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AJvYcCVpbj+Ere81Yxy10cba4efScaRe1SEDERWc7eqtNBCPn3P1g7QK3DIVgbTfoxmmCYo4GtKRZJcaUUOGtrP0@vger.kernel.org X-Gm-Message-State: AOJu0YzSnvk1ynklRervTxj494Cp99p0Oen0fPxnb85trs9XeYOVWoKN CQwjpAh54JL/Qkr99Sn3lNV8Bv+d+yFkWon5S4RoTmlJIEv+P6YfhMXwun+5JNK49c/0NgxKvUO m/1kuq7YHsBfjv9FSaYRDDedaE4GsihUGMz1ZjqmwqL//5QB02AfMQpJhxlQ= Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:4df9:b0:662:c0e5:b70 with SMTP id 006d021491bc7-662c0e50de5mr86282eaf.14.1769008742352; Wed, 21 Jan 2026 07:19:02 -0800 (PST) Date: Wed, 21 Jan 2026 07:19:02 -0800 In-Reply-To: <20260121150211.82216-1-activprithvi@gmail.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6970ee66.050a0220.706b.0011.GAE@google.com> Subject: Re: [syzbot] [fs?] possible deadlock in __configfs_open_file From: syzbot To: activprithvi@gmail.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot has tested the proposed patch but the reproducer is still triggering an issue: possible deadlock in __configfs_open_file ============================================ WARNING: possible recursive locking detected syzkaller #0 Not tainted -------------------------------------------- syz.0.17/6433 is trying to acquire lock: ffff888027868d78 (&p->frag_sem_key){.+.+}-{4:4}, at: __configfs_open_file+0xe8/0x9c0 fs/configfs/file.c:304 but task is already holding lock: ffff888027868d78 (&p->frag_sem_key){.+.+}-{4:4}, at: flush_write_buffer fs/configfs/file.c:205 [inline] ffff888027868d78 (&p->frag_sem_key){.+.+}-{4:4}, at: configfs_write_iter+0x219/0x4e0 fs/configfs/file.c:229 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&p->frag_sem_key); lock(&p->frag_sem_key); *** DEADLOCK *** May be due to missing lock nesting notation 5 locks held by syz.0.17/6433: #0: ffff888063464478 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x2a2/0x370 fs/file.c:1232 #1: ffff88801efbc420 (sb_writers#12){.+.+}-{0:0}, at: ksys_write+0x12a/0x250 fs/read_write.c:738 #2: ffff8880760ba888 (&buffer->mutex){+.+.}-{4:4}, at: configfs_write_iter+0x75/0x4e0 fs/configfs/file.c:226 #3: ffff888027868d78 (&p->frag_sem_key){.+.+}-{4:4}, at: flush_write_buffer fs/configfs/file.c:205 [inline] #3: ffff888027868d78 (&p->frag_sem_key){.+.+}-{4:4}, at: configfs_write_iter+0x219/0x4e0 fs/configfs/file.c:229 #4: ffffffff8f409828 (target_devices_lock){+.+.}-{4:4}, at: target_core_item_dbroot_store+0x21/0x350 drivers/target/target_core_configfs.c:114 stack backtrace: CPU: 0 UID: 0 PID: 6433 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/13/2026 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_deadlock_bug+0x1e9/0x240 kernel/locking/lockdep.c:3041 check_deadlock kernel/locking/lockdep.c:3093 [inline] validate_chain kernel/locking/lockdep.c:3895 [inline] __lock_acquire+0x1106/0x1c90 kernel/locking/lockdep.c:5237 lock_acquire kernel/locking/lockdep.c:5868 [inline] lock_acquire+0x179/0x350 kernel/locking/lockdep.c:5825 down_read+0x9b/0x480 kernel/locking/rwsem.c:1537 __configfs_open_file+0xe8/0x9c0 fs/configfs/file.c:304 do_dentry_open+0x982/0x1530 fs/open.c:965 vfs_open+0x82/0x3f0 fs/open.c:1097 do_open fs/namei.c:3975 [inline] path_openat+0x1de4/0x2cb0 fs/namei.c:4134 do_filp_open+0x20b/0x470 fs/namei.c:4161 file_open_name+0x2a3/0x450 fs/open.c:1381 filp_open+0x4b/0x80 fs/open.c:1401 target_core_item_dbroot_store+0x108/0x350 drivers/target/target_core_configfs.c:134 flush_write_buffer fs/configfs/file.c:207 [inline] configfs_write_iter+0x306/0x4e0 fs/configfs/file.c:229 new_sync_write fs/read_write.c:593 [inline] vfs_write+0x7d3/0x11d0 fs/read_write.c:686 ksys_write+0x12a/0x250 fs/read_write.c:738 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0xfa0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fd76878eec9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fd7696dd038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00007fd7689e5fa0 RCX: 00007fd76878eec9 RDX: 0000000000000fff RSI: 0000200000000000 RDI: 0000000000000003 RBP: 00007fd768811f91 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fd7689e6038 R14: 00007fd7689e5fa0 R15: 00007ffe6bade968 db_root: not a directory: /sys/kernel/config/target/dbroot Tested on: commit: 3a866087 Linux 6.18-rc1 git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git console output: https://syzkaller.appspot.com/x/log.txt?x=14c307fc580000 kernel config: https://syzkaller.appspot.com/x/.config?x=e854293d7f44b5a5 dashboard link: https://syzkaller.appspot.com/bug?extid=f6e8174215573a84b797 compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 patch: https://syzkaller.appspot.com/x/patch.diff?x=17d7979a580000