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List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a92:ca4f:0:b0:3d0:24c0:bd4d with SMTP id e9e14a558f8ab-3d024c0bfafmr57473895ab.18.1738522586968; Sun, 02 Feb 2025 10:56:26 -0800 (PST) Date: Sun, 02 Feb 2025 10:56:26 -0800 In-Reply-To: <000000000000931657061ffc8ad9@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <679fbfda.050a0220.d7c5a.0076.GAE@google.com> Subject: Re: [syzbot] [kernfs?] possible deadlock in walk_component (4) From: syzbot To: gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, tj@kernel.org Content-Type: text/plain; charset="UTF-8" syzbot has found a reproducer for the following issue on: HEAD commit: 69e858e0b8b2 Merge tag 'uml-for-linus-6.14-rc1' of git://g.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=10dc6d18580000 kernel config: https://syzkaller.appspot.com/x/.config?x=98d83cc1742b7377 dashboard link: https://syzkaller.appspot.com/bug?extid=b4567a8b2d2ad5f9dd06 compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=116fceb0580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15bf03df980000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/3d07b0558b0e/disk-69e858e0.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/e5e2250eb3b1/vmlinux-69e858e0.xz kernel image: https://storage.googleapis.com/syzbot-assets/3e676d17effc/bzImage-69e858e0.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+b4567a8b2d2ad5f9dd06@syzkaller.appspotmail.com ====================================================== WARNING: possible circular locking dependency detected 6.13.0-syzkaller-09760-g69e858e0b8b2 #0 Not tainted ------------------------------------------------------ syz-executor466/5830 is trying to acquire lock: ffff88807997f398 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: inode_lock_shared include/linux/fs.h:875 [inline] ffff88807997f398 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: lookup_slow fs/namei.c:1809 [inline] ffff88807997f398 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: walk_component+0x342/0x5b0 fs/namei.c:2114 but task is already holding lock: ffffffff8e07d228 (param_lock){+.+.}-{4:4}, at: kernel_param_lock kernel/params.c:607 [inline] ffffffff8e07d228 (param_lock){+.+.}-{4:4}, at: param_attr_store+0xe6/0x300 kernel/params.c:586 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (param_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0x19b/0xb10 kernel/locking/mutex.c:730 ieee80211_rate_control_ops_get net/mac80211/rate.c:220 [inline] rate_control_alloc net/mac80211/rate.c:266 [inline] ieee80211_init_rate_ctrl_alg+0x18d/0x6b0 net/mac80211/rate.c:1015 ieee80211_register_hw+0x2077/0x3ff0 net/mac80211/main.c:1531 mac80211_hwsim_new_radio+0x2c47/0x56d0 drivers/net/wireless/virtual/mac80211_hwsim.c:5558 init_mac80211_hwsim+0x432/0x8c0 drivers/net/wireless/virtual/mac80211_hwsim.c:6910 do_one_initcall+0x128/0x630 init/main.c:1257 do_initcall_level init/main.c:1319 [inline] do_initcalls init/main.c:1335 [inline] do_basic_setup init/main.c:1354 [inline] kernel_init_freeable+0x58f/0x8b0 init/main.c:1568 kernel_init+0x1c/0x2b0 init/main.c:1457 ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:148 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 -> #2 (rtnl_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0x19b/0xb10 kernel/locking/mutex.c:730 cgrp_css_online+0xa9/0x200 net/core/netprio_cgroup.c:157 online_css+0xaf/0x350 kernel/cgroup/cgroup.c:5568 css_create kernel/cgroup/cgroup.c:5652 [inline] cgroup_apply_control_enable+0x6d7/0xc80 kernel/cgroup/cgroup.c:3239 cgroup_mkdir+0x398/0x1150 kernel/cgroup/cgroup.c:5847 kernfs_iop_mkdir+0x14a/0x1d0 fs/kernfs/dir.c:1247 vfs_mkdir+0x57d/0x860 fs/namei.c:4313 do_mkdirat+0x301/0x3a0 fs/namei.c:4336 __do_sys_mkdir fs/namei.c:4356 [inline] __se_sys_mkdir fs/namei.c:4354 [inline] __x64_sys_mkdir+0xef/0x140 fs/namei.c:4354 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (cgroup_mutex){+.+.}-{4:4}: __mutex_lock_common kernel/locking/mutex.c:585 [inline] __mutex_lock+0x19b/0xb10 kernel/locking/mutex.c:730 cgroup_lock include/linux/cgroup.h:368 [inline] cgroup_kn_lock_live+0x139/0x570 kernel/cgroup/cgroup.c:1662 cgroup_rmdir+0x22/0x2d0 kernel/cgroup/cgroup.c:6045 kernfs_iop_rmdir+0x143/0x1c0 fs/kernfs/dir.c:1265 vfs_rmdir fs/namei.c:4396 [inline] vfs_rmdir+0x203/0x690 fs/namei.c:4373 do_rmdir+0x3a2/0x410 fs/namei.c:4455 __do_sys_rmdir fs/namei.c:4474 [inline] __se_sys_rmdir fs/namei.c:4472 [inline] __x64_sys_rmdir+0xc5/0x110 fs/namei.c:4472 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&type->i_mutex_dir_key#6){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3163 [inline] check_prevs_add kernel/locking/lockdep.c:3282 [inline] validate_chain kernel/locking/lockdep.c:3906 [inline] __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5228 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5851 down_read+0x9a/0x330 kernel/locking/rwsem.c:1524 inode_lock_shared include/linux/fs.h:875 [inline] lookup_slow fs/namei.c:1809 [inline] walk_component+0x342/0x5b0 fs/namei.c:2114 lookup_last fs/namei.c:2612 [inline] path_lookupat+0x17f/0x770 fs/namei.c:2636 filename_lookup+0x221/0x5f0 fs/namei.c:2665 kern_path+0x35/0x50 fs/namei.c:2773 lookup_bdev+0xd9/0x280 block/bdev.c:1163 bdev_file_open_by_path+0x83/0x330 block/bdev.c:1036 add_device drivers/mtd/devices/block2mtd.c:279 [inline] block2mtd_setup2+0x32e/0xe30 drivers/mtd/devices/block2mtd.c:459 block2mtd_setup+0x55/0x70 drivers/mtd/devices/block2mtd.c:476 param_attr_store+0x18f/0x300 kernel/params.c:588 module_attr_store+0x55/0x80 kernel/params.c:924 sysfs_kf_write+0x117/0x170 fs/sysfs/file.c:139 kernfs_fop_write_iter+0x33d/0x500 fs/kernfs/file.c:334 new_sync_write fs/read_write.c:586 [inline] vfs_write+0x5ae/0x1150 fs/read_write.c:679 ksys_write+0x12b/0x250 fs/read_write.c:731 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: &type->i_mutex_dir_key#6 --> rtnl_mutex --> param_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(param_lock); lock(rtnl_mutex); lock(param_lock); rlock(&type->i_mutex_dir_key#6); *** DEADLOCK *** 4 locks held by syz-executor466/5830: #0: ffff8880244b2420 (sb_writers#8){.+.+}-{0:0}, at: ksys_write+0x12b/0x250 fs/read_write.c:731 #1: ffff88802975f488 (&of->mutex){+.+.}-{4:4}, at: kernfs_fop_write_iter+0x27b/0x500 fs/kernfs/file.c:325 #2: ffff88814c9e6008 (kn->active#4){.+.+}-{0:0}, at: kernfs_fop_write_iter+0x29e/0x500 fs/kernfs/file.c:326 #3: ffffffff8e07d228 (param_lock){+.+.}-{4:4}, at: kernel_param_lock kernel/params.c:607 [inline] #3: ffffffff8e07d228 (param_lock){+.+.}-{4:4}, at: param_attr_store+0xe6/0x300 kernel/params.c:586 stack backtrace: CPU: 0 UID: 0 PID: 5830 Comm: syz-executor466 Not tainted 6.13.0-syzkaller-09760-g69e858e0b8b2 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_circular_bug+0x490/0x760 kernel/locking/lockdep.c:2076 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2208 check_prev_add kernel/locking/lockdep.c:3163 [inline] check_prevs_add kernel/locking/lockdep.c:3282 [inline] validate_chain kernel/locking/lockdep.c:3906 [inline] __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5228 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5851 down_read+0x9a/0x330 kernel/locking/rwsem.c:1524 inode_lock_shared include/linux/fs.h:875 [inline] lookup_slow fs/namei.c:1809 [inline] walk_component+0x342/0x5b0 fs/namei.c:2114 lookup_last fs/namei.c:2612 [inline] path_lookupat+0x17f/0x770 fs/namei.c:2636 filename_lookup+0x221/0x5f0 fs/namei.c:2665 kern_path+0x35/0x50 fs/namei.c:2773 lookup_bdev+0xd9/0x280 block/bdev.c:1163 bdev_file_open_by_path+0x83/0x330 block/bdev.c:1036 add_device drivers/mtd/devices/block2mtd.c:279 [inline] block2mtd_setup2+0x32e/0xe30 drivers/mtd/devices/block2mtd.c:459 block2mtd_setup+0x55/0x70 drivers/mtd/devices/block2mtd.c:476 param_attr_store+0x18f/0x300 kernel/params.c:588 module_attr_store+0x55/0x80 kernel/params.c:924 sysfs_kf_write+0x117/0x170 fs/sysfs/file.c:139 kernfs_fop_write_iter+0x33d/0x500 fs/kernfs/file.c:334 new_sync_write fs/read_write.c:586 [inline] vfs_write+0x5ae/0x1150 fs/read_write.c:679 ksys_write+0x12b/0x250 fs/read_write.c:731 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f64e4ab2ea9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 18 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 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fffc0a6c6d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f64e4ab2ea9 RDX: 0000000000000003 RSI: 0000000020000000 RDI: 0000000000000003 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f64e4afc036 R13: 00007fffc0a6c710 R14: 00007fffc0a6c750 R15: 0000000000000000 block2mtd: error: cannot open device 3QI --- 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.