On Wed, Apr 30, 2025 at 4:56 PM syzbot <syzbot+3f86ff971bc63d62b932@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: ca91b9500108 Merge tag 'v6.15-rc4-ksmbd-server-fixes' of g.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=175868d4580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=a42a9d552788177b > dashboard link: https://syzkaller.appspot.com/bug?extid=3f86ff971bc63d62b932 > compiler: Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/8f91302b28da/disk-ca91b950.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/99926b0845ed/vmlinux-ca91b950.xz > kernel image: https://storage.googleapis.com/syzbot-assets/ace62028a7c9/bzImage-ca91b950.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+3f86ff971bc63d62b932@xxxxxxxxxxxxxxxxxxxxxxxxx > > ====================================================== > WARNING: possible circular locking dependency detected > 6.15.0-rc4-syzkaller-00021-gca91b9500108 #0 Not tainted > ------------------------------------------------------ > syz.0.145/7282 is trying to acquire lock: > ffff88806be68610 (sb_internal#4){.+.+}-{0:0}, at: nilfs_page_mkwrite+0x8b0/0xc20 fs/nilfs2/file.c:95 > > but task is already holding lock: > ffff88806be68518 (sb_pagefaults#4){.+.+}-{0:0}, at: do_page_mkwrite+0x14a/0x310 mm/memory.c:3287 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #5 (sb_pagefaults#4){.+.+}-{0:0}: > lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 > percpu_down_read include/linux/percpu-rwsem.h:52 [inline] > __sb_start_write include/linux/fs.h:1783 [inline] > sb_start_pagefault include/linux/fs.h:1948 [inline] > nilfs_page_mkwrite+0x21e/0xc20 fs/nilfs2/file.c:57 > do_page_mkwrite+0x14a/0x310 mm/memory.c:3287 > do_shared_fault mm/memory.c:5594 [inline] > do_fault mm/memory.c:5656 [inline] > do_pte_missing mm/memory.c:4160 [inline] > handle_pte_fault mm/memory.c:5997 [inline] > __handle_mm_fault+0x18d2/0x5380 mm/memory.c:6140 > handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6309 > faultin_page mm/gup.c:1193 [inline] > __get_user_pages+0x16f0/0x2a40 mm/gup.c:1491 > __get_user_pages_locked mm/gup.c:1821 [inline] > __gup_longterm_locked+0x105d/0x15b0 mm/gup.c:2523 > gup_fast_fallback+0x1843/0x1d60 mm/gup.c:3417 > iov_iter_extract_user_pages lib/iov_iter.c:1849 [inline] > iov_iter_extract_pages+0x35a/0x5e0 lib/iov_iter.c:1912 > dio_refill_pages fs/direct-io.c:172 [inline] > dio_get_page fs/direct-io.c:213 [inline] > do_direct_IO fs/direct-io.c:915 [inline] > __blockdev_direct_IO+0x10ed/0x3310 fs/direct-io.c:1243 > blockdev_direct_IO include/linux/fs.h:3422 [inline] > nilfs_direct_IO+0xed/0x120 fs/nilfs2/inode.c:267 > generic_file_read_iter+0x319/0x510 mm/filemap.c:2871 > new_sync_read fs/read_write.c:489 [inline] > vfs_read+0x4cd/0x980 fs/read_write.c:570 > ksys_read+0x145/0x250 fs/read_write.c:713 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > -> #4 (&mm->mmap_lock){++++}-{4:4}: > lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 > __might_fault+0xcc/0x130 mm/memory.c:7151 > _copy_to_iter+0xf3/0x15a0 lib/iov_iter.c:184 > copy_page_to_iter+0xa7/0x150 lib/iov_iter.c:362 > copy_folio_to_iter include/linux/uio.h:198 [inline] > filemap_read+0x78d/0x11d0 mm/filemap.c:2753 > blkdev_read_iter+0x30a/0x440 block/fops.c:809 > new_sync_read fs/read_write.c:489 [inline] > vfs_read+0x4cd/0x980 fs/read_write.c:570 > ksys_read+0x145/0x250 fs/read_write.c:713 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > -> #3 (&sb->s_type->i_mutex_key#7){++++}-{4:4}: > lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 > down_write+0x96/0x1f0 kernel/locking/rwsem.c:1577 > inode_lock include/linux/fs.h:867 [inline] > set_blocksize+0x23b/0x500 block/bdev.c:203 > sb_set_blocksize block/bdev.c:224 [inline] > sb_min_blocksize+0x119/0x210 block/bdev.c:239 > init_nilfs+0x43/0x690 fs/nilfs2/the_nilfs.c:710 > nilfs_fill_super+0x8f/0x650 fs/nilfs2/super.c:1060 > nilfs_get_tree+0x4f4/0x870 fs/nilfs2/super.c:1228 > vfs_get_tree+0x8f/0x2b0 fs/super.c:1759 > do_new_mount+0x24a/0xa40 fs/namespace.c:3884 > do_mount fs/namespace.c:4224 [inline] > __do_sys_mount fs/namespace.c:4435 [inline] > __se_sys_mount+0x317/0x410 fs/namespace.c:4412 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > -> #2 (&nilfs->ns_sem){++++}-{4:4}: > lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 > down_write+0x96/0x1f0 kernel/locking/rwsem.c:1577 > nilfs_set_error fs/nilfs2/super.c:92 [inline] > __nilfs_error+0x1ca/0x4b0 fs/nilfs2/super.c:141 > nilfs_bmap_convert_error fs/nilfs2/bmap.c:35 [inline] > nilfs_bmap_propagate+0x108/0x130 fs/nilfs2/bmap.c:332 > nilfs_collect_file_data+0x4f/0xd0 fs/nilfs2/segment.c:589 > nilfs_segctor_apply_buffers+0x161/0x330 fs/nilfs2/segment.c:1010 > nilfs_segctor_scan_file+0x68e/0x8e0 fs/nilfs2/segment.c:1059 > nilfs_segctor_collect_blocks fs/nilfs2/segment.c:1254 [inline] > nilfs_segctor_collect fs/nilfs2/segment.c:1547 [inline] > nilfs_segctor_do_construct+0x1d46/0x6970 fs/nilfs2/segment.c:2122 > nilfs_segctor_construct+0x17b/0x690 fs/nilfs2/segment.c:2478 > nilfs_segctor_thread_construct fs/nilfs2/segment.c:2586 [inline] > nilfs_segctor_thread+0x6f7/0xe00 fs/nilfs2/segment.c:2700 > kthread+0x70e/0x8a0 kernel/kthread.c:464 > ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:153 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 > > -> #1 (&nilfs->ns_segctor_sem){++++}-{4:4}: > lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 > down_read+0x46/0x2e0 kernel/locking/rwsem.c:1524 > nilfs_transaction_begin+0x365/0x710 fs/nilfs2/segment.c:221 > nilfs_create+0xc9/0x2f0 fs/nilfs2/namei.c:95 > lookup_open fs/namei.c:3701 [inline] > open_last_lookups fs/namei.c:3800 [inline] > path_openat+0x14f1/0x3830 fs/namei.c:4036 > do_filp_open+0x1fa/0x410 fs/namei.c:4066 > do_sys_openat2+0x121/0x1c0 fs/open.c:1429 > do_sys_open fs/open.c:1444 [inline] > __do_sys_openat fs/open.c:1460 [inline] > __se_sys_openat fs/open.c:1455 [inline] > __x64_sys_openat+0x138/0x170 fs/open.c:1455 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > -> #0 (sb_internal#4){.+.+}-{0:0}: > check_prev_add kernel/locking/lockdep.c:3166 [inline] > check_prevs_add kernel/locking/lockdep.c:3285 [inline] > validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3909 > __lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235 > lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 > percpu_down_read include/linux/percpu-rwsem.h:52 [inline] > __sb_start_write include/linux/fs.h:1783 [inline] > sb_start_intwrite include/linux/fs.h:1966 [inline] > nilfs_transaction_begin+0x268/0x710 fs/nilfs2/segment.c:218 > nilfs_page_mkwrite+0x8b0/0xc20 fs/nilfs2/file.c:95 > do_page_mkwrite+0x14a/0x310 mm/memory.c:3287 > do_shared_fault mm/memory.c:5594 [inline] > do_fault mm/memory.c:5656 [inline] > do_pte_missing mm/memory.c:4160 [inline] > handle_pte_fault mm/memory.c:5997 [inline] > __handle_mm_fault+0x18d2/0x5380 mm/memory.c:6140 > handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6309 > faultin_page mm/gup.c:1193 [inline] > __get_user_pages+0x16f0/0x2a40 mm/gup.c:1491 > __get_user_pages_locked mm/gup.c:1821 [inline] > __gup_longterm_locked+0x105d/0x15b0 mm/gup.c:2523 > gup_fast_fallback+0x1843/0x1d60 mm/gup.c:3417 > iov_iter_extract_user_pages lib/iov_iter.c:1849 [inline] > iov_iter_extract_pages+0x35a/0x5e0 lib/iov_iter.c:1912 > dio_refill_pages fs/direct-io.c:172 [inline] > dio_get_page fs/direct-io.c:213 [inline] > do_direct_IO fs/direct-io.c:915 [inline] > __blockdev_direct_IO+0x10ed/0x3310 fs/direct-io.c:1243 > blockdev_direct_IO include/linux/fs.h:3422 [inline] > nilfs_direct_IO+0xed/0x120 fs/nilfs2/inode.c:267 > generic_file_read_iter+0x319/0x510 mm/filemap.c:2871 > new_sync_read fs/read_write.c:489 [inline] > vfs_read+0x4cd/0x980 fs/read_write.c:570 > ksys_read+0x145/0x250 fs/read_write.c:713 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > other info that might help us debug this: > > Chain exists of: > sb_internal#4 --> &mm->mmap_lock --> sb_pagefaults#4 > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > rlock(sb_pagefaults#4); > lock(&mm->mmap_lock); > lock(sb_pagefaults#4); > rlock(sb_internal#4); > > *** DEADLOCK *** > > 4 locks held by syz.0.145/7282: > #0: ffff8880258a0b78 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x247/0x320 fs/file.c:1213 > #1: ffff88805d73c8c0 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: inode_lock include/linux/fs.h:867 [inline] > #1: ffff88805d73c8c0 (&sb->s_type->i_mutex_key#23){+.+.}-{4:4}, at: __blockdev_direct_IO+0x318/0x3310 fs/direct-io.c:1140 > #2: ffff88806d6595e0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock_killable include/linux/mmap_lock.h:193 [inline] > #2: ffff88806d6595e0 (&mm->mmap_lock){++++}-{4:4}, at: __get_user_pages_locked mm/gup.c:1812 [inline] > #2: ffff88806d6595e0 (&mm->mmap_lock){++++}-{4:4}, at: __gup_longterm_locked+0x1005/0x15b0 mm/gup.c:2523 > #3: ffff88806be68518 (sb_pagefaults#4){.+.+}-{0:0}, at: do_page_mkwrite+0x14a/0x310 mm/memory.c:3287 > > stack backtrace: > CPU: 1 UID: 0 PID: 7282 Comm: syz.0.145 Not tainted 6.15.0-rc4-syzkaller-00021-gca91b9500108 #0 PREEMPT(full) > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025 > Call Trace: > <TASK> > dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 > print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2079 > check_noncircular+0x134/0x160 kernel/locking/lockdep.c:2211 > check_prev_add kernel/locking/lockdep.c:3166 [inline] > check_prevs_add kernel/locking/lockdep.c:3285 [inline] > validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3909 > __lock_acquire+0xaac/0xd20 kernel/locking/lockdep.c:5235 > lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5866 > percpu_down_read include/linux/percpu-rwsem.h:52 [inline] > __sb_start_write include/linux/fs.h:1783 [inline] > sb_start_intwrite include/linux/fs.h:1966 [inline] > nilfs_transaction_begin+0x268/0x710 fs/nilfs2/segment.c:218 > nilfs_page_mkwrite+0x8b0/0xc20 fs/nilfs2/file.c:95 > do_page_mkwrite+0x14a/0x310 mm/memory.c:3287 > do_shared_fault mm/memory.c:5594 [inline] > do_fault mm/memory.c:5656 [inline] > do_pte_missing mm/memory.c:4160 [inline] > handle_pte_fault mm/memory.c:5997 [inline] > __handle_mm_fault+0x18d2/0x5380 mm/memory.c:6140 > handle_mm_fault+0x2d5/0x7f0 mm/memory.c:6309 > faultin_page mm/gup.c:1193 [inline] > __get_user_pages+0x16f0/0x2a40 mm/gup.c:1491 > __get_user_pages_locked mm/gup.c:1821 [inline] > __gup_longterm_locked+0x105d/0x15b0 mm/gup.c:2523 > gup_fast_fallback+0x1843/0x1d60 mm/gup.c:3417 > iov_iter_extract_user_pages lib/iov_iter.c:1849 [inline] > iov_iter_extract_pages+0x35a/0x5e0 lib/iov_iter.c:1912 > dio_refill_pages fs/direct-io.c:172 [inline] > dio_get_page fs/direct-io.c:213 [inline] > do_direct_IO fs/direct-io.c:915 [inline] > __blockdev_direct_IO+0x10ed/0x3310 fs/direct-io.c:1243 > blockdev_direct_IO include/linux/fs.h:3422 [inline] > nilfs_direct_IO+0xed/0x120 fs/nilfs2/inode.c:267 > generic_file_read_iter+0x319/0x510 mm/filemap.c:2871 > new_sync_read fs/read_write.c:489 [inline] > vfs_read+0x4cd/0x980 fs/read_write.c:570 > ksys_read+0x145/0x250 fs/read_write.c:713 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7f75a3f8e969 > 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:00007f75a4de1038 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 > RAX: ffffffffffffffda RBX: 00007f75a41b6080 RCX: 00007f75a3f8e969 > RDX: 0000000000001000 RSI: 0000200000000400 RDI: 0000000000000004 > RBP: 00007f75a4010ab1 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > R13: 0000000000000001 R14: 00007f75a41b6080 R15: 00007fffacbb86c8 > </TASK> > NILFS error (device loop0): nilfs_bmap_lookup_contig: broken bmap (inode number=2097152) > Remounting filesystem read-only > > > --- > 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 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 Although syzbot has not found any reproducers yet, this looks a false positive deadlock warning, similar to the one in the syzbot report below, likely caused by inode locking introduced in set_blocksize(): #syz dup: possible deadlock in __nilfs_error (3) I am working on identifying the cause, and once that is done, I will submit a patch to resolve these issues with a fix to init_nilfs(). Ryusuke Konishi
