[syzbot] [kernfs?] possible deadlock in kernfs_fop_write_iter (2)

From: syzbot
Date: Mon Oct 14 2024 - 02:57:36 EST

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Hello,

syzbot found the following issue on:

HEAD commit: b983b271662b misc: sgi-gru: Don't disable preemption in GR..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17d53780580000
kernel config: https://syzkaller.appspot.com/x/.config?x=fb6ea01107fa96bd
dashboard link: https://syzkaller.appspot.com/bug?extid=1cfd86253864f61b533e
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7feb34a89c2a/non_bootable_disk-b983b271.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/a81cb8020fb3/vmlinux-b983b271.xz
kernel image: https://storage.googleapis.com/syzbot-assets/912e503e8fb2/bzImage-b983b271.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+1cfd86253864f61b533e@xxxxxxxxxxxxxxxxxxxxxxxxx

======================================================
WARNING: possible circular locking dependency detected
6.12.0-rc2-syzkaller-00061-gb983b271662b #0 Not tainted
------------------------------------------------------
syz.1.1735/11566 is trying to acquire lock:
ffff8880336f9088 (&of->mutex){+.+.}-{3:3}, at: kernfs_fop_write_iter+0x27b/0x500 fs/kernfs/file.c:325

but task is already holding lock:
ffff888027fa3868 (&pipe->mutex){+.+.}-{3:3}, at: pipe_lock fs/pipe.c:92 [inline]
ffff888027fa3868 (&pipe->mutex){+.+.}-{3:3}, at: pipe_lock+0x64/0x80 fs/pipe.c:89

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #3 (&pipe->mutex){+.+.}-{3:3}:
__mutex_lock_common kernel/locking/mutex.c:608 [inline]
__mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
pipe_lock fs/pipe.c:92 [inline]
pipe_lock+0x64/0x80 fs/pipe.c:89
iter_file_splice_write+0x1eb/0x10b0 fs/splice.c:687
do_splice_from fs/splice.c:941 [inline]
do_splice+0x145c/0x1f60 fs/splice.c:1354
__do_splice+0x327/0x360 fs/splice.c:1436
__do_sys_splice fs/splice.c:1652 [inline]
__se_sys_splice fs/splice.c:1634 [inline]
__x64_sys_splice+0x1cd/0x270 fs/splice.c:1634
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #2 (sb_writers#6){.+.+}-{0:0}:
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1716 [inline]
sb_start_write include/linux/fs.h:1852 [inline]
mnt_want_write+0x6f/0x450 fs/namespace.c:515
ovl_create_object+0x12e/0x300 fs/overlayfs/dir.c:642
lookup_open.isra.0+0x1174/0x14c0 fs/namei.c:3595
open_last_lookups fs/namei.c:3694 [inline]
path_openat+0x904/0x2d60 fs/namei.c:3930
do_filp_open+0x1dc/0x430 fs/namei.c:3960
do_sys_openat2+0x17a/0x1e0 fs/open.c:1415
do_sys_open fs/open.c:1430 [inline]
__do_sys_creat fs/open.c:1506 [inline]
__se_sys_creat fs/open.c:1500 [inline]
__x64_sys_creat+0xcd/0x120 fs/open.c:1500
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #1 (&ovl_i_mutex_dir_key[depth]){++++}-{3:3}:
down_read+0x9a/0x330 kernel/locking/rwsem.c:1524
inode_lock_shared include/linux/fs.h:825 [inline]
lookup_slow fs/namei.c:1748 [inline]
walk_component+0x342/0x5b0 fs/namei.c:2053
lookup_last fs/namei.c:2556 [inline]
path_lookupat+0x17f/0x770 fs/namei.c:2580
filename_lookup+0x1e5/0x5b0 fs/namei.c:2609
kern_path+0x35/0x50 fs/namei.c:2717
lookup_bdev+0xd9/0x280 block/bdev.c:1164
resume_store+0x1d8/0x460 kernel/power/hibernate.c:1239
kobj_attr_store+0x55/0x80 lib/kobject.c:840
sysfs_kf_write+0x117/0x170 fs/sysfs/file.c:136
kernfs_fop_write_iter+0x33d/0x500 fs/kernfs/file.c:334
new_sync_write fs/read_write.c:590 [inline]
vfs_write+0x6b5/0x1140 fs/read_write.c:683
ksys_write+0x12f/0x260 fs/read_write.c:736
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

-> #0 (&of->mutex){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3161 [inline]
check_prevs_add kernel/locking/lockdep.c:3280 [inline]
validate_chain kernel/locking/lockdep.c:3904 [inline]
__lock_acquire+0x250b/0x3ce0 kernel/locking/lockdep.c:5202
lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5825
__mutex_lock_common kernel/locking/mutex.c:608 [inline]
__mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
kernfs_fop_write_iter+0x27b/0x500 fs/kernfs/file.c:325
iter_file_splice_write+0x90f/0x10b0 fs/splice.c:743
do_splice_from fs/splice.c:941 [inline]
do_splice+0x145c/0x1f60 fs/splice.c:1354
__do_splice+0x327/0x360 fs/splice.c:1436
__do_sys_splice fs/splice.c:1652 [inline]
__se_sys_splice fs/splice.c:1634 [inline]
__x64_sys_splice+0x1cd/0x270 fs/splice.c:1634
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

other info that might help us debug this:

Chain exists of:
&of->mutex --> sb_writers#6 --> &pipe->mutex

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&pipe->mutex);
lock(sb_writers#6);
lock(&pipe->mutex);
lock(&of->mutex);

*** DEADLOCK ***

2 locks held by syz.1.1735/11566:
#0: ffff888029218420 (sb_writers#9){.+.+}-{0:0}, at: __do_splice+0x327/0x360 fs/splice.c:1436
#1: ffff888027fa3868 (&pipe->mutex){+.+.}-{3:3}, at: pipe_lock fs/pipe.c:92 [inline]
#1: ffff888027fa3868 (&pipe->mutex){+.+.}-{3:3}, at: pipe_lock+0x64/0x80 fs/pipe.c:89

stack backtrace:
CPU: 3 UID: 0 PID: 11566 Comm: syz.1.1735 Not tainted 6.12.0-rc2-syzkaller-00061-gb983b271662b #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
print_circular_bug+0x41c/0x610 kernel/locking/lockdep.c:2074
check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2206
check_prev_add kernel/locking/lockdep.c:3161 [inline]
check_prevs_add kernel/locking/lockdep.c:3280 [inline]
validate_chain kernel/locking/lockdep.c:3904 [inline]
__lock_acquire+0x250b/0x3ce0 kernel/locking/lockdep.c:5202
lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5825
__mutex_lock_common kernel/locking/mutex.c:608 [inline]
__mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752
kernfs_fop_write_iter+0x27b/0x500 fs/kernfs/file.c:325
iter_file_splice_write+0x90f/0x10b0 fs/splice.c:743
do_splice_from fs/splice.c:941 [inline]
do_splice+0x145c/0x1f60 fs/splice.c:1354
__do_splice+0x327/0x360 fs/splice.c:1436
__do_sys_splice fs/splice.c:1652 [inline]
__se_sys_splice fs/splice.c:1634 [inline]
__x64_sys_splice+0x1cd/0x270 fs/splice.c:1634
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f2d5977dff9
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:00007f2d5a4c5038 EFLAGS: 00000246 ORIG_RAX: 0000000000000113
RAX: ffffffffffffffda RBX: 00007f2d59936058 RCX: 00007f2d5977dff9
RDX: 000000000000000f RSI: 0000000000000000 RDI: 000000000000000d
RBP: 00007f2d597f0296 R08: 000000000000bfd1 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007f2d59936058 R15: 00007ffebf2e0bd8
</TASK>

---
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Next message: Sunil V L: "[PATCH] irqchip/riscv-intc: Fix no-SMP boot with ACPI"
Previous message: Krzysztof Kozlowski: "Re: [PATCH v3 13/16] dt-bindings: net: Add DT bindings for DWMAC on NXP S32G/R SoCs"
Messages sorted by: [ date ] [ thread ] [ subject ] [ author ]