On Sat, May 18, 2024 at 9:29 PM syzbot <syzbot+77c39f023a0cb2e4c149@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit: a5131c3fdf26 Merge tag 'x86-shstk-2024-05-13' of git://git.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=144c6e04980000 > kernel config: https://syzkaller.appspot.com/x/.config?x=fdb182f40cdd66f7 > dashboard link: https://syzkaller.appspot.com/bug?extid=77c39f023a0cb2e4c149 > compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 > userspace arch: i386 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-a5131c3f.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/6d23116dab9c/vmlinux-a5131c3f.xz > kernel image: https://storage.googleapis.com/syzbot-assets/dd8b9de9af4f/bzImage-a5131c3f.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+77c39f023a0cb2e4c149@xxxxxxxxxxxxxxxxxxxxxxxxx > > NILFS (loop2): inode bitmap is inconsistent for reserved inodes > NILFS (loop2): repaired inode bitmap for reserved inodes > ====================================================== > WARNING: possible circular locking dependency detected > 6.9.0-syzkaller-01768-ga5131c3fdf26 #0 Not tainted > ------------------------------------------------------ > syz-executor.2/23478 is trying to acquire lock: > ffffffff8d938460 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:312 [inline] > ffffffff8d938460 (fs_reclaim){+.+.}-{0:0}, at: prepare_alloc_pages.constprop.0+0x155/0x560 mm/page_alloc.c:4346 > > but task is already holding lock: > ffff888026c5c2a0 (&nilfs->ns_segctor_sem){++++}-{3:3}, at: nilfs_transaction_begin+0x326/0xa40 fs/nilfs2/segment.c:223 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #2 (&nilfs->ns_segctor_sem){++++}-{3:3}: > down_read+0x9a/0x330 kernel/locking/rwsem.c:1526 > nilfs_transaction_begin+0x326/0xa40 fs/nilfs2/segment.c:223 > nilfs_create+0xb7/0x320 fs/nilfs2/namei.c:82 > lookup_open.isra.0+0x10a1/0x13c0 fs/namei.c:3505 > open_last_lookups fs/namei.c:3574 [inline] > path_openat+0x92f/0x2990 fs/namei.c:3804 > do_filp_open+0x1dc/0x430 fs/namei.c:3834 > do_sys_openat2+0x17a/0x1e0 fs/open.c:1406 > do_sys_open fs/open.c:1421 [inline] > __do_compat_sys_openat fs/open.c:1481 [inline] > __se_compat_sys_openat fs/open.c:1479 [inline] > __ia32_compat_sys_openat+0x16e/0x210 fs/open.c:1479 > do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] > __do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:386 > do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 > entry_SYSENTER_compat_after_hwframe+0x84/0x8e > > -> #1 (sb_internal#5){.+.+}-{0:0}: > percpu_down_read include/linux/percpu-rwsem.h:51 [inline] > __sb_start_write include/linux/fs.h:1661 [inline] > sb_start_intwrite include/linux/fs.h:1844 [inline] > nilfs_transaction_begin+0x21b/0xa40 fs/nilfs2/segment.c:220 > nilfs_dirty_inode+0x1a4/0x270 fs/nilfs2/inode.c:1153 > __mark_inode_dirty+0x1f0/0xe70 fs/fs-writeback.c:2486 > mark_inode_dirty_sync include/linux/fs.h:2426 [inline] > iput.part.0+0x5b/0x7f0 fs/inode.c:1764 > iput+0x5c/0x80 fs/inode.c:1757 > dentry_unlink_inode+0x295/0x440 fs/dcache.c:400 > __dentry_kill+0x1d0/0x600 fs/dcache.c:603 > shrink_kill fs/dcache.c:1048 [inline] > shrink_dentry_list+0x140/0x5d0 fs/dcache.c:1075 > prune_dcache_sb+0xeb/0x150 fs/dcache.c:1156 > super_cache_scan+0x32a/0x550 fs/super.c:221 > do_shrink_slab+0x44f/0x11c0 mm/shrinker.c:435 > shrink_slab_memcg mm/shrinker.c:548 [inline] > shrink_slab+0xa87/0x1310 mm/shrinker.c:626 > shrink_one+0x493/0x7c0 mm/vmscan.c:4774 > shrink_many mm/vmscan.c:4835 [inline] > lru_gen_shrink_node+0x89f/0x1750 mm/vmscan.c:4935 > shrink_node mm/vmscan.c:5894 [inline] > kswapd_shrink_node mm/vmscan.c:6704 [inline] > balance_pgdat+0x10d1/0x1a10 mm/vmscan.c:6895 > kswapd+0x5ea/0xbf0 mm/vmscan.c:7164 > kthread+0x2c1/0x3a0 kernel/kthread.c:388 > ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147 > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 > > -> #0 (fs_reclaim){+.+.}-{0:0}: > check_prev_add kernel/locking/lockdep.c:3134 [inline] > check_prevs_add kernel/locking/lockdep.c:3253 [inline] > validate_chain kernel/locking/lockdep.c:3869 [inline] > __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137 > lock_acquire kernel/locking/lockdep.c:5754 [inline] > lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719 > __fs_reclaim_acquire mm/page_alloc.c:3698 [inline] > fs_reclaim_acquire+0x102/0x160 mm/page_alloc.c:3712 > might_alloc include/linux/sched/mm.h:312 [inline] > prepare_alloc_pages.constprop.0+0x155/0x560 mm/page_alloc.c:4346 > __alloc_pages+0x194/0x2460 mm/page_alloc.c:4564 > alloc_pages_mpol+0x275/0x610 mm/mempolicy.c:2264 > folio_alloc+0x1e/0x40 mm/mempolicy.c:2342 > filemap_alloc_folio+0x3ba/0x490 mm/filemap.c:984 > __filemap_get_folio+0x527/0xa90 mm/filemap.c:1926 > pagecache_get_page+0x2c/0x260 mm/folio-compat.c:93 > block_write_begin+0x38/0x4a0 fs/buffer.c:2209 > nilfs_write_begin+0x9f/0x1a0 fs/nilfs2/inode.c:262 > page_symlink+0x356/0x450 fs/namei.c:5236 > nilfs_symlink+0x23c/0x3c0 fs/nilfs2/namei.c:153 > vfs_symlink fs/namei.c:4489 [inline] > vfs_symlink+0x3e8/0x630 fs/namei.c:4473 > do_symlinkat+0x263/0x310 fs/namei.c:4515 > __do_sys_symlink fs/namei.c:4536 [inline] > __se_sys_symlink fs/namei.c:4534 [inline] > __ia32_sys_symlink+0x78/0xa0 fs/namei.c:4534 > do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] > __do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:386 > do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 > entry_SYSENTER_compat_after_hwframe+0x84/0x8e > > other info that might help us debug this: > > Chain exists of: > fs_reclaim --> sb_internal#5 --> &nilfs->ns_segctor_sem > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > rlock(&nilfs->ns_segctor_sem); > lock(sb_internal#5); > lock(&nilfs->ns_segctor_sem); > lock(fs_reclaim); > > *** DEADLOCK *** > > 4 locks held by syz-executor.2/23478: > #0: ffff888000c0c420 (sb_writers#32){.+.+}-{0:0}, at: filename_create+0x10d/0x530 fs/namei.c:3893 > #1: ffff88804b284f88 (&type->i_mutex_dir_key#23/1){+.+.}-{3:3}, at: inode_lock_nested include/linux/fs.h:826 [inline] > #1: ffff88804b284f88 (&type->i_mutex_dir_key#23/1){+.+.}-{3:3}, at: filename_create+0x1c2/0x530 fs/namei.c:3900 > #2: ffff888000c0c610 (sb_internal#5){.+.+}-{0:0}, at: nilfs_symlink+0x114/0x3c0 fs/nilfs2/namei.c:140 > #3: ffff888026c5c2a0 (&nilfs->ns_segctor_sem){++++}-{3:3}, at: nilfs_transaction_begin+0x326/0xa40 fs/nilfs2/segment.c:223 > > stack backtrace: > CPU: 2 PID: 23478 Comm: syz-executor.2 Not tainted 6.9.0-syzkaller-01768-ga5131c3fdf26 #0 > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014 > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114 > check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2187 > check_prev_add kernel/locking/lockdep.c:3134 [inline] > check_prevs_add kernel/locking/lockdep.c:3253 [inline] > validate_chain kernel/locking/lockdep.c:3869 [inline] > __lock_acquire+0x2478/0x3b30 kernel/locking/lockdep.c:5137 > lock_acquire kernel/locking/lockdep.c:5754 [inline] > lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5719 > __fs_reclaim_acquire mm/page_alloc.c:3698 [inline] > fs_reclaim_acquire+0x102/0x160 mm/page_alloc.c:3712 > might_alloc include/linux/sched/mm.h:312 [inline] > prepare_alloc_pages.constprop.0+0x155/0x560 mm/page_alloc.c:4346 > __alloc_pages+0x194/0x2460 mm/page_alloc.c:4564 > alloc_pages_mpol+0x275/0x610 mm/mempolicy.c:2264 > folio_alloc+0x1e/0x40 mm/mempolicy.c:2342 > filemap_alloc_folio+0x3ba/0x490 mm/filemap.c:984 > __filemap_get_folio+0x527/0xa90 mm/filemap.c:1926 > pagecache_get_page+0x2c/0x260 mm/folio-compat.c:93 > block_write_begin+0x38/0x4a0 fs/buffer.c:2209 > nilfs_write_begin+0x9f/0x1a0 fs/nilfs2/inode.c:262 > page_symlink+0x356/0x450 fs/namei.c:5236 > nilfs_symlink+0x23c/0x3c0 fs/nilfs2/namei.c:153 > vfs_symlink fs/namei.c:4489 [inline] > vfs_symlink+0x3e8/0x630 fs/namei.c:4473 > do_symlinkat+0x263/0x310 fs/namei.c:4515 > __do_sys_symlink fs/namei.c:4536 [inline] > __se_sys_symlink fs/namei.c:4534 [inline] > __ia32_sys_symlink+0x78/0xa0 fs/namei.c:4534 > do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] > __do_fast_syscall_32+0x75/0x120 arch/x86/entry/common.c:386 > do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 > entry_SYSENTER_compat_after_hwframe+0x84/0x8e > RIP: 0023:0xf734f579 > Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 > RSP: 002b:00000000f5f415ac EFLAGS: 00000292 ORIG_RAX: 0000000000000053 > RAX: ffffffffffffffda RBX: 0000000020000340 RCX: 0000000020000100 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > </TASK> > ---------------- > Code disassembly (best guess), 2 bytes skipped: > 0: 10 06 adc %al,(%rsi) > 2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi > 6: 10 07 adc %al,(%rdi) > 8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi > c: 10 08 adc %cl,(%rax) > e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi > 1e: 00 51 52 add %dl,0x52(%rcx) > 21: 55 push %rbp > 22: 89 e5 mov %esp,%ebp > 24: 0f 34 sysenter > 26: cd 80 int $0x80 > * 28: 5d pop %rbp <-- trapping instruction > 29: 5a pop %rdx > 2a: 59 pop %rcx > 2b: c3 ret > 2c: 90 nop > 2d: 90 nop > 2e: 90 nop > 2f: 90 nop > 30: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi > 37: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi > > > --- > 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 This issue seems to be the same as the report below, but I don't have time to look into it in detail right now, so I'll put it on hold. https://syzkaller.appspot.com/bug?extid=ca73f5a22aec76875d85 It looks like the GFP flags in the symlink's page cache allocation are causing the circular lock dependency. Ryusuke Konishi
