============================================ WARNING: possible recursive locking detected 6.1.0-rc4-next-20221111-syzkaller-dirty #0 Not tainted -------------------------------------------- syz-executor.0/5772 is trying to acquire lock: ffff88807dd89b98 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock_killable include/linux/mmap_lock.h:126 [inline] ffff88807dd89b98 (&mm->mmap_lock){++++}-{3:3}, at: show_map_vma+0x1dd/0x8a0 fs/proc/task_mmu.c:298 but task is already holding lock: ffff88807dd89b98 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock_killable include/linux/mmap_lock.h:126 [inline] ffff88807dd89b98 (&mm->mmap_lock){++++}-{3:3}, at: m_start+0x1d6/0x670 fs/proc/task_mmu.c:162 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&mm->mmap_lock); lock(&mm->mmap_lock); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by syz-executor.0/5772: #0: ffff88801d4c28b8 (&p->lock){+.+.}-{3:3}, at: seq_read_iter+0xdf/0x1280 fs/seq_file.c:182 #1: ffff88807dd89b98 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock_killable include/linux/mmap_lock.h:126 [inline] #1: ffff88807dd89b98 (&mm->mmap_lock){++++}-{3:3}, at: m_start+0x1d6/0x670 fs/proc/task_mmu.c:162 stack backtrace: CPU: 1 PID: 5772 Comm: syz-executor.0 Not tainted 6.1.0-rc4-next-20221111-syzkaller-dirty #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 print_deadlock_bug kernel/locking/lockdep.c:2990 [inline] check_deadlock kernel/locking/lockdep.c:3033 [inline] validate_chain kernel/locking/lockdep.c:3818 [inline] __lock_acquire.cold+0x116/0x3a7 kernel/locking/lockdep.c:5055 lock_acquire kernel/locking/lockdep.c:5668 [inline] lock_acquire+0x1df/0x630 kernel/locking/lockdep.c:5633 down_read_killable+0x9b/0x490 kernel/locking/rwsem.c:1532 mmap_read_lock_killable include/linux/mmap_lock.h:126 [inline] show_map_vma+0x1dd/0x8a0 fs/proc/task_mmu.c:298 show_smap+0xe4/0x490 fs/proc/task_mmu.c:873 traverse.part.0+0xcf/0x5f0 fs/seq_file.c:111 traverse fs/seq_file.c:101 [inline] seq_read_iter+0x90f/0x1280 fs/seq_file.c:195 seq_read+0x16d/0x210 fs/seq_file.c:162 do_loop_readv_writev fs/read_write.c:756 [inline] do_loop_readv_writev fs/read_write.c:743 [inline] do_iter_read+0x4f8/0x750 fs/read_write.c:798 vfs_readv+0xe5/0x150 fs/read_write.c:916 do_preadv fs/read_write.c:1008 [inline] __do_sys_preadv fs/read_write.c:1058 [inline] __se_sys_preadv fs/read_write.c:1053 [inline] __x64_sys_preadv+0x22b/0x310 fs/read_write.c:1053 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fdc27c8b639 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fdc28980168 EFLAGS: 00000246 ORIG_RAX: 0000000000000127 RAX: ffffffffffffffda RBX: 00007fdc27dabf80 RCX: 00007fdc27c8b639 RDX: 0000000000000001 RSI: 00000000200006c0 RDI: 0000000000000003 RBP: 00007fdc27ce67e1 R08: 0000000000000000 R09: 0000000000000000 R10: 00000000fffffffe R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffc20c7d9af R14: 00007fdc28980300 R15: 0000000000022000