[syzbot] [ext4?] possible deadlock in ext4_evict_inode (3)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 445a555e0623 Add linux-next specific files for 20240209
git tree: linux-next
console output: https://syzkaller.appspot.com/x/log.txt?x=11187fd4180000
kernel config: https://syzkaller.appspot.com/x/.config?x=85aa3388229f9ea9
dashboard link: https://syzkaller.appspot.com/bug?extid=295234f4b13c00852ba4
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/9188bb84c998/disk-445a555e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/3ce0c98eabb2/vmlinux-445a555e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ab801b1c1d6d/bzImage-445a555e.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+295234...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.8.0-rc3-next-20240209-syzkaller #0 Not tainted
------------------------------------------------------
kswapd0/87 is trying to acquire lock:
ffff88802ed52610 (sb_internal){.+.+}-{0:0}, at: __sb_start_write include/linux/fs.h:1657 [inline]
ffff88802ed52610 (sb_internal){.+.+}-{0:0}, at: sb_start_intwrite include/linux/fs.h:1840 [inline]
ffff88802ed52610 (sb_internal){.+.+}-{0:0}, at: ext4_evict_inode+0x2e4/0xf30 fs/ext4/inode.c:212

but task is already holding lock:
ffffffff8e21a620 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6790 [inline]
ffffffff8e21a620 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xb8a/0x3570 mm/vmscan.c:7162

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (fs_reclaim){+.+.}-{0:0}:
lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
__fs_reclaim_acquire mm/page_alloc.c:3734 [inline]
fs_reclaim_acquire+0x88/0x140 mm/page_alloc.c:3748
might_alloc include/linux/sched/mm.h:312 [inline]
slab_pre_alloc_hook mm/slub.c:3762 [inline]
slab_alloc_node mm/slub.c:3843 [inline]
kmem_cache_alloc+0x48/0x350 mm/slub.c:3868
ext4_es_insert_delayed_block+0x2d9/0xa10 fs/ext4/extents_status.c:2090
ext4_insert_delayed_block fs/ext4/inode.c:1676 [inline]
ext4_da_map_blocks fs/ext4/inode.c:1777 [inline]
ext4_da_get_block_prep+0xa67/0x1420 fs/ext4/inode.c:1817
ext4_block_write_begin+0x53b/0x1850 fs/ext4/inode.c:1055
ext4_da_write_begin+0x5e8/0xa50 fs/ext4/inode.c:2894
generic_perform_write+0x322/0x640 mm/filemap.c:3921
ext4_buffered_write_iter+0xc6/0x350 fs/ext4/file.c:299
ext4_file_write_iter+0x1de/0x1a10
call_write_iter include/linux/fs.h:2103 [inline]
iter_file_splice_write+0xbd7/0x14e0 fs/splice.c:743
do_splice_from fs/splice.c:941 [inline]
direct_splice_actor+0x11e/0x220 fs/splice.c:1164
splice_direct_to_actor+0x58e/0xc90 fs/splice.c:1108
do_splice_direct_actor fs/splice.c:1207 [inline]
do_splice_direct+0x28c/0x3e0 fs/splice.c:1233
do_sendfile+0x56d/0xdc0 fs/read_write.c:1295
__do_sys_sendfile64 fs/read_write.c:1362 [inline]
__se_sys_sendfile64+0x17c/0x1e0 fs/read_write.c:1348
do_syscall_64+0xfb/0x240
entry_SYSCALL_64_after_hwframe+0x6d/0x75

-> #2 (&ei->i_data_sem){++++}-{3:3}:
lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
down_write+0x3a/0x50 kernel/locking/rwsem.c:1579
ext4_map_blocks+0x988/0x1d20 fs/ext4/inode.c:616
mpage_map_one_extent fs/ext4/inode.c:2163 [inline]
mpage_map_and_submit_extent fs/ext4/inode.c:2216 [inline]
ext4_do_writepages+0x15e1/0x3ca0 fs/ext4/inode.c:2679
ext4_writepages+0x213/0x3c0 fs/ext4/inode.c:2768
do_writepages+0x3a4/0x670 mm/page-writeback.c:2553
__writeback_single_inode+0x155/0xfd0 fs/fs-writeback.c:1650
writeback_sb_inodes+0x8e4/0x1220 fs/fs-writeback.c:1941
__writeback_inodes_wb+0x11b/0x260 fs/fs-writeback.c:2012
wb_writeback+0x45b/0xc70 fs/fs-writeback.c:2119
wb_check_background_flush fs/fs-writeback.c:2189 [inline]
wb_do_writeback fs/fs-writeback.c:2277 [inline]
wb_workfn+0xc33/0x1070 fs/fs-writeback.c:2304
process_one_work kernel/workqueue.c:3143 [inline]
process_scheduled_works+0x9d7/0x1730 kernel/workqueue.c:3223
worker_thread+0x86d/0xd70 kernel/workqueue.c:3304
kthread+0x2f0/0x390 kernel/kthread.c:388
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:242

-> #1 (jbd2_handle){++++}-{0:0}:
lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
start_this_handle+0x1fc7/0x2200 fs/jbd2/transaction.c:463
jbd2__journal_start+0x306/0x620 fs/jbd2/transaction.c:520
__ext4_journal_start_sb+0x215/0x5b0 fs/ext4/ext4_jbd2.c:112
ext4_sample_last_mounted fs/ext4/file.c:837 [inline]
ext4_file_open+0x53e/0x760 fs/ext4/file.c:866
do_dentry_open+0x907/0x15a0 fs/open.c:953
do_open fs/namei.c:3639 [inline]
path_openat+0x2860/0x3240 fs/namei.c:3796
do_filp_open+0x235/0x490 fs/namei.c:3823
do_sys_openat2+0x13e/0x1d0 fs/open.c:1404
do_sys_open fs/open.c:1419 [inline]
__do_sys_openat fs/open.c:1435 [inline]
__se_sys_openat fs/open.c:1430 [inline]
__x64_sys_openat+0x247/0x2a0 fs/open.c:1430
do_syscall_64+0xfb/0x240
entry_SYSCALL_64_after_hwframe+0x6d/0x75

-> #0 (sb_internal){.+.+}-{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+0x1e4/0x530 kernel/locking/lockdep.c:5754
percpu_down_read+0x44/0x1b0 include/linux/percpu-rwsem.h:51
__sb_start_write include/linux/fs.h:1657 [inline]
sb_start_intwrite include/linux/fs.h:1840 [inline]
ext4_evict_inode+0x2e4/0xf30 fs/ext4/inode.c:212
evict+0x2a8/0x630 fs/inode.c:666
__dentry_kill+0x20d/0x630 fs/dcache.c:603
shrink_kill+0xa9/0x2c0 fs/dcache.c:1048
shrink_dentry_list+0x2c0/0x5b0 fs/dcache.c:1075
prune_dcache_sb+0x10f/0x180 fs/dcache.c:1156
super_cache_scan+0x34f/0x4b0 fs/super.c:221
do_shrink_slab+0x6d0/0x1140 mm/shrinker.c:435
shrink_slab_memcg mm/shrinker.c:548 [inline]
shrink_slab+0x883/0x14d0 mm/shrinker.c:626
shrink_one+0x423/0x7f0 mm/vmscan.c:4784
shrink_many mm/vmscan.c:4845 [inline]
lru_gen_shrink_node mm/vmscan.c:4946 [inline]
shrink_node+0x358a/0x3b60 mm/vmscan.c:5905
kswapd_shrink_node mm/vmscan.c:6712 [inline]
balance_pgdat mm/vmscan.c:6903 [inline]
kswapd+0x1815/0x3570 mm/vmscan.c:7162
kthread+0x2f0/0x390 kernel/kthread.c:388
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:242

other info that might help us debug this:

Chain exists of:
sb_internal --> &ei->i_data_sem --> fs_reclaim

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(fs_reclaim);
lock(&ei->i_data_sem);
lock(fs_reclaim);
rlock(sb_internal);

*** DEADLOCK ***

2 locks held by kswapd0/87:
#0: ffffffff8e21a620 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6790 [inline]
#0: ffffffff8e21a620 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xb8a/0x3570 mm/vmscan.c:7162
#1: ffff88802ed520e0 (&type->s_umount_key#31){++++}-{3:3}, at: super_trylock_shared fs/super.c:566 [inline]
#1: ffff88802ed520e0 (&type->s_umount_key#31){++++}-{3:3}, at: super_cache_scan+0x94/0x4b0 fs/super.c:196

stack backtrace:
CPU: 1 PID: 87 Comm: kswapd0 Not tainted 6.8.0-rc3-next-20240209-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
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+0x1e4/0x530 kernel/locking/lockdep.c:5754
percpu_down_read+0x44/0x1b0 include/linux/percpu-rwsem.h:51
__sb_start_write include/linux/fs.h:1657 [inline]
sb_start_intwrite include/linux/fs.h:1840 [inline]
ext4_evict_inode+0x2e4/0xf30 fs/ext4/inode.c:212
evict+0x2a8/0x630 fs/inode.c:666
__dentry_kill+0x20d/0x630 fs/dcache.c:603
shrink_kill+0xa9/0x2c0 fs/dcache.c:1048
shrink_dentry_list+0x2c0/0x5b0 fs/dcache.c:1075
prune_dcache_sb+0x10f/0x180 fs/dcache.c:1156
super_cache_scan+0x34f/0x4b0 fs/super.c:221
do_shrink_slab+0x6d0/0x1140 mm/shrinker.c:435
shrink_slab_memcg mm/shrinker.c:548 [inline]
shrink_slab+0x883/0x14d0 mm/shrinker.c:626
shrink_one+0x423/0x7f0 mm/vmscan.c:4784
shrink_many mm/vmscan.c:4845 [inline]
lru_gen_shrink_node mm/vmscan.c:4946 [inline]
shrink_node+0x358a/0x3b60 mm/vmscan.c:5905
kswapd_shrink_node mm/vmscan.c:6712 [inline]
balance_pgdat mm/vmscan.c:6903 [inline]
kswapd+0x1815/0x3570 mm/vmscan.c:7162
kthread+0x2f0/0x390 kernel/kthread.c:388
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:242
</TASK>


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