On Thu, Apr 25, 2024 at 07:46:28AM -0700, syzbot wrote: > Hello, > > syzbot found the following issue on: > > HEAD commit: 977b1ef51866 Merge tag 'block-6.9-20240420' of git://git.k.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=126497cd180000 > kernel config: https://syzkaller.appspot.com/x/.config?x=d239903bd07761e5 > dashboard link: https://syzkaller.appspot.com/bug?extid=b7e8d799f0ab724876f9 > compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/08d7b6e107aa/disk-977b1ef5.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/9c5e543ffdcf/vmlinux-977b1ef5.xz > kernel image: https://storage.googleapis.com/syzbot-assets/04a6d79d2f69/bzImage-977b1ef5.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+b7e8d799f0ab724876f9@xxxxxxxxxxxxxxxxxxxxxxxxx > > XFS (loop2): Ending clean mount > ====================================================== > WARNING: possible circular locking dependency detected > 6.9.0-rc4-syzkaller-00266-g977b1ef51866 #0 Not tainted > ------------------------------------------------------ > syz-executor.2/7915 is trying to acquire lock: > ffffffff8e42a800 (fs_reclaim){+.+.}-{0:0}, at: might_alloc include/linux/sched/mm.h:312 [inline] > ffffffff8e42a800 (fs_reclaim){+.+.}-{0:0}, at: slab_pre_alloc_hook mm/slub.c:3746 [inline] > ffffffff8e42a800 (fs_reclaim){+.+.}-{0:0}, at: slab_alloc_node mm/slub.c:3827 [inline] > ffffffff8e42a800 (fs_reclaim){+.+.}-{0:0}, at: kmalloc_trace+0x47/0x360 mm/slub.c:3992 > > but task is already holding lock: > ffff888056da8118 (&xfs_dir_ilock_class){++++}-{3:3}, at: xfs_ilock_data_map_shared+0x4f/0x70 fs/xfs/xfs_inode.c:114 > > which lock already depends on the new lock. > > > the existing dependency chain (in reverse order) is: > > -> #1 (&xfs_dir_ilock_class){++++}-{3:3}: > lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754 > down_write_nested+0x3d/0x50 kernel/locking/rwsem.c:1695 > xfs_reclaim_inode fs/xfs/xfs_icache.c:945 [inline] > xfs_icwalk_process_inode fs/xfs/xfs_icache.c:1631 [inline] > xfs_icwalk_ag+0x120e/0x1ad0 fs/xfs/xfs_icache.c:1713 > xfs_icwalk fs/xfs/xfs_icache.c:1762 [inline] > xfs_reclaim_inodes_nr+0x257/0x360 fs/xfs/xfs_icache.c:1011 > super_cache_scan+0x411/0x4b0 fs/super.c:227 > do_shrink_slab+0x707/0x1160 mm/shrinker.c:435 > shrink_slab+0x1092/0x14d0 mm/shrinker.c:662 > shrink_one+0x453/0x880 mm/vmscan.c:4774 > shrink_many mm/vmscan.c:4835 [inline] > lru_gen_shrink_node mm/vmscan.c:4935 [inline] > shrink_node+0x3b17/0x4310 mm/vmscan.c:5894 > kswapd_shrink_node mm/vmscan.c:6704 [inline] > balance_pgdat mm/vmscan.c:6895 [inline] > kswapd+0x1882/0x38a0 mm/vmscan.c:7164 > kthread+0x2f2/0x390 kernel/kthread.c:388 > ret_from_fork+0x4d/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+0x18cb/0x58e0 kernel/locking/lockdep.c:3869 > __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137 > lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754 > __fs_reclaim_acquire mm/page_alloc.c:3698 [inline] > fs_reclaim_acquire+0x88/0x140 mm/page_alloc.c:3712 > might_alloc include/linux/sched/mm.h:312 [inline] > slab_pre_alloc_hook mm/slub.c:3746 [inline] > slab_alloc_node mm/slub.c:3827 [inline] > kmalloc_trace+0x47/0x360 mm/slub.c:3992 > kmalloc include/linux/slab.h:628 [inline] > add_stack_record_to_list mm/page_owner.c:177 [inline] > inc_stack_record_count mm/page_owner.c:219 [inline] > __set_page_owner+0x561/0x810 mm/page_owner.c:334 > set_page_owner include/linux/page_owner.h:32 [inline] > post_alloc_hook+0x1ea/0x210 mm/page_alloc.c:1534 > prep_new_page mm/page_alloc.c:1541 [inline] > get_page_from_freelist+0x3410/0x35b0 mm/page_alloc.c:3317 > __alloc_pages+0x256/0x6c0 mm/page_alloc.c:4575 > __alloc_pages_bulk+0x729/0xd40 mm/page_alloc.c:4523 > alloc_pages_bulk_array include/linux/gfp.h:202 [inline] > xfs_buf_alloc_pages+0x1a7/0x860 fs/xfs/xfs_buf.c:398 > xfs_buf_find_insert+0x19a/0x1540 fs/xfs/xfs_buf.c:650 > xfs_buf_get_map+0x149c/0x1ae0 fs/xfs/xfs_buf.c:755 > xfs_buf_read_map+0x111/0xa60 fs/xfs/xfs_buf.c:860 > xfs_trans_read_buf_map+0x260/0xad0 fs/xfs/xfs_trans_buf.c:289 > xfs_da_read_buf+0x2b1/0x470 fs/xfs/libxfs/xfs_da_btree.c:2674 > xfs_dir3_block_read+0x92/0x1a0 fs/xfs/libxfs/xfs_dir2_block.c:145 > xfs_dir2_block_lookup_int+0x109/0x7d0 fs/xfs/libxfs/xfs_dir2_block.c:700 > xfs_dir2_block_lookup+0x19a/0x630 fs/xfs/libxfs/xfs_dir2_block.c:650 > xfs_dir_lookup+0x633/0xaf0 fs/xfs/libxfs/xfs_dir2.c:399 Hm. We've taken an ILOCK in xfs_dir_lookup, and now we're reading a directory block. We don't have PF_MEMALLOC_NOFS set, nor do we pass GFP_NOFS when allocating the xfs_buf pages. Nothing in this code path sets PF_MEMALLOC_NOFS explicitly, nor does it create a xfs_trans_alloc_empty, which would set that. Prior to the removal of kmem_alloc, I think we were much more aggressive about GFP_NOFS usage. Seeing as a lookup could involve walking a dabtree, we probably want the empty transaction to guard against dabtree cycle livelocks. This would be a good time to change xfs_bmapi_read to take a transaction parameter. --D > xfs_lookup+0x298/0x550 fs/xfs/xfs_inode.c:640 > xfs_vn_lookup+0x192/0x290 fs/xfs/xfs_iops.c:303 > lookup_open fs/namei.c:3475 [inline] > open_last_lookups fs/namei.c:3566 [inline] > path_openat+0x1035/0x3240 fs/namei.c:3796 > do_filp_open+0x235/0x490 fs/namei.c:3826 > do_sys_openat2+0x13e/0x1d0 fs/open.c:1406 > do_sys_open fs/open.c:1421 [inline] > __do_sys_openat fs/open.c:1437 [inline] > __se_sys_openat fs/open.c:1432 [inline] > __x64_sys_openat+0x247/0x2a0 fs/open.c:1432 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > > other info that might help us debug this: > > Possible unsafe locking scenario: > > CPU0 CPU1 > ---- ---- > rlock(&xfs_dir_ilock_class); > lock(fs_reclaim); > lock(&xfs_dir_ilock_class); > lock(fs_reclaim); > > *** DEADLOCK *** > > 3 locks held by syz-executor.2/7915: > #0: ffff8881d0472420 (sb_writers#14){.+.+}-{0:0}, at: mnt_want_write+0x3f/0x90 fs/namespace.c:409 > #1: ffff888056da8338 (&inode->i_sb->s_type->i_mutex_dir_key){++++}-{3:3}, at: inode_lock include/linux/fs.h:795 [inline] > #1: ffff888056da8338 (&inode->i_sb->s_type->i_mutex_dir_key){++++}-{3:3}, at: open_last_lookups fs/namei.c:3563 [inline] > #1: ffff888056da8338 (&inode->i_sb->s_type->i_mutex_dir_key){++++}-{3:3}, at: path_openat+0x7d3/0x3240 fs/namei.c:3796 > #2: ffff888056da8118 (&xfs_dir_ilock_class){++++}-{3:3}, at: xfs_ilock_data_map_shared+0x4f/0x70 fs/xfs/xfs_inode.c:114 > > stack backtrace: > CPU: 1 PID: 7915 Comm: syz-executor.2 Not tainted 6.9.0-rc4-syzkaller-00266-g977b1ef51866 #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024 > Call Trace: > <TASK> > __dump_stack lib/dump_stack.c:88 [inline] > dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114 > check_noncircular+0x36a/0x4a0 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+0x18cb/0x58e0 kernel/locking/lockdep.c:3869 > __lock_acquire+0x1346/0x1fd0 kernel/locking/lockdep.c:5137 > lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5754 > __fs_reclaim_acquire mm/page_alloc.c:3698 [inline] > fs_reclaim_acquire+0x88/0x140 mm/page_alloc.c:3712 > might_alloc include/linux/sched/mm.h:312 [inline] > slab_pre_alloc_hook mm/slub.c:3746 [inline] > slab_alloc_node mm/slub.c:3827 [inline] > kmalloc_trace+0x47/0x360 mm/slub.c:3992 > kmalloc include/linux/slab.h:628 [inline] > add_stack_record_to_list mm/page_owner.c:177 [inline] > inc_stack_record_count mm/page_owner.c:219 [inline] > __set_page_owner+0x561/0x810 mm/page_owner.c:334 > set_page_owner include/linux/page_owner.h:32 [inline] > post_alloc_hook+0x1ea/0x210 mm/page_alloc.c:1534 > prep_new_page mm/page_alloc.c:1541 [inline] > get_page_from_freelist+0x3410/0x35b0 mm/page_alloc.c:3317 > __alloc_pages+0x256/0x6c0 mm/page_alloc.c:4575 > __alloc_pages_bulk+0x729/0xd40 mm/page_alloc.c:4523 > alloc_pages_bulk_array include/linux/gfp.h:202 [inline] > xfs_buf_alloc_pages+0x1a7/0x860 fs/xfs/xfs_buf.c:398 > xfs_buf_find_insert+0x19a/0x1540 fs/xfs/xfs_buf.c:650 > xfs_buf_get_map+0x149c/0x1ae0 fs/xfs/xfs_buf.c:755 > xfs_buf_read_map+0x111/0xa60 fs/xfs/xfs_buf.c:860 > xfs_trans_read_buf_map+0x260/0xad0 fs/xfs/xfs_trans_buf.c:289 > xfs_da_read_buf+0x2b1/0x470 fs/xfs/libxfs/xfs_da_btree.c:2674 > xfs_dir3_block_read+0x92/0x1a0 fs/xfs/libxfs/xfs_dir2_block.c:145 > xfs_dir2_block_lookup_int+0x109/0x7d0 fs/xfs/libxfs/xfs_dir2_block.c:700 > xfs_dir2_block_lookup+0x19a/0x630 fs/xfs/libxfs/xfs_dir2_block.c:650 > xfs_dir_lookup+0x633/0xaf0 fs/xfs/libxfs/xfs_dir2.c:399 > xfs_lookup+0x298/0x550 fs/xfs/xfs_inode.c:640 > xfs_vn_lookup+0x192/0x290 fs/xfs/xfs_iops.c:303 > lookup_open fs/namei.c:3475 [inline] > open_last_lookups fs/namei.c:3566 [inline] > path_openat+0x1035/0x3240 fs/namei.c:3796 > do_filp_open+0x235/0x490 fs/namei.c:3826 > do_sys_openat2+0x13e/0x1d0 fs/open.c:1406 > do_sys_open fs/open.c:1421 [inline] > __do_sys_openat fs/open.c:1437 [inline] > __se_sys_openat fs/open.c:1432 [inline] > __x64_sys_openat+0x247/0x2a0 fs/open.c:1432 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7f23c887dea9 > Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 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 b0 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007f23c95950c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 > RAX: ffffffffffffffda RBX: 00007f23c89abf80 RCX: 00007f23c887dea9 > RDX: 000000000000275a RSI: 0000000020000080 RDI: ffffffffffffff9c > RBP: 00007f23c88ca4a4 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > R13: 000000000000000b R14: 00007f23c89abf80 R15: 00007fff62a26428 > </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 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 >
