[syzbot] [xfs?] possible deadlock in xfs_can_free_eofblocks

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May 10, 2024, 2:05:35 PMMay 10
to chanda...@oracle.com, djw...@kernel.org, linux-...@vger.kernel.org, linu...@vger.kernel.org, syzkall...@googlegroups.com
Hello,

syzbot found the following issue on:

HEAD commit: dd5a440a31fa Linux 6.9-rc7
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=11059824980000
kernel config: https://syzkaller.appspot.com/x/.config?x=6d14c12b661fb43
dashboard link: https://syzkaller.appspot.com/bug?extid=1ac5b398842451b74cec
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/58e2a4900479/disk-dd5a440a.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/246a109c32d6/vmlinux-dd5a440a.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d2719f7eb672/bzImage-dd5a440a.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1ac5b3...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
6.9.0-rc7-syzkaller #0 Not tainted
------------------------------------------------------
kswapd0/89 is trying to acquire lock:
ffff8880540b9858
(&xfs_nondir_ilock_class#3){++++}-{3:3}, at: xfs_can_free_eofblocks+0x645/0x910 fs/xfs/xfs_bmap_util.c:555

but task is already holding lock:
ffffffff8e42a780 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6782 [inline]
ffffffff8e42a780 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xbe8/0x38a0 mm/vmscan.c:7164

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (fs_reclaim){+.+.}-{0:0}:
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_mpol+0x3e8/0x680 mm/mempolicy.c:2264
stack_depot_save_flags+0x666/0x830 lib/stackdepot.c:635
kasan_save_stack mm/kasan/common.c:48 [inline]
kasan_save_track+0x51/0x80 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
__kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387
kasan_kmalloc include/linux/kasan.h:211 [inline]
kmalloc_trace+0x1db/0x360 mm/slub.c:3997
kmalloc include/linux/slab.h:628 [inline]
kzalloc include/linux/slab.h:749 [inline]
xfs_iext_alloc_node fs/xfs/libxfs/xfs_iext_tree.c:401 [inline]
xfs_iext_alloc_root fs/xfs/libxfs/xfs_iext_tree.c:593 [inline]
xfs_iext_insert_raw+0x206/0x23d0 fs/xfs/libxfs/xfs_iext_tree.c:645
xfs_iext_insert+0x38/0x250 fs/xfs/libxfs/xfs_iext_tree.c:684
xfs_bmap_add_extent_hole_delay+0x573/0xc20 fs/xfs/libxfs/xfs_bmap.c:2686
xfs_bmapi_reserve_delalloc+0x897/0x9b0 fs/xfs/libxfs/xfs_bmap.c:4128
xfs_buffered_write_iomap_begin+0x1243/0x1b40 fs/xfs/xfs_iomap.c:1130
iomap_iter+0x693/0xf60 fs/iomap/iter.c:91
iomap_zero_range+0x16e/0x6e0 fs/iomap/buffered-io.c:1426
xfs_setattr_size+0x384/0xc80 fs/xfs/xfs_iops.c:858
xfs_vn_setattr+0x25d/0x320 fs/xfs/xfs_iops.c:1020
notify_change+0xb9f/0xe70 fs/attr.c:497
do_truncate fs/open.c:65 [inline]
do_ftruncate+0x46b/0x590 fs/open.c:181
do_sys_ftruncate fs/open.c:199 [inline]
__do_sys_ftruncate fs/open.c:207 [inline]
__se_sys_ftruncate fs/open.c:205 [inline]
__x64_sys_ftruncate+0x95/0xf0 fs/open.c:205
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

-> #0 (&xfs_nondir_ilock_class#3){++++}-{3:3}:
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
down_read_nested+0xb5/0xa50 kernel/locking/rwsem.c:1651
xfs_can_free_eofblocks+0x645/0x910 fs/xfs/xfs_bmap_util.c:555
xfs_inode_mark_reclaimable+0x1bb/0xf60 fs/xfs/xfs_icache.c:2149
destroy_inode fs/inode.c:311 [inline]
evict+0x54b/0x630 fs/inode.c:682
dispose_list fs/inode.c:700 [inline]
prune_icache_sb+0x239/0x2f0 fs/inode.c:885
super_cache_scan+0x38c/0x4b0 fs/super.c:223
do_shrink_slab+0x707/0x1160 mm/shrinker.c:435
shrink_slab_memcg mm/shrinker.c:548 [inline]
shrink_slab+0x883/0x14d0 mm/shrinker.c:626
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

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(fs_reclaim);
lock(&xfs_nondir_ilock_class#3);
lock(fs_reclaim);
rlock(&xfs_nondir_ilock_class#3);

*** DEADLOCK ***

2 locks held by kswapd0/89:
#0: ffffffff8e42a780 (fs_reclaim){+.+.}-{0:0}, at: balance_pgdat mm/vmscan.c:6782 [inline]
#0: ffffffff8e42a780 (fs_reclaim){+.+.}-{0:0}, at: kswapd+0xbe8/0x38a0 mm/vmscan.c:7164
#1: ffff8880796d20e0 (&type->s_umount_key#66){++++}-{3:3}, at: super_trylock_shared fs/super.c:561 [inline]
#1: ffff8880796d20e0 (&type->s_umount_key#66){++++}-{3:3}, at: super_cache_scan+0x94/0x4b0 fs/super.c:196

stack backtrace:
CPU: 0 PID: 89 Comm: kswapd0 Not tainted 6.9.0-rc7-syzkaller #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
down_read_nested+0xb5/0xa50 kernel/locking/rwsem.c:1651
xfs_can_free_eofblocks+0x645/0x910 fs/xfs/xfs_bmap_util.c:555
xfs_inode_mark_reclaimable+0x1bb/0xf60 fs/xfs/xfs_icache.c:2149
destroy_inode fs/inode.c:311 [inline]
evict+0x54b/0x630 fs/inode.c:682
dispose_list fs/inode.c:700 [inline]
prune_icache_sb+0x239/0x2f0 fs/inode.c:885
super_cache_scan+0x38c/0x4b0 fs/super.c:223
do_shrink_slab+0x707/0x1160 mm/shrinker.c:435
shrink_slab_memcg mm/shrinker.c:548 [inline]
shrink_slab+0x883/0x14d0 mm/shrinker.c:626
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
</TASK>


---
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