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Date: Sat, 18 May 2024 11:53:32 -0700
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Subject: [syzbot] [nilfs?] possible deadlock in nilfs_evict_inode (2)
From: syzbot <syzbot+c48f1971ba117125f94c@syzkaller.appspotmail.com>
To: konishi.ryusuke@gmail.com, linux-kernel@vger.kernel.org, 
	linux-nilfs@vger.kernel.org, syzkaller-bugs@googlegroups.com
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Hello,

syzbot found the following issue on:

HEAD commit:    6bfd2d442af5 Merge tag 'irq-core-2024-05-12' of git://git...
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13aefc20980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=395546166dcfe360
dashboard link: https://syzkaller.appspot.com/bug?extid=c48f1971ba117125f94c
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-6bfd2d44.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/7ad901fe99c6/vmlinux-6bfd2d44.xz
kernel image: https://storage.googleapis.com/syzbot-assets/8d6ef2df621f/bzImage-6bfd2d44.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+c48f1971ba117125f94c@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.9.0-syzkaller-01893-g6bfd2d442af5 #0 Not tainted
------------------------------------------------------
kswapd0/111 is trying to acquire lock:
ffff888018e7e610 (sb_internal#4){.+.+}-{0:0}, at: nilfs_evict_inode+0x157/0x550 fs/nilfs2/inode.c:924

but task is already holding lock:
ffffffff8d9390c0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x166/0x1a10 mm/vmscan.c:6782

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (fs_reclaim){+.+.}-{0:0}:
       __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

-> #1 (&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_symlink+0x114/0x3c0 fs/nilfs2/namei.c:140
       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

-> #0 (sb_internal#4){.+.+}-{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
       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_evict_inode+0x157/0x550 fs/nilfs2/inode.c:924
       evict+0x2ed/0x6c0 fs/inode.c:667
       iput_final fs/inode.c:1741 [inline]
       iput.part.0+0x5a8/0x7f0 fs/inode.c:1767
       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

other info that might help us debug this:

Chain exists of:
  sb_internal#4 --> &nilfs->ns_segctor_sem --> fs_reclaim

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(fs_reclaim);
                               lock(&nilfs->ns_segctor_sem);
                               lock(fs_reclaim);
  rlock(sb_internal#4);

 *** DEADLOCK ***

2 locks held by kswapd0/111:
 #0: ffffffff8d9390c0 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat+0x166/0x1a10 mm/vmscan.c:6782
 #1: ffff888018e7e0e0 (&type->s_umount_key#74){++++}-{3:3}, at: super_trylock_shared fs/super.c:561 [inline]
 #1: ffff888018e7e0e0 (&type->s_umount_key#74){++++}-{3:3}, at: super_cache_scan+0x96/0x550 fs/super.c:196

stack backtrace:
CPU: 2 PID: 111 Comm: kswapd0 Not tainted 6.9.0-syzkaller-01893-g6bfd2d442af5 #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
 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_evict_inode+0x157/0x550 fs/nilfs2/inode.c:924
 evict+0x2ed/0x6c0 fs/inode.c:667
 iput_final fs/inode.c:1741 [inline]
 iput.part.0+0x5a8/0x7f0 fs/inode.c:1767
 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
 </TASK>


---
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