[syzbot] [hfs?] INFO: task hung in hfs_find_init (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 052d534373b7 Merge tag 'exfat-for-6.8-rc1' of git://git.ke..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=13cf2debe80000
kernel config: https://syzkaller.appspot.com/x/.config?x=7c8840a4a09eab8
dashboard link: https://syzkaller.appspot.com/bug?extid=37463f2a5b94a8fdabec
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=151791f5e80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1569e90be80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/b1b0ffd73481/disk-052d5343.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c25614b900ba/vmlinux-052d5343.xz
kernel image: https://storage.googleapis.com/syzbot-assets/7dd1842e2ad4/bzImage-052d5343.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/6d0508568ec7/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+37463f...@syzkaller.appspotmail.com

INFO: task kworker/u4:1:12 blocked for more than 143 seconds.
Not tainted 6.7.0-syzkaller-09928-g052d534373b7 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:kworker/u4:1 state:D stack:23968 pid:12 tgid:12 ppid:2 flags:0x00004000
Workqueue: writeback wb_workfn (flush-7:0)
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5400 [inline]
__schedule+0xf12/0x5c00 kernel/sched/core.c:6727
__schedule_loop kernel/sched/core.c:6802 [inline]
schedule+0xe9/0x270 kernel/sched/core.c:6817
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6874
__mutex_lock_common kernel/locking/mutex.c:684 [inline]
__mutex_lock+0x5b9/0x9d0 kernel/locking/mutex.c:752
hfs_find_init+0x17f/0x220 fs/hfs/bfind.c:33
hfs_ext_write_extent+0x18e/0x1f0 fs/hfs/extent.c:141
hfs_write_inode+0xc4/0x9f0 fs/hfs/inode.c:427
write_inode fs/fs-writeback.c:1473 [inline]
__writeback_single_inode+0xa91/0xe90 fs/fs-writeback.c:1690
writeback_sb_inodes+0x599/0x1080 fs/fs-writeback.c:1916
__writeback_inodes_wb+0xff/0x2d0 fs/fs-writeback.c:1987
wb_writeback+0x7f8/0xaa0 fs/fs-writeback.c:2094
wb_check_background_flush fs/fs-writeback.c:2164 [inline]
wb_do_writeback fs/fs-writeback.c:2252 [inline]
wb_workfn+0x87c/0xfe0 fs/fs-writeback.c:2279
process_one_work+0x886/0x15d0 kernel/workqueue.c:2633
process_scheduled_works kernel/workqueue.c:2706 [inline]
worker_thread+0x8b9/0x1290 kernel/workqueue.c:2787
kthread+0x2c6/0x3a0 kernel/kthread.c:388
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242
</TASK>
INFO: task syz-executor755:5051 blocked for more than 143 seconds.
Not tainted 6.7.0-syzkaller-09928-g052d534373b7 #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor755 state:D stack:26976 pid:5051 tgid:5051 ppid:5049 flags:0x00004006
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5400 [inline]
__schedule+0xf12/0x5c00 kernel/sched/core.c:6727
__schedule_loop kernel/sched/core.c:6802 [inline]
schedule+0xe9/0x270 kernel/sched/core.c:6817
schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:6874
__mutex_lock_common kernel/locking/mutex.c:684 [inline]
__mutex_lock+0x5b9/0x9d0 kernel/locking/mutex.c:752
hfs_find_init+0x17f/0x220 fs/hfs/bfind.c:33
hfs_ext_read_extent+0x19c/0x9d0 fs/hfs/extent.c:200
hfs_extend_file+0x4e0/0xb10 fs/hfs/extent.c:401
hfs_bmap_reserve+0x29c/0x370 fs/hfs/btree.c:234
__hfs_ext_write_extent+0x3cb/0x520 fs/hfs/extent.c:121
__hfs_ext_cache_extent fs/hfs/extent.c:174 [inline]
hfs_ext_read_extent+0x805/0x9d0 fs/hfs/extent.c:202
hfs_extend_file+0x4e0/0xb10 fs/hfs/extent.c:401
hfs_get_block+0x17f/0x820 fs/hfs/extent.c:353
__block_write_begin_int+0x4fb/0x16e0 fs/buffer.c:2103
__block_write_begin fs/buffer.c:2152 [inline]
block_write_begin+0xb1/0x490 fs/buffer.c:2211
cont_write_begin+0x530/0x730 fs/buffer.c:2565
hfs_write_begin+0x87/0x140 fs/hfs/inode.c:53
generic_perform_write+0x278/0x600 mm/filemap.c:3928
__generic_file_write_iter+0x1f9/0x240 mm/filemap.c:4023
generic_file_write_iter+0xe3/0x350 mm/filemap.c:4049
call_write_iter include/linux/fs.h:2085 [inline]
new_sync_write fs/read_write.c:497 [inline]
vfs_write+0x64f/0xdf0 fs/read_write.c:590
ksys_write+0x12f/0x250 fs/read_write.c:643
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xd3/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f9a72ed2a59
RSP: 002b:00007ffcc7d3ea78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f9a72ed2a59
RDX: 000000000208e24b RSI: 0000000020000180 RDI: 0000000000000004
RBP: 00007f9a72f465f0 R08: 0000555555d2b4c0 R09: 0000555555d2b4c0
R10: 00000000000002ba R11: 0000000000000246 R12: 00007ffcc7d3eaa0
R13: 00007ffcc7d3ecc8 R14: 431bde82d7b634db R15: 00007f9a72f1b03b
</TASK>
INFO: lockdep is turned off.
NMI backtrace for cpu 1
CPU: 1 PID: 29 Comm: khungtaskd Not tainted 6.7.0-syzkaller-09928-g052d534373b7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
nmi_cpu_backtrace+0x277/0x390 lib/nmi_backtrace.c:113
nmi_trigger_cpumask_backtrace+0x299/0x300 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:160 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:222 [inline]
watchdog+0xf87/0x1210 kernel/hung_task.c:379
kthread+0x2c6/0x3a0 kernel/kthread.c:388
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242
</TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 PID: 11 Comm: kworker/u4:0 Not tainted 6.7.0-syzkaller-09928-g052d534373b7 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
Workqueue: events_unbound toggle_allocation_gate
RIP: 0010:__sanitizer_cov_trace_pc+0x0/0x60 kernel/kcov.c:200
Code: c6 71 e0 02 66 0f 1f 44 00 00 f3 0f 1e fa 48 8b be b0 01 00 00 e8 b0 ff ff ff 31 c0 c3 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 <f3> 0f 1e fa 65 48 8b 14 25 40 c2 03 00 65 8b 05 e4 c8 7c 7e a9 00
RSP: 0018:ffffc900001079a0 EFLAGS: 00000006
RAX: 0000000000000000 RBX: 0000000000000200 RCX: ffffffff812fe3af
RDX: ffff888015693b80 RSI: 0000000000000000 RDI: 0000000000000007
RBP: ffffffff81d45d23 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000000200 R11: 0000000000000000 R12: 0000000000000d27
R13: 0000000000000003 R14: ffffffff8d320100 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007feace266b90 CR3: 000000000cf79000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<NMI>
</NMI>
<TASK>
__text_poke+0x8d2/0xca0 arch/x86/kernel/alternative.c:1961
text_poke_bp_batch+0x3e0/0x750 arch/x86/kernel/alternative.c:2319
text_poke_flush arch/x86/kernel/alternative.c:2488 [inline]
text_poke_flush arch/x86/kernel/alternative.c:2485 [inline]
text_poke_finish+0x30/0x40 arch/x86/kernel/alternative.c:2495
arch_jump_label_transform_apply+0x1c/0x30 arch/x86/kernel/jump_label.c:146
jump_label_update+0x1d7/0x400 kernel/jump_label.c:829
static_key_disable_cpuslocked+0x154/0x1c0 kernel/jump_label.c:235
static_key_disable+0x1a/0x20 kernel/jump_label.c:243
toggle_allocation_gate mm/kfence/core.c:831 [inline]
toggle_allocation_gate+0x13f/0x250 mm/kfence/core.c:818
process_one_work+0x886/0x15d0 kernel/workqueue.c:2633
process_scheduled_works kernel/workqueue.c:2706 [inline]
worker_thread+0x8b9/0x1290 kernel/workqueue.c:2787
kthread+0x2c6/0x3a0 kernel/kthread.c:388
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:242
</TASK>
INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to run: 1.570 msecs


---
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[Edward Adam Davis]

please test possible deadlock in hfs_extend_file

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 610a9b8f49fb

diff --git a/fs/hfs/extent.c b/fs/hfs/extent.c
index 6d1878b99b30..1b02c7b6a10c 100644
--- a/fs/hfs/extent.c
+++ b/fs/hfs/extent.c
@@ -197,6 +197,10 @@ static int hfs_ext_read_extent(struct inode *inode, u16 block)
block < HFS_I(inode)->cached_start + HFS_I(inode)->cached_blocks)
return 0;

+ if (HFS_I(inode)->flags & HFS_FLG_EXT_DIRTY &&
+ HFS_I(inode)->flags & HFS_FLG_EXT_NEW)
+ return -ENOENT;
+
res = hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd);
if (!res) {
res = __hfs_ext_cache_extent(&fd, inode, block);

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

failed to checkout kernel repo https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git on commit 610a9b8f49fb: failed to run ["git" "fetch" "--force" "--tags" "4d52a57a3858a6eee0d0b25cc3a0c9533f747d8f" "610a9b8f49fb"]: exit status 128
fatal: couldn't find remote ref 610a9b8f49fb



Tested on:

commit: [unknown
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 610a9b8f49fb

kernel config: https://syzkaller.appspot.com/x/.config?x=7c8840a4a09eab8
dashboard link: https://syzkaller.appspot.com/bug?extid=37463f2a5b94a8fdabec
compiler:

patch: https://syzkaller.appspot.com/x/patch.diff?x=13675a3de80000