Hi Eric, On Fri, Jan 17, 2025 at 5:14 AM 'Eric Dumazet' via syzkaller-bugs <syzkaller-bugs@xxxxxxxxxxxxxxxx> wrote: > > On Fri, Jan 17, 2025 at 4:58 AM syzbot > <syzbot+5b9196ecf74447172a9a@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > syzbot has found a reproducer for the following issue on: > > > > HEAD commit: 8d20dcda404d selftests: drv-net-hw: inject pp_alloc_fail e.. > > git tree: net-next > > console output: https://syzkaller.appspot.com/x/log.txt?x=14ef5a18580000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=c30f048a4f12891 > > dashboard link: https://syzkaller.appspot.com/bug?extid=5b9196ecf74447172a9a > > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=15d7a1f8580000 > > > > Downloadable assets: > > disk image: https://storage.googleapis.com/syzbot-assets/5ce07c743ced/disk-8d20dcda.raw.xz > > vmlinux: https://storage.googleapis.com/syzbot-assets/66f2a9a35d5e/vmlinux-8d20dcda.xz > > kernel image: https://storage.googleapis.com/syzbot-assets/4c790c086a46/bzImage-8d20dcda.xz > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+5b9196ecf74447172a9a@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > ====================================================== > > WARNING: possible circular locking dependency detected > > 6.13.0-rc7-syzkaller-01131-g8d20dcda404d #0 Not tainted > > ------------------------------------------------------ > > kworker/u8:6/3534 is trying to acquire lock: > > ffffffff8fcb4a08 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_acquire_if_cleanup_net net/core/dev.c:10281 [inline] > > ffffffff8fcb4a08 (rtnl_mutex){+.+.}-{4:4}, at: unregister_netdevice_many_notify+0xac2/0x2030 net/core/dev.c:11783 > > > > but task is already holding lock: > > ffff8880216b0768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: class_wiphy_constructor include/net/cfg80211.h:6034 [inline] > > ffff8880216b0768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: ieee80211_remove_interfaces+0x129/0x700 net/mac80211/iface.c:2276 > > > > which lock already depends on the new lock. > > > > > > the existing dependency chain (in reverse order) is: > > > > -> #1 (&rdev->wiphy.mtx){+.+.}-{4:4}: > > lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849 > > __mutex_lock_common kernel/locking/mutex.c:585 [inline] > > __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735 > > wiphy_lock include/net/cfg80211.h:6019 [inline] > > wiphy_register+0x1a49/0x27b0 net/wireless/core.c:1006 > > ieee80211_register_hw+0x30fb/0x3e10 net/mac80211/main.c:1582 > > mac80211_hwsim_new_radio+0x2a9f/0x4a90 drivers/net/wireless/virtual/mac80211_hwsim.c:5558 > > init_mac80211_hwsim+0x87a/0xb00 drivers/net/wireless/virtual/mac80211_hwsim.c:6910 > > do_one_initcall+0x248/0x870 init/main.c:1266 > > do_initcall_level+0x157/0x210 init/main.c:1328 > > do_initcalls+0x3f/0x80 init/main.c:1344 > > kernel_init_freeable+0x435/0x5d0 init/main.c:1577 > > kernel_init+0x1d/0x2b0 init/main.c:1466 > > ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 > > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > > > > -> #0 (rtnl_mutex){+.+.}-{4:4}: > > check_prev_add kernel/locking/lockdep.c:3161 [inline] > > check_prevs_add kernel/locking/lockdep.c:3280 [inline] > > validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904 > > __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226 > > lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849 > > __mutex_lock_common kernel/locking/mutex.c:585 [inline] > > __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735 > > rtnl_acquire_if_cleanup_net net/core/dev.c:10281 [inline] > > unregister_netdevice_many_notify+0xac2/0x2030 net/core/dev.c:11783 > > unregister_netdevice_many net/core/dev.c:11866 [inline] > > unregister_netdevice_queue+0x303/0x370 net/core/dev.c:11732 > > unregister_netdevice include/linux/netdevice.h:3320 [inline] > > _cfg80211_unregister_wdev+0x163/0x590 net/wireless/core.c:1251 > > ieee80211_remove_interfaces+0x4ef/0x700 net/mac80211/iface.c:2301 > > ieee80211_unregister_hw+0x5d/0x2c0 net/mac80211/main.c:1676 > > mac80211_hwsim_del_radio+0x2c4/0x4c0 drivers/net/wireless/virtual/mac80211_hwsim.c:5664 > > hwsim_exit_net+0x5c1/0x670 drivers/net/wireless/virtual/mac80211_hwsim.c:6544 > > ops_exit_list net/core/net_namespace.c:172 [inline] > > cleanup_net+0x812/0xd60 net/core/net_namespace.c:652 > > process_one_work kernel/workqueue.c:3236 [inline] > > process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3317 > > worker_thread+0x870/0xd30 kernel/workqueue.c:3398 > > kthread+0x2f0/0x390 kernel/kthread.c:389 > > ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 > > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > > > > other info that might help us debug this: > > > > Possible unsafe locking scenario: > > > > CPU0 CPU1 > > ---- ---- > > lock(&rdev->wiphy.mtx); > > lock(rtnl_mutex); > > lock(&rdev->wiphy.mtx); > > lock(rtnl_mutex); > > > > *** DEADLOCK *** > > > > 4 locks held by kworker/u8:6/3534: > > #0: ffff88801baf5948 ((wq_completion)netns){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3211 [inline] > > #0: ffff88801baf5948 ((wq_completion)netns){+.+.}-{0:0}, at: process_scheduled_works+0x93b/0x1840 kernel/workqueue.c:3317 > > #1: ffffc9000d507d00 (net_cleanup_work){+.+.}-{0:0}, at: process_one_work kernel/workqueue.c:3212 [inline] > > #1: ffffc9000d507d00 (net_cleanup_work){+.+.}-{0:0}, at: process_scheduled_works+0x976/0x1840 kernel/workqueue.c:3317 > > #2: ffffffff8fca8290 (pernet_ops_rwsem){++++}-{4:4}, at: cleanup_net+0x17a/0xd60 net/core/net_namespace.c:606 > > #3: ffff8880216b0768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: class_wiphy_constructor include/net/cfg80211.h:6034 [inline] > > #3: ffff8880216b0768 (&rdev->wiphy.mtx){+.+.}-{4:4}, at: ieee80211_remove_interfaces+0x129/0x700 net/mac80211/iface.c:2276 > > > > stack backtrace: > > CPU: 1 UID: 0 PID: 3534 Comm: kworker/u8:6 Not tainted 6.13.0-rc7-syzkaller-01131-g8d20dcda404d #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024 > > Workqueue: netns cleanup_net > > Call Trace: > > <TASK> > > __dump_stack lib/dump_stack.c:94 [inline] > > dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120 > > print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2074 > > check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2206 > > check_prev_add kernel/locking/lockdep.c:3161 [inline] > > check_prevs_add kernel/locking/lockdep.c:3280 [inline] > > validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3904 > > __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5226 > > lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5849 > > __mutex_lock_common kernel/locking/mutex.c:585 [inline] > > __mutex_lock+0x1ac/0xee0 kernel/locking/mutex.c:735 > > rtnl_acquire_if_cleanup_net net/core/dev.c:10281 [inline] > > unregister_netdevice_many_notify+0xac2/0x2030 net/core/dev.c:11783 > > unregister_netdevice_many net/core/dev.c:11866 [inline] > > unregister_netdevice_queue+0x303/0x370 net/core/dev.c:11732 > > unregister_netdevice include/linux/netdevice.h:3320 [inline] > > _cfg80211_unregister_wdev+0x163/0x590 net/wireless/core.c:1251 > > ieee80211_remove_interfaces+0x4ef/0x700 net/mac80211/iface.c:2301 > > ieee80211_unregister_hw+0x5d/0x2c0 net/mac80211/main.c:1676 > > mac80211_hwsim_del_radio+0x2c4/0x4c0 drivers/net/wireless/virtual/mac80211_hwsim.c:5664 > > hwsim_exit_net+0x5c1/0x670 drivers/net/wireless/virtual/mac80211_hwsim.c:6544 > > ops_exit_list net/core/net_namespace.c:172 [inline] > > cleanup_net+0x812/0xd60 net/core/net_namespace.c:652 > > process_one_work kernel/workqueue.c:3236 [inline] > > process_scheduled_works+0xa66/0x1840 kernel/workqueue.c:3317 > > worker_thread+0x870/0xd30 kernel/workqueue.c:3398 > > kthread+0x2f0/0x390 kernel/kthread.c:389 > > ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 > > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > > </TASK> > > hsr_slave_0: left promiscuous mode > > hsr_slave_1: left promiscuous mode > > batman_adv: batadv0: Interface deactivated: batadv_slave_0 > > batman_adv: batadv0: Removing interface: batadv_slave_0 > > batman_adv: batadv0: Interface deactivated: batadv_slave_1 > > batman_adv: batadv0: Removing interface: batadv_slave_1 > > veth1_macvtap: left promiscuous mode > > veth0_macvtap: left promiscuous mode > > veth1_vlan: left promiscuous mode > > veth0_vlan: left promiscuous mode > > team0 (unregistering): Port device team_slave_1 removed > > team0 (unregistering): Port device team_slave_0 removed > > bridge0: port 2(bridge_slave_1) entered blocking state > > bridge0: port 2(bridge_slave_1) entered forwarding state > > bridge0: port 1(bridge_slave_0) entered blocking state > > bridge0: port 1(bridge_slave_0) entered forwarding state > > bridge0: port 2(bridge_slave_1) entered blocking state > > bridge0: port 2(bridge_slave_1) entered forwarding state > > > > > > --- > > If you want syzbot to run the reproducer, reply with: > > #syz test: git://repo/address.git branch-or-commit-hash > > If you attach or paste a git patch, syzbot will apply it before testing. > > This repro is for another bug I think, caused by my recent commits in net-next: > > 83419b61d187ce22aa3da5ffdda850fca3a12600 net: reduce RTNL hold > duration in unregister_netdevice_many_notify() (part 2) > ae646f1a0bb97401bac0044bbe2a179a1e38b408 net: reduce RTNL hold > duration in unregister_netdevice_many_notify() (part 1) > cfa579f6665635b72d4a075fc91eb144c2b0f74e net: no longer hold RTNL > while calling flush_all_backlogs() > > cleanup_net() > rtnl_lock(); > mutex_lock(subsystem_mutex); > > unregister_netdevice(); > > rtnl_unlock(); // LOCKDEP violation > rtnl_lock(); > > I will work today on a fix, auditing all unregister_netdevice() and > unregister_netdevice_many() > and select which of them can safely opt-in for a variant which _can_ > temporarily release RTNL. > Could you please share what's the current situation with the fix? The bug unfortunately keeps on stalling the fuzzing on syzbot by causing 70+% of all daily crashes. -- Aleksandr
