/ip6_tables.c:1039 [inline]
>       do_ip6t_get_ctl+0x520/0xad0 net/ipv6/netfilter/ip6_tables.c:1677
>       nf_getsockopt+0x8c/0x10c net/netfilter/nf_sockopt.c:116
>       ipv6_getsockopt+0x24c/0x460 net/ipv6/ipv6_sockglue.c:1493
>       tcp_getsockopt+0x98/0x120 net/ipv4/tcp.c:4727
>       sock_common_getsockopt+0x9c/0xcc net/core/sock.c:3867
>       do_sock_getsockopt+0x308/0x57c net/socket.c:2357
>       __sys_getsockopt+0xec/0x188 net/socket.c:2386
>       __do_sys_getsockopt net/socket.c:2393 [inline]
>       __se_sys_getsockopt net/socket.c:2390 [inline]
>       __arm64_sys_getsockopt+0xa8/0x110 net/socket.c:2390
>       __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline]
>       invoke_syscall+0x88/0x2e0 arch/arm64/kernel/syscall.c:50
>       el0_svc_common.constprop.0+0xe8/0x2e0 arch/arm64/kernel/syscall.c:139
> 
> [W] write_lock(&ndev->lock:0):
> [<ffff80008a127f20>] addrconf_rs_timer+0xa0/0x730 net/ipv6/addrconf.c:4025
> stacktrace:
>       __raw_write_lock include/linux/rwlock_api_smp.h:209 [inline]
>       _raw_write_lock+0x5c/0xd0 kernel/locking/spinlock.c:300
>       addrconf_rs_timer+0xa0/0x730 net/ipv6/addrconf.c:4025
>       call_timer_fn+0x204/0x964 kernel/time/timer.c:1789
>       expire_timers kernel/time/timer.c:1840 [inline]
>       __run_timers+0x830/0xb00 kernel/time/timer.c:2414
>       __run_timer_base kernel/time/timer.c:2426 [inline]
>       __run_timer_base kernel/time/timer.c:2418 [inline]
>       run_timer_base+0x124/0x198 kernel/time/timer.c:2435
>       run_timer_softirq+0x20/0x58 kernel/time/timer.c:2445
>       handle_softirqs+0x30c/0xdc0 kernel/softirq.c:579
>       __do_softirq+0x14/0x20 kernel/softirq.c:613
>       ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:81
>       call_on_irq_stack+0x24/0x30 arch/arm64/kernel/entry.S:891
>       do_softirq_own_stack+0x20/0x40 arch/arm64/kernel/irq.c:86
>       invoke_softirq kernel/softirq.c:460 [inline]
>       __irq_exit_rcu+0x400/0x560 kernel/softirq.c:680
>       irq_exit_rcu+0x14/0x80 kernel/softirq.c:696
>       __el1_irq arch/arm64/kernel/entry-common.c:561 [inline]
>       el1_interrupt+0x38/0x54 arch/arm64/kernel/entry-common.c:575
>       el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:580
>       el1h_64_irq+0x6c/0x70 arch/arm64/kernel/entry.S:596
> 
> [E] unlock(&vn->busy.lock:0):
> (N/A)
> ---------------------------------------------------
> information that might be helpful
> ---------------------------------------------------
> CPU: 1 UID: 0 PID: 19536 Comm: syz.4.2592 Not tainted 6.15.0-rc6-00043-ga83a69ec7f9f #5 PREEMPT
> Hardware name: QEMU KVM Virtual Machine, BIOS 2025.02-8 05/13/2025
> Call trace:
>  dump_backtrace arch/arm64/kernel/stacktrace.c:449 [inline] (C)
>  show_stack+0x34/0x80 arch/arm64/kernel/stacktrace.c:466 (C)
>  __dump_stack lib/dump_stack.c:94 [inline]
>  dump_stack_lvl+0x104/0x180 lib/dump_stack.c:120
>  dump_stack+0x20/0x2c lib/dump_stack.c:129
>  print_circle kernel/dependency/dept.c:928 [inline]
>  cb_check_dl kernel/dependency/dept.c:1362 [inline]
>  cb_check_dl+0x1080/0x10ec kernel/dependency/dept.c:1356
>  bfs+0x4d8/0x630 kernel/dependency/dept.c:980
>  check_dl_bfs kernel/dependency/dept.c:1381 [inline]
>  add_dep+0x1cc/0x364 kernel/dependency/dept.c:1710
>  add_wait kernel/dependency/dept.c:1829 [inline]
>  __dept_wait+0x60c/0x16e0 kernel/dependency/dept.c:2585
>  dept_wait kernel/dependency/dept.c:2666 [inline]
>  dept_wait+0x168/0x1a8 kernel/dependency/dept.c:2640
>  __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
>  _raw_spin_lock+0x54/0xc0 kernel/locking/spinlock.c:154
>  spin_lock include/linux/spinlock.h:351 [inline]
>  find_vmap_area+0xa0/0x228 mm/vmalloc.c:2418
>  find_vm_area+0x20/0x68 mm/vmalloc.c:3208
>  kasan_find_vm_area mm/kasan/report.c:398 [inline]
>  print_address_description mm/kasan/report.c:432 [inline]
>  print_report+0x3d8/0x54c mm/kasan/report.c:521
>  kasan_report+0xb8/0x1d4 mm/kasan/report.c:634
>  __asan_report_load4_noabort+0x20/0x2c mm/kasan/report_generic.c:380
>  fib6_ifdown+0x67c/0x6bc net/ipv6/route.c:4910
>  fib6_clean_node+0x23c/0x4e0 net/ipv6/ip6_fib.c:2199
>  fib6_walk_continue+0x38c/0x774 net/ipv6/ip6_fib.c:2124
>  fib6_walk+0x158/0x31c net/ipv6/ip6_fib.c:2172
>  fib6_clean_tree+0xe0/0x128 net/ipv6/ip6_fib.c:2252
>  __fib6_clean_all+0x104/0x2b8 net/ipv6/ip6_fib.c:2268
>  fib6_clean_all+0x3c/0x50 net/ipv6/ip6_fib.c:2279
>  rt6_sync_down_dev net/ipv6/route.c:4951 [inline]
>  rt6_disable_ip+0x270/0x840 net/ipv6/route.c:4956
>  addrconf_ifdown.isra.0+0x104/0x175c net/ipv6/addrconf.c:3857
>  addrconf_notify+0x3a0/0x1688 net/ipv6/addrconf.c:3780
>  notifier_call_chain+0x94/0x50c kernel/notifier.c:85
>  raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453
>  call_netdevice_notifiers_info+0xb8/0x150 net/core/dev.c:2176
>  call_netdevice_notifiers_extack net/core/dev.c:2214 [inline]
>  call_netdevice_notifiers net/core/dev.c:2228 [inline]
>  dev_close_many+0x290/0x4b8 net/core/dev.c:1731
>  unregister_netdevice_many_notify+0x574/0x1fa0 net/core/dev.c:11940
>  unregister_netdevice_many net/core/dev.c:12034 [inline]
>  unregister_netdevice_queue+0x2b8/0x390 net/core/dev.c:11877
>  unregister_netdevice include/linux/netdevice.h:3374 [inline]
>  __tun_detach+0xec4/0x1180 drivers/net/tun.c:620
>  tun_detach drivers/net/tun.c:636 [inline]
>  tun_chr_close+0xa4/0x248 drivers/net/tun.c:3390
>  __fput+0x374/0xa30 fs/file_table.c:465
>  ____fput+0x20/0x3c fs/file_table.c:493
>  task_work_run+0x154/0x278 kernel/task_work.c:227
>  exit_task_work include/linux/task_work.h:40 [inline]
>  do_exit+0x950/0x23a8 kernel/exit.c:953
>  do_group_exit+0xc0/0x248 kernel/exit.c:1103
>  get_signal+0x1f98/0x20cc kernel/signal.c:3034
>  do_signal+0x200/0x880 arch/arm64/kernel/signal.c:1658
>  do_notify_resume+0x1a0/0x26c arch/arm64/kernel/entry-common.c:148
>  exit_to_user_mode_prepare arch/arm64/kernel/entry-common.c:169 [inline]
>  exit_to_user_mode arch/arm64/kernel/entry-common.c:178 [inline]
>  el0_svc+0xf8/0x188 arch/arm64/kernel/entry-common.c:745
>  el0t_64_sync_handler+0x10c/0x140 arch/arm64/kernel/entry-common.c:762
>  el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
> 
> ---
>  mm/kasan/report.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> index 8357e1a33699..61c590e8005e 100644
> --- a/mm/kasan/report.c
> +++ b/mm/kasan/report.c
> @@ -387,7 +387,7 @@ static inline struct vm_struct *kasan_find_vm_area(void *addr)
>         static DEFINE_WAIT_OVERRIDE_MAP(vmalloc_map, LD_WAIT_SLEEP);
>         struct vm_struct *va;
> 
> -       if (IS_ENABLED(CONFIG_PREEMPT_RT))
> +       if (IS_ENABLED(CONFIG_PREEMPT_RT) || in_interrupt())
>                 return NULL;
> 
>         /*
> --
> LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}
>

On Wed, Jul 02, 2025 at 03:01:38PM +0900, Byungchul Park wrote:
> On Tue, Jul 01, 2025 at 09:35:45PM +0100, Yeoreum Yun wrote:
> > 
> > 
> > Caution: External Email. Please take care when clicking links or opening attachments.
> > 
> > 
> > 
> > 
> > 
> > 
> > In below senario, kasan causes deadlock while reporting vm area informaion:
> > 
> > CPU0                                CPU1
> > vmalloc();
> >  alloc_vmap_area();
> >   spin_lock(&vn->busy.lock)
> 			^
> 	Here, it should be spin_lock_bh(&vn->busy.lock).

spin_lock_irqsave(&vn->busy.lock) might be even better, assuming
find_vm_area() could be called with a critcal section of *_irq() or
something.

	Byungchul
> 
> >                                     spin_lock_bh(&some_lock);
> >    <interrupt occurs>
> >    <in softirq>
> >    spin_lock(&some_lock);
> >                                     <access invalid address>
> >                                     kasan_report();
> >                                      print_report();
> >                                       print_address_description();
> >                                        kasan_find_vm_area();
> >                                         find_vm_area();
> >                                          spin_lock(&vn->busy.lock) // deadlock!
> 						^
> 		It should be spin_lock_bh(&vn->busy.lock), since it can
> 		be within a critical section of *spin_lock_bh*() to
> 		avoid a deadlock with softirq involved.
> 
> 	Byungchul
> 
> > To resolve this possible deadlock, don't call find_vm_area()
> > to prevent possible deadlock while kasan reports vm area information.
> > 
> > Fixes: c056a364e954 ("kasan: print virtual mapping info in reports")
> > Reported-by: Yunseong Kim <ysk@kzalloc.com>
> > Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
> > ---
> > Below report is from Yunseong Kim using DEPT:
> > 
> > ===================================================
> > DEPT: Circular dependency has been detected.
> > 6.15.0-rc6-00043-ga83a69ec7f9f #5 Not tainted
> > ---------------------------------------------------
> > summary
> > ---------------------------------------------------
> > *** DEADLOCK ***
> > 
> > context A
> >    [S] lock(report_lock:0)
> >    [W] lock(&vn->busy.lock:0)
> >    [E] unlock(report_lock:0)
> > 
> > context B
> >    [S] lock(&tb->tb6_lock:0)
> >    [W] lock(report_lock:0)
> >    [E] unlock(&tb->tb6_lock:0)
> > 
> > context C
> >    [S] write_lock(&ndev->lock:0)
> >    [W] lock(&tb->tb6_lock:0)
> >    [E] write_unlock(&ndev->lock:0)
> > 
> > context D
> >    [S] lock(&vn->busy.lock:0)
> >    [W] write_lock(&ndev->lock:0)
> >    [E] unlock(&vn->busy.lock:0)
> > 
> > [S]: start of the event context
> > [W]: the wait blocked
> > [E]: the event not reachable
> > ---------------------------------------------------
> > context A's detail
> > ---------------------------------------------------
> > context A
> >    [S] lock(report_lock:0)
> >    [W] lock(&vn->busy.lock:0)
> >    [E] unlock(report_lock:0)
> > 
> > [S] lock(report_lock:0):
> > [<ffff800080bd2600>] start_report mm/kasan/report.c:215 [inline]
> > [<ffff800080bd2600>] kasan_report+0x74/0x1d4 mm/kasan/report.c:623
> > stacktrace:
> >       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
> >       _raw_spin_lock_irqsave+0x88/0xd8 kernel/locking/spinlock.c:162
> >       start_report mm/kasan/report.c:215 [inline]
> >       kasan_report+0x74/0x1d4 mm/kasan/report.c:623
> >       __asan_report_load4_noabort+0x20/0x2c mm/kasan/report_generic.c:380
> >       fib6_ifdown+0x67c/0x6bc net/ipv6/route.c:4910
> >       fib6_clean_node+0x23c/0x4e0 net/ipv6/ip6_fib.c:2199
> >       fib6_walk_continue+0x38c/0x774 net/ipv6/ip6_fib.c:2124
> >       fib6_walk+0x158/0x31c net/ipv6/ip6_fib.c:2172
> >       fib6_clean_tree+0xe0/0x128 net/ipv6/ip6_fib.c:2252
> >       __fib6_clean_all+0x104/0x2b8 net/ipv6/ip6_fib.c:2268
> >       fib6_clean_all+0x3c/0x50 net/ipv6/ip6_fib.c:2279
> >       rt6_sync_down_dev net/ipv6/route.c:4951 [inline]
> >       rt6_disable_ip+0x270/0x840 net/ipv6/route.c:4956
> >       addrconf_ifdown.isra.0+0x104/0x175c net/ipv6/addrconf.c:3857
> >       addrconf_notify+0x3a0/0x1688 net/ipv6/addrconf.c:3780
> >       notifier_call_chain+0x94/0x50c kernel/notifier.c:85
> >       raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453
> >       call_netdevice_notifiers_info+0xb8/0x150 net/core/dev.c:2176
> > 
> > [W] lock(&vn->busy.lock:0):
> > [<ffff800080ae57a0>] spin_lock include/linux/spinlock.h:351 [inline]
> > [<ffff800080ae57a0>] find_vmap_area+0xa0/0x228 mm/vmalloc.c:2418
> > stacktrace:
> >       spin_lock include/linux/spinlock.h:351 [inline]
> >       find_vmap_area+0xa0/0x228 mm/vmalloc.c:2418
> >       find_vm_area+0x20/0x68 mm/vmalloc.c:3208
> >       kasan_find_vm_area mm/kasan/report.c:398 [inline]
> >       print_address_description mm/kasan/report.c:432 [inline]
> >       print_report+0x3d8/0x54c mm/kasan/report.c:521
> >       kasan_report+0xb8/0x1d4 mm/kasan/report.c:634
> >       __asan_report_load4_noabort+0x20/0x2c mm/kasan/report_generic.c:380
> >       fib6_ifdown+0x67c/0x6bc net/ipv6/route.c:4910
> >       fib6_clean_node+0x23c/0x4e0 net/ipv6/ip6_fib.c:2199
> >       fib6_walk_continue+0x38c/0x774 net/ipv6/ip6_fib.c:2124
> >       fib6_walk+0x158/0x31c net/ipv6/ip6_fib.c:2172
> >       fib6_clean_tree+0xe0/0x128 net/ipv6/ip6_fib.c:2252
> >       __fib6_clean_all+0x104/0x2b8 net/ipv6/ip6_fib.c:2268
> >       fib6_clean_all+0x3c/0x50 net/ipv6/ip6_fib.c:2279
> >       rt6_sync_down_dev net/ipv6/route.c:4951 [inline]
> >       rt6_disable_ip+0x270/0x840 net/ipv6/route.c:4956
> >       addrconf_ifdown.isra.0+0x104/0x175c net/ipv6/addrconf.c:3857
> >       addrconf_notify+0x3a0/0x1688 net/ipv6/addrconf.c:3780
> >       notifier_call_chain+0x94/0x50c kernel/notifier.c:85
> > 
> > [E] unlock(report_lock:0):
> > (N/A)
> > ---------------------------------------------------
> > context B's detail
> > ---------------------------------------------------
> > context B
> >    [S] lock(&tb->tb6_lock:0)
> >    [W] lock(report_lock:0)
> >    [E] unlock(&tb->tb6_lock:0)
> > 
> > [S] lock(&tb->tb6_lock:0):
> > [<ffff80008a172d10>] spin_lock_bh include/linux/spinlock.h:356 [inline]
> > [<ffff80008a172d10>] __fib6_clean_all+0xe8/0x2b8 net/ipv6/ip6_fib.c:2267
> > stacktrace:
> >       __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
> >       _raw_spin_lock_bh+0x80/0xd0 kernel/locking/spinlock.c:178
> >       spin_lock_bh include/linux/spinlock.h:356 [inline]
> >       __fib6_clean_all+0xe8/0x2b8 net/ipv6/ip6_fib.c:2267
> >       fib6_clean_all+0x3c/0x50 net/ipv6/ip6_fib.c:2279
> >       rt6_sync_down_dev net/ipv6/route.c:4951 [inline]
> >       rt6_disable_ip+0x270/0x840 net/ipv6/route.c:4956
> >       addrconf_ifdown.isra.0+0x104/0x175c net/ipv6/addrconf.c:3857
> >       addrconf_notify+0x3a0/0x1688 net/ipv6/addrconf.c:3780
> >       notifier_call_chain+0x94/0x50c kernel/notifier.c:85
> >       raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453
> >       call_netdevice_notifiers_info+0xb8/0x150 net/core/dev.c:2176
> >       call_netdevice_notifiers_extack net/core/dev.c:2214 [inline]
> >       call_netdevice_notifiers net/core/dev.c:2228 [inline]
> >       dev_close_many+0x290/0x4b8 net/core/dev.c:1731
> >       unregister_netdevice_many_notify+0x574/0x1fa0 net/core/dev.c:11940
> >       unregister_netdevice_many net/core/dev.c:12034 [inline]
> >       unregister_netdevice_queue+0x2b8/0x390 net/core/dev.c:11877
> >       unregister_netdevice include/linux/netdevice.h:3374 [inline]
> >       __tun_detach+0xec4/0x1180 drivers/net/tun.c:620
> >       tun_detach drivers/net/tun.c:636 [inline]
> >       tun_chr_close+0xa4/0x248 drivers/net/tun.c:3390
> >       __fput+0x374/0xa30 fs/file_table.c:465
> >       ____fput+0x20/0x3c fs/file_table.c:493
> > 
> > [W] lock(report_lock:0):
> > [<ffff800080bd2600>] start_report mm/kasan/report.c:215 [inline]
> > [<ffff800080bd2600>] kasan_report+0x74/0x1d4 mm/kasan/report.c:623
> > stacktrace:
> >       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
> >       _raw_spin_lock_irqsave+0x6c/0xd8 kernel/locking/spinlock.c:162
> >       start_report mm/kasan/report.c:215 [inline]
> >       kasan_report+0x74/0x1d4 mm/kasan/report.c:623
> >       __asan_report_load4_noabort+0x20/0x2c mm/kasan/report_generic.c:380
> >       fib6_ifdown+0x67c/0x6bc net/ipv6/route.c:4910
> >       fib6_clean_node+0x23c/0x4e0 net/ipv6/ip6_fib.c:2199
> >       fib6_walk_continue+0x38c/0x774 net/ipv6/ip6_fib.c:2124
> >       fib6_walk+0x158/0x31c net/ipv6/ip6_fib.c:2172
> >       fib6_clean_tree+0xe0/0x128 net/ipv6/ip6_fib.c:2252
> >       __fib6_clean_all+0x104/0x2b8 net/ipv6/ip6_fib.c:2268
> >       fib6_clean_all+0x3c/0x50 net/ipv6/ip6_fib.c:2279
> >       rt6_sync_down_dev net/ipv6/route.c:4951 [inline]
> >       rt6_disable_ip+0x270/0x840 net/ipv6/route.c:4956
> >       addrconf_ifdown.isra.0+0x104/0x175c net/ipv6/addrconf.c:3857
> >       addrconf_notify+0x3a0/0x1688 net/ipv6/addrconf.c:3780
> >       notifier_call_chain+0x94/0x50c kernel/notifier.c:85
> >       raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453
> >       call_netdevice_notifiers_info+0xb8/0x150 net/core/dev.c:2176
> > 
> > [E] unlock(&tb->tb6_lock:0):
> > (N/A)
> > ---------------------------------------------------
> > context C's detail
> > ---------------------------------------------------
> > context C
> >    [S] write_lock(&ndev->lock:0)
> >    [W] lock(&tb->tb6_lock:0)
> >    [E] write_unlock(&ndev->lock:0)
> > 
> > [S] write_lock(&ndev->lock:0):
> > [<ffff80008a133bd8>] addrconf_permanent_addr net/ipv6/addrconf.c:3622 [inline]
> > [<ffff80008a133bd8>] addrconf_notify+0xab4/0x1688 net/ipv6/addrconf.c:3698
> > stacktrace:
> >       __raw_write_lock_bh include/linux/rwlock_api_smp.h:202 [inline]
> >       _raw_write_lock_bh+0x88/0xd4 kernel/locking/spinlock.c:334
> >       addrconf_permanent_addr net/ipv6/addrconf.c:3622 [inline]
> >       addrconf_notify+0xab4/0x1688 net/ipv6/addrconf.c:3698
> >       notifier_call_chain+0x94/0x50c kernel/notifier.c:85
> >       raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453
> >       call_netdevice_notifiers_info+0xb8/0x150 net/core/dev.c:2176
> >       call_netdevice_notifiers_extack net/core/dev.c:2214 [inline]
> >       call_netdevice_notifiers net/core/dev.c:2228 [inline]
> >       __dev_notify_flags+0x114/0x294 net/core/dev.c:9393
> >       netif_change_flags+0x108/0x160 net/core/dev.c:9422
> >       do_setlink.isra.0+0x960/0x3464 net/core/rtnetlink.c:3152
> >       rtnl_changelink net/core/rtnetlink.c:3769 [inline]
> >       __rtnl_newlink net/core/rtnetlink.c:3928 [inline]
> >       rtnl_newlink+0x1080/0x1a1c net/core/rtnetlink.c:4065
> >       rtnetlink_rcv_msg+0x82c/0xc30 net/core/rtnetlink.c:6955
> >       netlink_rcv_skb+0x218/0x400 net/netlink/af_netlink.c:2534
> >       rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6982
> >       netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
> >       netlink_unicast+0x50c/0x778 net/netlink/af_netlink.c:1339
> >       netlink_sendmsg+0x794/0xc28 net/netlink/af_netlink.c:1883
> >       sock_sendmsg_nosec net/socket.c:712 [inline]
> >       __sock_sendmsg+0xe0/0x1a0 net/socket.c:727
> >       __sys_sendto+0x238/0x2fc net/socket.c:2180
> > 
> > [W] lock(&tb->tb6_lock:0):
> > [<ffff80008a1643fc>] spin_lock_bh include/linux/spinlock.h:356 [inline]
> > [<ffff80008a1643fc>] __ip6_ins_rt net/ipv6/route.c:1350 [inline]
> > [<ffff80008a1643fc>] ip6_route_add+0x7c/0x220 net/ipv6/route.c:3900
> > stacktrace:
> >       __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]
> >       _raw_spin_lock_bh+0x5c/0xd0 kernel/locking/spinlock.c:178
> >       spin_lock_bh include/linux/spinlock.h:356 [inline]
> >       __ip6_ins_rt net/ipv6/route.c:1350 [inline]
> >       ip6_route_add+0x7c/0x220 net/ipv6/route.c:3900
> >       addrconf_prefix_route+0x28c/0x494 net/ipv6/addrconf.c:2487
> >       fixup_permanent_addr net/ipv6/addrconf.c:3602 [inline]
> >       addrconf_permanent_addr net/ipv6/addrconf.c:3626 [inline]
> >       addrconf_notify+0xfd0/0x1688 net/ipv6/addrconf.c:3698
> >       notifier_call_chain+0x94/0x50c kernel/notifier.c:85
> >       raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453
> >       call_netdevice_notifiers_info+0xb8/0x150 net/core/dev.c:2176
> >       call_netdevice_notifiers_extack net/core/dev.c:2214 [inline]
> >       call_netdevice_notifiers net/core/dev.c:2228 [inline]
> >       __dev_notify_flags+0x114/0x294 net/core/dev.c:9393
> >       netif_change_flags+0x108/0x160 net/core/dev.c:9422
> >       do_setlink.isra.0+0x960/0x3464 net/core/rtnetlink.c:3152
> >       rtnl_changelink net/core/rtnetlink.c:3769 [inline]
> >       __rtnl_newlink net/core/rtnetlink.c:3928 [inline]
> >       rtnl_newlink+0x1080/0x1a1c net/core/rtnetlink.c:4065
> >       rtnetlink_rcv_msg+0x82c/0xc30 net/core/rtnetlink.c:6955
> >       netlink_rcv_skb+0x218/0x400 net/netlink/af_netlink.c:2534
> >       rtnetlink_rcv+0x28/0x38 net/core/rtnetlink.c:6982
> >       netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline]
> >       netlink_unicast+0x50c/0x778 net/netlink/af_netlink.c:1339
> >       netlink_sendmsg+0x794/0xc28 net/netlink/af_netlink.c:1883
> > 
> > [E] write_unlock(&ndev->lock:0):
> > (N/A)
> > ---------------------------------------------------
> > context D's detail
> > ---------------------------------------------------
> > context D
> >    [S] lock(&vn->busy.lock:0)
> >    [W] write_lock(&ndev->lock:0)
> >    [E] unlock(&vn->busy.lock:0)
> > 
> > [S] lock(&vn->busy.lock:0):
> > [<ffff800080adcf80>] spin_lock include/linux/spinlock.h:351 [inline]
> > [<ffff800080adcf80>] alloc_vmap_area+0x800/0x26d0 mm/vmalloc.c:2027
> > stacktrace:
> >       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
> >       _raw_spin_lock+0x78/0xc0 kernel/locking/spinlock.c:154
> >       spin_lock include/linux/spinlock.h:351 [inline]
> >       alloc_vmap_area+0x800/0x26d0 mm/vmalloc.c:2027
> >       __get_vm_area_node+0x1c8/0x360 mm/vmalloc.c:3138
> >       __vmalloc_node_range_noprof+0x168/0x10d4 mm/vmalloc.c:3805
> >       __vmalloc_node_noprof+0x130/0x178 mm/vmalloc.c:3908
> >       vzalloc_noprof+0x3c/0x54 mm/vmalloc.c:3981
> >       alloc_counters net/ipv6/netfilter/ip6_tables.c:815 [inline]
> >       copy_entries_to_user net/ipv6/netfilter/ip6_tables.c:837 [inline]
> >       get_entries net/ipv6/netfilter/ip6_tables.c:1039 [inline]
> >       do_ip6t_get_ctl+0x520/0xad0 net/ipv6/netfilter/ip6_tables.c:1677
> >       nf_getsockopt+0x8c/0x10c net/netfilter/nf_sockopt.c:116
> >       ipv6_getsockopt+0x24c/0x460 net/ipv6/ipv6_sockglue.c:1493
> >       tcp_getsockopt+0x98/0x120 net/ipv4/tcp.c:4727
> >       sock_common_getsockopt+0x9c/0xcc net/core/sock.c:3867
> >       do_sock_getsockopt+0x308/0x57c net/socket.c:2357
> >       __sys_getsockopt+0xec/0x188 net/socket.c:2386
> >       __do_sys_getsockopt net/socket.c:2393 [inline]
> >       __se_sys_getsockopt net/socket.c:2390 [inline]
> >       __arm64_sys_getsockopt+0xa8/0x110 net/socket.c:2390
> >       __invoke_syscall arch/arm64/kernel/syscall.c:36 [inline]
> >       invoke_syscall+0x88/0x2e0 arch/arm64/kernel/syscall.c:50
> >       el0_svc_common.constprop.0+0xe8/0x2e0 arch/arm64/kernel/syscall.c:139
> > 
> > [W] write_lock(&ndev->lock:0):
> > [<ffff80008a127f20>] addrconf_rs_timer+0xa0/0x730 net/ipv6/addrconf.c:4025
> > stacktrace:
> >       __raw_write_lock include/linux/rwlock_api_smp.h:209 [inline]
> >       _raw_write_lock+0x5c/0xd0 kernel/locking/spinlock.c:300
> >       addrconf_rs_timer+0xa0/0x730 net/ipv6/addrconf.c:4025
> >       call_timer_fn+0x204/0x964 kernel/time/timer.c:1789
> >       expire_timers kernel/time/timer.c:1840 [inline]
> >       __run_timers+0x830/0xb00 kernel/time/timer.c:2414
> >       __run_timer_base kernel/time/timer.c:2426 [inline]
> >       __run_timer_base kernel/time/timer.c:2418 [inline]
> >       run_timer_base+0x124/0x198 kernel/time/timer.c:2435
> >       run_timer_softirq+0x20/0x58 kernel/time/timer.c:2445
> >       handle_softirqs+0x30c/0xdc0 kernel/softirq.c:579
> >       __do_softirq+0x14/0x20 kernel/softirq.c:613
> >       ____do_softirq+0x14/0x20 arch/arm64/kernel/irq.c:81
> >       call_on_irq_stack+0x24/0x30 arch/arm64/kernel/entry.S:891
> >       do_softirq_own_stack+0x20/0x40 arch/arm64/kernel/irq.c:86
> >       invoke_softirq kernel/softirq.c:460 [inline]
> >       __irq_exit_rcu+0x400/0x560 kernel/softirq.c:680
> >       irq_exit_rcu+0x14/0x80 kernel/softirq.c:696
> >       __el1_irq arch/arm64/kernel/entry-common.c:561 [inline]
> >       el1_interrupt+0x38/0x54 arch/arm64/kernel/entry-common.c:575
> >       el1h_64_irq_handler+0x18/0x24 arch/arm64/kernel/entry-common.c:580
> >       el1h_64_irq+0x6c/0x70 arch/arm64/kernel/entry.S:596
> > 
> > [E] unlock(&vn->busy.lock:0):
> > (N/A)
> > ---------------------------------------------------
> > information that might be helpful
> > ---------------------------------------------------
> > CPU: 1 UID: 0 PID: 19536 Comm: syz.4.2592 Not tainted 6.15.0-rc6-00043-ga83a69ec7f9f #5 PREEMPT
> > Hardware name: QEMU KVM Virtual Machine, BIOS 2025.02-8 05/13/2025
> > Call trace:
> >  dump_backtrace arch/arm64/kernel/stacktrace.c:449 [inline] (C)
> >  show_stack+0x34/0x80 arch/arm64/kernel/stacktrace.c:466 (C)
> >  __dump_stack lib/dump_stack.c:94 [inline]
> >  dump_stack_lvl+0x104/0x180 lib/dump_stack.c:120
> >  dump_stack+0x20/0x2c lib/dump_stack.c:129
> >  print_circle kernel/dependency/dept.c:928 [inline]
> >  cb_check_dl kernel/dependency/dept.c:1362 [inline]
> >  cb_check_dl+0x1080/0x10ec kernel/dependency/dept.c:1356
> >  bfs+0x4d8/0x630 kernel/dependency/dept.c:980
> >  check_dl_bfs kernel/dependency/dept.c:1381 [inline]
> >  add_dep+0x1cc/0x364 kernel/dependency/dept.c:1710
> >  add_wait kernel/dependency/dept.c:1829 [inline]
> >  __dept_wait+0x60c/0x16e0 kernel/dependency/dept.c:2585
> >  dept_wait kernel/dependency/dept.c:2666 [inline]
> >  dept_wait+0x168/0x1a8 kernel/dependency/dept.c:2640
> >  __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
> >  _raw_spin_lock+0x54/0xc0 kernel/locking/spinlock.c:154
> >  spin_lock include/linux/spinlock.h:351 [inline]
> >  find_vmap_area+0xa0/0x228 mm/vmalloc.c:2418
> >  find_vm_area+0x20/0x68 mm/vmalloc.c:3208
> >  kasan_find_vm_area mm/kasan/report.c:398 [inline]
> >  print_address_description mm/kasan/report.c:432 [inline]
> >  print_report+0x3d8/0x54c mm/kasan/report.c:521
> >  kasan_report+0xb8/0x1d4 mm/kasan/report.c:634
> >  __asan_report_load4_noabort+0x20/0x2c mm/kasan/report_generic.c:380
> >  fib6_ifdown+0x67c/0x6bc net/ipv6/route.c:4910
> >  fib6_clean_node+0x23c/0x4e0 net/ipv6/ip6_fib.c:2199
> >  fib6_walk_continue+0x38c/0x774 net/ipv6/ip6_fib.c:2124
> >  fib6_walk+0x158/0x31c net/ipv6/ip6_fib.c:2172
> >  fib6_clean_tree+0xe0/0x128 net/ipv6/ip6_fib.c:2252
> >  __fib6_clean_all+0x104/0x2b8 net/ipv6/ip6_fib.c:2268
> >  fib6_clean_all+0x3c/0x50 net/ipv6/ip6_fib.c:2279
> >  rt6_sync_down_dev net/ipv6/route.c:4951 [inline]
> >  rt6_disable_ip+0x270/0x840 net/ipv6/route.c:4956
> >  addrconf_ifdown.isra.0+0x104/0x175c net/ipv6/addrconf.c:3857
> >  addrconf_notify+0x3a0/0x1688 net/ipv6/addrconf.c:3780
> >  notifier_call_chain+0x94/0x50c kernel/notifier.c:85
> >  raw_notifier_call_chain+0x3c/0x50 kernel/notifier.c:453
> >  call_netdevice_notifiers_info+0xb8/0x150 net/core/dev.c:2176
> >  call_netdevice_notifiers_extack net/core/dev.c:2214 [inline]
> >  call_netdevice_notifiers net/core/dev.c:2228 [inline]
> >  dev_close_many+0x290/0x4b8 net/core/dev.c:1731
> >  unregister_netdevice_many_notify+0x574/0x1fa0 net/core/dev.c:11940
> >  unregister_netdevice_many net/core/dev.c:12034 [inline]
> >  unregister_netdevice_queue+0x2b8/0x390 net/core/dev.c:11877
> >  unregister_netdevice include/linux/netdevice.h:3374 [inline]
> >  __tun_detach+0xec4/0x1180 drivers/net/tun.c:620
> >  tun_detach drivers/net/tun.c:636 [inline]
> >  tun_chr_close+0xa4/0x248 drivers/net/tun.c:3390
> >  __fput+0x374/0xa30 fs/file_table.c:465
> >  ____fput+0x20/0x3c fs/file_table.c:493
> >  task_work_run+0x154/0x278 kernel/task_work.c:227
> >  exit_task_work include/linux/task_work.h:40 [inline]
> >  do_exit+0x950/0x23a8 kernel/exit.c:953
> >  do_group_exit+0xc0/0x248 kernel/exit.c:1103
> >  get_signal+0x1f98/0x20cc kernel/signal.c:3034
> >  do_signal+0x200/0x880 arch/arm64/kernel/signal.c:1658
> >  do_notify_resume+0x1a0/0x26c arch/arm64/kernel/entry-common.c:148
> >  exit_to_user_mode_prepare arch/arm64/kernel/entry-common.c:169 [inline]
> >  exit_to_user_mode arch/arm64/kernel/entry-common.c:178 [inline]
> >  el0_svc+0xf8/0x188 arch/arm64/kernel/entry-common.c:745
> >  el0t_64_sync_handler+0x10c/0x140 arch/arm64/kernel/entry-common.c:762
> >  el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
> > 
> > ---
> >  mm/kasan/report.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/mm/kasan/report.c b/mm/kasan/report.c
> > index 8357e1a33699..61c590e8005e 100644
> > --- a/mm/kasan/report.c
> > +++ b/mm/kasan/report.c
> > @@ -387,7 +387,7 @@ static inline struct vm_struct *kasan_find_vm_area(void *addr)
> >         static DEFINE_WAIT_OVERRIDE_MAP(vmalloc_map, LD_WAIT_SLEEP);
> >         struct vm_struct *va;
> > 
> > -       if (IS_ENABLED(CONFIG_PREEMPT_RT))
> > +       if (IS_ENABLED(CONFIG_PREEMPT_RT) || in_interrupt())
> >                 return NULL;
> > 
> >         /*
> > --
> > LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}
> >

Hi Byungchul,

> > >
> > > CPU0                                CPU1
> > > vmalloc();
> > >  alloc_vmap_area();
> > >   spin_lock(&vn->busy.lock)
> > 			^
> > 	Here, it should be spin_lock_bh(&vn->busy.lock).
>
> spin_lock_irqsave(&vn->busy.lock) might be even better, assuming
> find_vm_area() could be called with a critcal section of *_irq() or
> something.

Agree for this change and I also thought about it.
But, I'm not sure changing to spin_lock_irqsave() is *better*
since it makes a unexpected schedule delay whenever
vmalloc_info_show() is called via proc.

Also, I think the find_vm_area() is designed for task context not
for atomic context. so it seems the misusage in the kasan.

Am I missing something?

Thanks.

--
Sincerely,
Yeoreum Yun