syzbot

======================================================
WARNING: possible circular locking dependency detected
6.13.0-rc6-next-20250107-syzkaller #0 Not tainted
------------------------------------------------------
syz.0.16/6005 is trying to acquire lock:
ffff88807f2835c8 (vm_lock){++++}-{0:0}, at: binder_alloc_free_page+0x150/0xd50 drivers/android/binder_alloc.c:1156

but task is already holding lock:
ffff88802eac0830 (&l->lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
ffff88802eac0830 (&l->lock){+.+.}-{3:3}, at: lock_list_lru_of_memcg+0x24c/0x4d0 mm/list_lru.c:77

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #4 (&l->lock){+.+.}-{3:3}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
       _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
       spin_lock include/linux/spinlock.h:351 [inline]
       lock_list_lru_of_memcg+0x24c/0x4d0 mm/list_lru.c:77
       list_lru_add+0x59/0x270 mm/list_lru.c:163
       list_lru_add_obj+0x17b/0x250 mm/list_lru.c:186
       __inode_add_lru fs/inode.c:534 [inline]
       iput_final fs/inode.c:1923 [inline]
       iput+0x89c/0xa50 fs/inode.c:1972
       __dentry_kill+0x20d/0x630 fs/dcache.c:625
       shrink_kill+0xa9/0x2c0 fs/dcache.c:1070
       shrink_dentry_list+0x2c0/0x5b0 fs/dcache.c:1097
       shrink_dcache_sb+0x25e/0x3e0 fs/dcache.c:1217
       reconfigure_super+0x2c6/0x870 fs/super.c:1061
       do_remount fs/namespace.c:3100 [inline]
       path_mount+0xc22/0xfa0 fs/namespace.c:3879
       do_mount fs/namespace.c:3900 [inline]
       __do_sys_mount fs/namespace.c:4111 [inline]
       __se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4088
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #3 (&sb->s_type->i_lock_key#23){+.+.}-{3:3}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
       __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
       _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
       spin_lock include/linux/spinlock.h:351 [inline]
       d_instantiate_new+0x76/0x130 fs/dcache.c:1922
       ext4_add_nondir+0x21e/0x290 fs/ext4/namei.c:2808
       ext4_create+0x377/0x550 fs/ext4/namei.c:2849
       lookup_open fs/namei.c:3649 [inline]
       open_last_lookups fs/namei.c:3748 [inline]
       path_openat+0x192f/0x3580 fs/namei.c:3984
       do_filp_open+0x27f/0x4e0 fs/namei.c:4014
       do_sys_openat2+0x13e/0x1d0 fs/open.c:1427
       do_sys_open fs/open.c:1442 [inline]
       __do_sys_openat fs/open.c:1458 [inline]
       __se_sys_openat fs/open.c:1453 [inline]
       __x64_sys_openat+0x247/0x2a0 fs/open.c:1453
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (jbd2_handle){++++}-{0:0}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
       start_this_handle+0x1eb4/0x2110 fs/jbd2/transaction.c:448
       jbd2__journal_start+0x2da/0x5d0 fs/jbd2/transaction.c:505
       __ext4_journal_start_sb+0x239/0x600 fs/ext4/ext4_jbd2.c:112
       __ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline]
       ext4_dirty_inode+0x92/0x110 fs/ext4/inode.c:6039
       __mark_inode_dirty+0x2ee/0xe90 fs/fs-writeback.c:2515
       generic_update_time fs/inode.c:2112 [inline]
       inode_update_time fs/inode.c:2125 [inline]
       __file_update_time fs/inode.c:2353 [inline]
       file_update_time+0x3d2/0x450 fs/inode.c:2383
       ext4_page_mkwrite+0x210/0x1100 fs/ext4/inode.c:6160
       do_page_mkwrite+0x159/0x340 mm/memory.c:3244
       do_shared_fault mm/memory.c:5468 [inline]
       do_fault mm/memory.c:5530 [inline]
       do_pte_missing mm/memory.c:4047 [inline]
       handle_pte_fault mm/memory.c:5889 [inline]
       __handle_mm_fault+0x22dc/0x70f0 mm/memory.c:6032
       handle_mm_fault+0x3e2/0x8c0 mm/memory.c:6201
       do_user_addr_fault arch/x86/mm/fault.c:1388 [inline]
       handle_page_fault arch/x86/mm/fault.c:1480 [inline]
       exc_page_fault+0x2b9/0x8b0 arch/x86/mm/fault.c:1538
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

-> #1 (sb_pagefaults){.+.+}-{0:0}:
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
       percpu_down_read+0x44/0x1b0 include/linux/percpu-rwsem.h:51
       __sb_start_write include/linux/fs.h:1773 [inline]
       sb_start_pagefault include/linux/fs.h:1938 [inline]
       ext4_page_mkwrite+0x1f9/0x1100 fs/ext4/inode.c:6159
       do_page_mkwrite+0x159/0x340 mm/memory.c:3244
       do_shared_fault mm/memory.c:5468 [inline]
       do_fault mm/memory.c:5530 [inline]
       do_pte_missing mm/memory.c:4047 [inline]
       handle_pte_fault mm/memory.c:5889 [inline]
       __handle_mm_fault+0x22dc/0x70f0 mm/memory.c:6032
       handle_mm_fault+0x3e2/0x8c0 mm/memory.c:6201
       do_user_addr_fault arch/x86/mm/fault.c:1337 [inline]
       handle_page_fault arch/x86/mm/fault.c:1480 [inline]
       exc_page_fault+0x459/0x8b0 arch/x86/mm/fault.c:1538
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623

-> #0 (vm_lock){++++}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3163 [inline]
       check_prevs_add kernel/locking/lockdep.c:3282 [inline]
       validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906
       __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
       lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
       vma_start_read include/linux/mm.h:749 [inline]
       lock_vma_under_rcu+0x35f/0x9a0 mm/memory.c:6436
       binder_alloc_free_page+0x150/0xd50 drivers/android/binder_alloc.c:1156
       __list_lru_walk_one+0x170/0x470 mm/list_lru.c:300
       list_lru_walk_one mm/list_lru.c:337 [inline]
       list_lru_walk_node+0xc4/0xa70 mm/list_lru.c:357
       list_lru_walk include/linux/list_lru.h:282 [inline]
       binder_shrink_scan+0x138/0x260 drivers/android/binder_alloc.c:1226
       do_shrink_slab+0x72d/0x1160 mm/shrinker.c:437
       shrink_slab+0x1093/0x14d0 mm/shrinker.c:664
       drop_slab_node mm/vmscan.c:421 [inline]
       drop_slab+0x142/0x280 mm/vmscan.c:439
       drop_caches_sysctl_handler+0xbc/0x160 fs/drop_caches.c:68
       proc_sys_call_handler+0x5ec/0x920 fs/proc/proc_sysctl.c:601
       do_iter_readv_writev+0x71a/0x9d0
       vfs_writev+0x38b/0xbc0 fs/read_write.c:1050
       do_writev+0x1b6/0x360 fs/read_write.c:1096
       do_syscall_x64 arch/x86/entry/common.c:52 [inline]
       do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
       entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
  vm_lock --> &sb->s_type->i_lock_key#23 --> &l->lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&l->lock);
                               lock(&sb->s_type->i_lock_key#23);
                               lock(&l->lock);
  rlock(vm_lock);

 *** DEADLOCK ***

3 locks held by syz.0.16/6005:
 #0: ffff888033bec420 (sb_writers#3){.+.+}-{0:0}, at: file_start_write include/linux/fs.h:3016 [inline]
 #0: ffff888033bec420 (sb_writers#3){.+.+}-{0:0}, at: vfs_writev+0x2d6/0xbc0 fs/read_write.c:1048
 #1: ffff88802eac0830 (&l->lock){+.+.}-{3:3}, at: spin_lock include/linux/spinlock.h:351 [inline]
 #1: ffff88802eac0830 (&l->lock){+.+.}-{3:3}, at: lock_list_lru_of_memcg+0x24c/0x4d0 mm/list_lru.c:77
 #2: ffffffff8e937ee0 (rcu_read_lock){....}-{1:3}, at: rcu_lock_acquire include/linux/rcupdate.h:337 [inline]
 #2: ffffffff8e937ee0 (rcu_read_lock){....}-{1:3}, at: rcu_read_lock include/linux/rcupdate.h:849 [inline]
 #2: ffffffff8e937ee0 (rcu_read_lock){....}-{1:3}, at: lock_vma_under_rcu+0x1dd/0x9a0 mm/memory.c:6431

stack backtrace:
CPU: 0 UID: 0 PID: 6005 Comm: syz.0.16 Not tainted 6.13.0-rc6-next-20250107-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_circular_bug+0x13a/0x1b0 kernel/locking/lockdep.c:2076
 check_noncircular+0x36a/0x4a0 kernel/locking/lockdep.c:2208
 check_prev_add kernel/locking/lockdep.c:3163 [inline]
 check_prevs_add kernel/locking/lockdep.c:3282 [inline]
 validate_chain+0x18ef/0x5920 kernel/locking/lockdep.c:3906
 __lock_acquire+0x1397/0x2100 kernel/locking/lockdep.c:5228
 lock_acquire+0x1ed/0x550 kernel/locking/lockdep.c:5851
 vma_start_read include/linux/mm.h:749 [inline]
 lock_vma_under_rcu+0x35f/0x9a0 mm/memory.c:6436
 binder_alloc_free_page+0x150/0xd50 drivers/android/binder_alloc.c:1156
 __list_lru_walk_one+0x170/0x470 mm/list_lru.c:300
 list_lru_walk_one mm/list_lru.c:337 [inline]
 list_lru_walk_node+0xc4/0xa70 mm/list_lru.c:357
 list_lru_walk include/linux/list_lru.h:282 [inline]
 binder_shrink_scan+0x138/0x260 drivers/android/binder_alloc.c:1226
 do_shrink_slab+0x72d/0x1160 mm/shrinker.c:437
 shrink_slab+0x1093/0x14d0 mm/shrinker.c:664
 drop_slab_node mm/vmscan.c:421 [inline]
 drop_slab+0x142/0x280 mm/vmscan.c:439
 drop_caches_sysctl_handler+0xbc/0x160 fs/drop_caches.c:68
 proc_sys_call_handler+0x5ec/0x920 fs/proc/proc_sysctl.c:601
 do_iter_readv_writev+0x71a/0x9d0
 vfs_writev+0x38b/0xbc0 fs/read_write.c:1050
 do_writev+0x1b6/0x360 fs/read_write.c:1096
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc4e3d85d29
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:00007fffafb25958 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 00007fc4e3f75fa0 RCX: 00007fc4e3d85d29
RDX: 0000000000000001 RSI: 00000000200000c0 RDI: 0000000000000003
RBP: 00007fc4e3e01b08 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc4e3f75fa0 R14: 00007fc4e3f75fa0 R15: 00000000000019d2
 </TASK>
syz.0.16 (6005): drop_caches: 2