Subject: [syzbot] [mm?] possible deadlock in __mmap_lock_do_trace_start_locking

From: syzbot <[email-masked]>
Date: Thu, 25 Apr 2024 19:33:22 -0700

Hello,

syzbot found the following issue on:

HEAD commit:    443574b03387 riscv, bpf: Fix kfunc parameters incompatibil..
git tree:       bpf
console output: https://syzkaller.appspot.com/x/log.txt?x=13601320980000
kernel config:  https://syzkaller.appspot.com/x/.config?x=6fb1be60a193d440
dashboard link: https://syzkaller.appspot.com/bug?extid=6ff90931779bcdfc840c
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/3f355021a085/disk-443574b0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/44cf4de7472a/vmlinux-443574b0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/a99a36c7ad65/bzImage-443574b0.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

======================================================
WARNING: possible circular locking dependency detected
6.8.0-syzkaller-05236-g443574b03387 #0 Not tainted
------------------------------------------------------
syz-executor.2/5452 is trying to acquire lock:
ffff8880b9538528 (lock#10){+.+.}-{2:2}, at: local_lock_acquire include/linux/local_lock_internal.h:29 [inline]
ffff8880b9538528 (lock#10){+.+.}-{2:2}, at: __mmap_lock_do_trace_start_locking+0x83/0x5f0 mm/mmap_lock.c:230

but task is already holding lock:
ffff8880b953e158 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (&rq->__lock){-.-.}-{2:2}:
       lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
       _raw_spin_lock_nested+0x31/0x40 kernel/locking/spinlock.c:378
       raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559
       raw_spin_rq_lock kernel/sched/sched.h:1385 [inline]
       rq_lock kernel/sched/sched.h:1699 [inline]
       task_fork_fair+0x61/0x1e0 kernel/sched/fair.c:12629
       sched_cgroup_fork+0x37c/0x410 kernel/sched/core.c:4845
       copy_process+0x2217/0x3df0 kernel/fork.c:2498
       kernel_clone+0x21e/0x8d0 kernel/fork.c:2796
       user_mode_thread+0x132/0x1a0 kernel/fork.c:2874
       rest_init+0x27/0x300 init/main.c:695
       arch_call_rest_init+0xe/0x10 init/main.c:831
       start_kernel+0x47a/0x500 init/main.c:1077
       x86_64_start_reservations+0x2a/0x30 arch/x86/kernel/head64.c:509
       x86_64_start_kernel+0x99/0xa0 arch/x86/kernel/head64.c:490
       common_startup_64+0x13e/0x147

-> #1 (&p->pi_lock){-.-.}-{2:2}:
       lock_acquire+0x1e4/0x530 kernel/locking/lockdep.c:5754
       __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
       _raw_spin_lock_irqsave+0xd5/0x120 kernel/locking/spinlock.c:162
       class_raw_spinlock_irqsave_constructor include/linux/spinlock.h:553 [inline]
       try_to_wake_up+0xb0/0x1470 kernel/sched/core.c:4262
       rcu_read_unlock_special+0x3db/0x550 kernel/rcu/tree_plugin.h:655
       __rcu_read_unlock+0xa1/0x110 kernel/rcu/tree_plugin.h:426
       rcu_read_unlock include/linux/rcupdate.h:782 [inline]
       get_mem_cgroup_from_mm+0x1a3/0x2a0 mm/memcontrol.c:1112
       get_mm_memcg_path+0x1b/0x600 mm/mmap_lock.c:202
       __mmap_lock_do_trace_start_locking+0x134/0x5f0 mm/mmap_lock.c:230
       __mmap_lock_trace_start_locking include/linux/mmap_lock.h:29 [inline]
       mmap_read_trylock include/linux/mmap_lock.h:164 [inline]
       get_mmap_lock_carefully mm/memory.c:5497 [inline]
       lock_mm_and_find_vma+0x1f1/0x2f0 mm/memory.c:5557
       do_user_addr_fault arch/x86/mm/fault.c:1385 [inline]
       handle_page_fault arch/x86/mm/fault.c:1505 [inline]
       exc_page_fault+0x1a9/0x890 arch/x86/mm/fault.c:1563
       asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623
       rep_movs_alternative+0x4a/0x70 arch/x86/lib/copy_user_64.S:65
       copy_user_generic arch/x86/include/asm/uaccess_64.h:110 [inline]
       raw_copy_from_user arch/x86/include/asm/uaccess_64.h:125 [inline]
       copy_from_user_iter lib/iov_iter.c:55 [inline]
       iterate_ubuf include/linux/iov_iter.h:29 [inline]
       iterate_and_advance2 include/linux/iov_iter.h:245 [inline]
       iterate_and_advance include/linux/iov_iter.h:271 [inline]
       __copy_from_iter lib/iov_iter.c:249 [inline]
       _copy_from_iter+0x257/0x1cf0 lib/iov_iter.c:260
       copy_from_iter include/linux/uio.h:204 [inline]
       copy_from_iter_full include/linux/uio.h:211 [inline]
       skb_do_copy_data_nocache include/net/sock.h:2231 [inline]
       skb_copy_to_page_nocache include/net/sock.h:2257 [inline]
       kcm_sendmsg+0xcca/0x27c0 net/kcm/kcmsock.c:858
       sock_sendmsg_nosec net/socket.c:730 [inline]
       __sock_sendmsg+0x221/0x270 net/socket.c:745
       sock_write_iter+0x2dd/0x400 net/socket.c:1160
       call_write_iter include/linux/fs.h:2108 [inline]
       new_sync_write fs/read_write.c:497 [inline]
       vfs_write+0xa84/0xcb0 fs/read_write.c:590
       ksys_write+0x1a0/0x2c0 fs/read_write.c:643
       do_syscall_64+0xfb/0x240
       entry_SYSCALL_64_after_hwframe+0x6d/0x75

-> #0 (lock#10){+.+.}-{2:2}:
       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
       local_lock_acquire include/linux/local_lock_internal.h:29 [inline]
       __mmap_lock_do_trace_start_locking+0x9c/0x5f0 mm/mmap_lock.c:230
       __mmap_lock_trace_start_locking include/linux/mmap_lock.h:29 [inline]
       mmap_read_trylock include/linux/mmap_lock.h:164 [inline]
       stack_map_get_build_id_offset+0x98d/0x9d0 kernel/bpf/stackmap.c:141
       __bpf_get_stack+0x4ad/0x5a0 kernel/bpf/stackmap.c:449
       ____bpf_get_stack_raw_tp kernel/trace/bpf_trace.c:1985 [inline]
       bpf_get_stack_raw_tp+0x1a3/0x240 kernel/trace/bpf_trace.c:1975
       bpf_prog_5c8cb7646b59f521+0x42/0x46
       bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline]
       __bpf_prog_run include/linux/filter.h:657 [inline]
       bpf_prog_run include/linux/filter.h:664 [inline]
       __bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline]
       bpf_trace_run2+0x204/0x420 kernel/trace/bpf_trace.c:2420
       trace_tlb_flush+0xfa/0x120 include/trace/events/tlb.h:38
       switch_mm_irqs_off+0x7cb/0xae0
       context_switch kernel/sched/core.c:5393 [inline]
       __schedule+0x1054/0x4a20 kernel/sched/core.c:6736
       __schedule_loop kernel/sched/core.c:6813 [inline]
       schedule+0x14b/0x320 kernel/sched/core.c:6828
       exit_to_user_mode_loop kernel/entry/common.c:96 [inline]
       exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
       irqentry_exit_to_user_mode+0xe7/0x270 kernel/entry/common.c:225
       asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702

other info that might help us debug this:

Chain exists of:
  lock#10 --> &p->pi_lock --> &rq->__lock

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&rq->__lock);
                               lock(&p->pi_lock);
                               lock(&rq->__lock);
  lock(lock#10);

 *** DEADLOCK ***

2 locks held by syz-executor.2/5452:
 #0: ffff8880b953e158 (&rq->__lock){-.-.}-{2:2}, at: raw_spin_rq_lock_nested+0x2a/0x140 kernel/sched/core.c:559
 #1: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_lock_acquire include/linux/rcupdate.h:298 [inline]
 #1: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: rcu_read_lock include/linux/rcupdate.h:750 [inline]
 #1: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: __bpf_trace_run kernel/trace/bpf_trace.c:2380 [inline]
 #1: ffffffff8e131920 (rcu_read_lock){....}-{1:2}, at: bpf_trace_run2+0x114/0x420 kernel/trace/bpf_trace.c:2420

stack backtrace:
CPU: 1 PID: 5452 Comm: syz-executor.2 Not tainted 6.8.0-syzkaller-05236-g443574b03387 #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+0x1e7/0x2e0 lib/dump_stack.c:106
 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
 local_lock_acquire include/linux/local_lock_internal.h:29 [inline]
 __mmap_lock_do_trace_start_locking+0x9c/0x5f0 mm/mmap_lock.c:230
 __mmap_lock_trace_start_locking include/linux/mmap_lock.h:29 [inline]
 mmap_read_trylock include/linux/mmap_lock.h:164 [inline]
 stack_map_get_build_id_offset+0x98d/0x9d0 kernel/bpf/stackmap.c:141
 __bpf_get_stack+0x4ad/0x5a0 kernel/bpf/stackmap.c:449
 ____bpf_get_stack_raw_tp kernel/trace/bpf_trace.c:1985 [inline]
 bpf_get_stack_raw_tp+0x1a3/0x240 kernel/trace/bpf_trace.c:1975
 bpf_prog_5c8cb7646b59f521+0x42/0x46
 bpf_dispatcher_nop_func include/linux/bpf.h:1234 [inline]
 __bpf_prog_run include/linux/filter.h:657 [inline]
 bpf_prog_run include/linux/filter.h:664 [inline]
 __bpf_trace_run kernel/trace/bpf_trace.c:2381 [inline]
 bpf_trace_run2+0x204/0x420 kernel/trace/bpf_trace.c:2420
 trace_tlb_flush+0xfa/0x120 include/trace/events/tlb.h:38
 switch_mm_irqs_off+0x7cb/0xae0
 context_switch kernel/sched/core.c:5393 [inline]
 __schedule+0x1054/0x4a20 kernel/sched/core.c:6736
 __schedule_loop kernel/sched/core.c:6813 [inline]
 schedule+0x14b/0x320 kernel/sched/core.c:6828
 exit_to_user_mode_loop kernel/entry/common.c:96 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 irqentry_exit_to_user_mode+0xe7/0x270 kernel/entry/common.c:225
 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0033:0x7fe38f639ba5
Code: Unable to access opcode bytes at 0x7fe38f639b7b.
RSP: 002b:00007ffe0d7da5f0 EFLAGS: 00000a87
RAX: 00000000984f6378 RBX: 00007fe38f7ac018 RCX: 0000000000000415
RDX: ffffffff81408dcc RSI: 0000000080000000 RDI: 00000000984f6378
RBP: 0000000081408000 R08: 0000001b31220000 R09: 0000000000000dcd
R10: 0000000081372dd1 R11: 0000000000000000 R12: 0000000000000415
R13: 0000000000000001 R14: 00007fe38f7a0000 R15: ffffffff81408dcc
 </TASK>

---
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