On Tue, Feb 13, 2024 at 07:41:50PM +0800, Hillf Danton wrote: > On Mon, 12 Feb 2024 23:12:22 -0800 > > HEAD commit: 716f4aaa7b48 Merge tag 'vfs-6.8-rc5.fixes' of git://git.ke.. > > git tree: upstream > > console+strace: https://syzkaller.appspot.com/x/log.txt?x=100fd062180000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=1d7c92dd8d5c7a1e > > dashboard link: https://syzkaller.appspot.com/bug?extid=c2ada45c23d98d646118 > > 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=11fcbd48180000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17f6e642180000 > > > > Downloadable assets: > > disk image: https://storage.googleapis.com/syzbot-assets/ca4bf59e5a18/disk-716f4aaa.raw.xz > > vmlinux: https://storage.googleapis.com/syzbot-assets/3d7ade517e63/vmlinux-716f4aaa.xz > > kernel image: https://storage.googleapis.com/syzbot-assets/e13f7054c0c1/bzImage-716f4aaa.xz > > mounted in repro: https://storage.googleapis.com/syzbot-assets/00ba9c2f3dd0/mount_0.gz > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+c2ada45c23d98d646118@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > loop0: detected capacity change from 0 to 4096 > > ntfs3: loop0: Different NTFS sector size (4096) and media sector size (512). > > ntfs3: loop0: ino=5, "/" ntfs_iget5 > > ============================================ > > WARNING: possible recursive locking detected > > 6.8.0-rc4-syzkaller-00003-g716f4aaa7b48 #0 Not tainted > > -------------------------------------------- > > syz-executor354/5071 is trying to acquire lock: > > ffff888070ee0100 (&ni->ni_lock#3){+.+.}-{3:3}, at: ntfs_set_state+0x1ff/0x6c0 fs/ntfs3/fsntfs.c:947 this is a mutex_lock_nested() with a subkey 0. > > > > but task is already holding lock: > > ffff888070de3c00 (&ni->ni_lock#3){+.+.}-{3:3}, at: ni_trylock fs/ntfs3/ntfs_fs.h:1141 [inline] > > ffff888070de3c00 (&ni->ni_lock#3){+.+.}-{3:3}, at: ni_write_inode+0x1bc/0x1010 fs/ntfs3/frecord.c:3265 These two are try locks. > > > This report looks false positive but raises the question -- what made lockedp This is not a false positive by lockdep locking rules, basically it reported deadlock cases as the follow: mutex_trylock(A1); mutex_trylock(A2); mutex_lock(A1 /* or A2 */); Two things to notice here: 1) these two trylock()s not resulting in real deadlock cases must be because they are on different lock instances, 2) deadlock detectors work on lock classes, so although the mutex_lock() above may be on a different instance (say A3), currently there is no way for lockdep to tell that. In this case, users need to use subkeys to tell lockdep mutex_lock() and mutex_trylock() are on different sets of instannces (i.e. sub classes). Note that subkey == 0 means the main class. Regards, Boqun > pull the wrong trigger? Because of the correct lock_class_key in mutex_init() > instead of &ni->ni_lock? > > > other info that might help us debug this: > > Possible unsafe locking scenario: > > > > CPU0 > > ---- > > lock(&ni->ni_lock#3); > > lock(&ni->ni_lock#3); > > > > *** DEADLOCK *** > > > > May be due to missing lock nesting notation > > > > 3 locks held by syz-executor354/5071: > > #0: ffff88802223a420 (sb_writers#9){.+.+}-{0:0}, at: do_sys_ftruncate+0x25c/0x390 fs/open.c:191 > > #1: ffff888070de3ea0 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:802 [inline] > > #1: ffff888070de3ea0 (&sb->s_type->i_mutex_key#15){+.+.}-{3:3}, at: do_truncate+0x20c/0x310 fs/open.c:64 > > #2: ffff888070de3c00 (&ni->ni_lock#3){+.+.}-{3:3}, at: ni_trylock fs/ntfs3/ntfs_fs.h:1141 [inline] > > #2: ffff888070de3c00 (&ni->ni_lock#3){+.+.}-{3:3}, at: ni_write_inode+0x1bc/0x1010 fs/ntfs3/frecord.c:3265 > > > > stack backtrace: > > CPU: 0 PID: 5071 Comm: syz-executor354 Not tainted 6.8.0-rc4-syzkaller-00003-g716f4aaa7b48 #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024 > > Call Trace: > > <TASK> > > __dump_stack lib/dump_stack.c:88 [inline] > > dump_stack_lvl+0x1e7/0x2e0 lib/dump_stack.c:106 > > check_deadlock kernel/locking/lockdep.c:3062 [inline] > > validate_chain+0x15c0/0x58e0 kernel/locking/lockdep.c:3856 > > __lock_acquire+0x1345/0x1fd0 kernel/locking/lockdep.c:5137 > > lock_acquire+0x1e3/0x530 kernel/locking/lockdep.c:5754 > > __mutex_lock_common kernel/locking/mutex.c:608 [inline] > > __mutex_lock+0x136/0xd70 kernel/locking/mutex.c:752 > > ntfs_set_state+0x1ff/0x6c0 fs/ntfs3/fsntfs.c:947 > > ntfs_iget5+0x3f0/0x3b70 fs/ntfs3/inode.c:535 > > ni_update_parent+0x943/0xdd0 fs/ntfs3/frecord.c:3218 > > ni_write_inode+0xde9/0x1010 fs/ntfs3/frecord.c:3324 > > ntfs_truncate fs/ntfs3/file.c:410 [inline] > > ntfs3_setattr+0x950/0xb40 fs/ntfs3/file.c:703 > > notify_change+0xb9f/0xe70 fs/attr.c:499 > > do_truncate+0x220/0x310 fs/open.c:66 > > do_sys_ftruncate+0x2f7/0x390 fs/open.c:194 > > do_syscall_64+0xfb/0x240 > > entry_SYSCALL_64_after_hwframe+0x6f/0x77 > > RIP: 0033:0x7fd0ca446639 > > Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 17 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:00007fff0baab678 EFLAGS: 00000246 ORIG_RAX: 000000000000004d > > RAX: ffffffffffffffda RBX: 00007fff0baab848 RCX: 00007fd0ca446639 > > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004 > > RBP: 00007fd0ca4d8610 R08: 0000000000000000 R09: 00007fff0baab848 > > R10: 000000000001f20a R11: 0000000000000246 R12: 0000000000000001 > > R13: 00007fff0baab838 R14: 0000000000000001 R15: 0000000000000001 > > </TASK> > > > > > > --- > > This report is generated by a bot. It may contain errors. > > See https://goo.gl/tpsmEJ for more information about syzbot. > > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > > > syzbot will keep track of this issue. See: > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > > > If the report is already addressed, let syzbot know by replying with: > > #syz fix: exact-commit-title > > > > 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. > > > > If you want to overwrite report's subsystems, reply with: > > #syz set subsystems: new-subsystem > > (See the list of subsystem names on the web dashboard) > > > > If the report is a duplicate of another one, reply with: > > #syz dup: exact-subject-of-another-report > > > > If you want to undo deduplication, reply with: > > #syz undup > >
