====================================================== WARNING: possible circular locking dependency detected 6.11.0-rc7-syzkaller-00017-gbc83b4d1f086 #0 Not tainted ------------------------------------------------------ syz.3.3826/20934 is trying to acquire lock: ffff88805635b118 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock_killable include/linux/mmap_lock.h:153 [inline] ffff88805635b118 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5878 [inline] ffff88805635b118 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x3a9/0x6a0 mm/memory.c:5929 but task is already holding lock: ffff88804971bef0 (&ctx->wb_lock){+.+.}-{3:3}, at: netfs_begin_writethrough+0x6c/0x3c0 fs/netfs/write_issue.c:572 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&ctx->wb_lock){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:608 [inline] __mutex_lock+0x175/0x9c0 kernel/locking/mutex.c:752 netfs_writepages+0x5e1/0xdd0 fs/netfs/write_issue.c:509 do_writepages+0x1a3/0x7f0 mm/page-writeback.c:2683 filemap_fdatawrite_wbc mm/filemap.c:397 [inline] filemap_fdatawrite_wbc+0x148/0x1c0 mm/filemap.c:387 v9fs_mmap_vm_close+0x213/0x260 fs/9p/vfs_file.c:502 remove_vma+0x8b/0x180 mm/mmap.c:182 remove_mt mm/mmap.c:2415 [inline] do_vmi_align_munmap+0x1272/0x19c0 mm/mmap.c:2758 do_vmi_munmap+0x231/0x410 mm/mmap.c:2830 mmap_region+0x17f/0x2760 mm/mmap.c:2881 do_mmap+0xbfb/0xfb0 mm/mmap.c:1468 vm_mmap_pgoff+0x1ba/0x360 mm/util.c:588 ksys_mmap_pgoff+0x332/0x5d0 mm/mmap.c:1514 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e -> #0 (&mm->mmap_lock){++++}-{3:3}: check_prev_add kernel/locking/lockdep.c:3133 [inline] check_prevs_add kernel/locking/lockdep.c:3252 [inline] validate_chain kernel/locking/lockdep.c:3868 [inline] __lock_acquire+0x24ed/0x3cb0 kernel/locking/lockdep.c:5142 lock_acquire kernel/locking/lockdep.c:5759 [inline] lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5724 down_read_killable+0x9d/0x380 kernel/locking/rwsem.c:1549 mmap_read_lock_killable include/linux/mmap_lock.h:153 [inline] get_mmap_lock_carefully mm/memory.c:5878 [inline] lock_mm_and_find_vma+0x3a9/0x6a0 mm/memory.c:5929 do_user_addr_fault+0x2b5/0x13f0 arch/x86/mm/fault.c:1361 handle_page_fault arch/x86/mm/fault.c:1481 [inline] exc_page_fault+0x5c/0xc0 arch/x86/mm/fault.c:1539 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 fault_in_readable+0x126/0x230 mm/gup.c:2244 fault_in_iov_iter_readable+0x101/0x2c0 lib/iov_iter.c:94 netfs_perform_write+0x3ef/0x2250 fs/netfs/buffered_write.c:240 netfs_buffered_write_iter_locked+0x213/0x2c0 fs/netfs/buffered_write.c:470 netfs_file_write_iter+0x1e0/0x470 fs/netfs/buffered_write.c:509 v9fs_file_write_iter+0xa1/0x100 fs/9p/vfs_file.c:407 aio_write+0x3c1/0x8e0 fs/aio.c:1633 __io_submit_one fs/aio.c:2005 [inline] io_submit_one+0x124e/0x1db0 fs/aio.c:2052 __do_compat_sys_io_submit fs/aio.c:2153 [inline] __se_compat_sys_io_submit fs/aio.c:2123 [inline] __ia32_compat_sys_io_submit+0x1af/0x390 fs/aio.c:2123 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&ctx->wb_lock); lock(&mm->mmap_lock); lock(&ctx->wb_lock); rlock(&mm->mmap_lock); *** DEADLOCK *** 2 locks held by syz.3.3826/20934: #0: ffff88804971bb38 (&sb->s_type->i_mutex_key#25){++++}-{3:3}, at: netfs_start_io_write+0x1f/0x70 fs/netfs/locking.c:118 #1: ffff88804971bef0 (&ctx->wb_lock){+.+.}-{3:3}, at: netfs_begin_writethrough+0x6c/0x3c0 fs/netfs/write_issue.c:572 stack backtrace: CPU: 2 UID: 0 PID: 20934 Comm: syz.3.3826 Not tainted 6.11.0-rc7-syzkaller-00017-gbc83b4d1f086 #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: __dump_stack lib/dump_stack.c:93 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:119 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2186 check_prev_add kernel/locking/lockdep.c:3133 [inline] check_prevs_add kernel/locking/lockdep.c:3252 [inline] validate_chain kernel/locking/lockdep.c:3868 [inline] __lock_acquire+0x24ed/0x3cb0 kernel/locking/lockdep.c:5142 lock_acquire kernel/locking/lockdep.c:5759 [inline] lock_acquire+0x1b1/0x560 kernel/locking/lockdep.c:5724 down_read_killable+0x9d/0x380 kernel/locking/rwsem.c:1549 mmap_read_lock_killable include/linux/mmap_lock.h:153 [inline] get_mmap_lock_carefully mm/memory.c:5878 [inline] lock_mm_and_find_vma+0x3a9/0x6a0 mm/memory.c:5929 do_user_addr_fault+0x2b5/0x13f0 arch/x86/mm/fault.c:1361 handle_page_fault arch/x86/mm/fault.c:1481 [inline] exc_page_fault+0x5c/0xc0 arch/x86/mm/fault.c:1539 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 RIP: 0010:fault_in_readable+0x126/0x230 mm/gup.c:2244 Code: 77 bb ff 48 39 dd 0f 84 f0 00 00 00 45 31 f6 eb 11 e8 ce 77 bb ff 48 81 c3 00 10 00 00 48 39 eb 74 1d e8 bd 77 bb ff 45 89 f7 <8a> 03 31 ff 44 89 fe 88 44 24 28 e8 ea 79 bb ff 45 85 ff 74 d2 e8 RSP: 0018:ffffc90002fef640 EFLAGS: 00050246 RAX: 0000000000040000 RBX: 000000002002b000 RCX: ffffc90007cb1000 RDX: 0000000000040000 RSI: ffffffff81cfa263 RDI: 0000000000000005 RBP: 000000002002c000 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000001000 R13: 000000002002a339 R14: 0000000000000000 R15: 0000000000000000 fault_in_iov_iter_readable+0x101/0x2c0 lib/iov_iter.c:94 netfs_perform_write+0x3ef/0x2250 fs/netfs/buffered_write.c:240 netfs_buffered_write_iter_locked+0x213/0x2c0 fs/netfs/buffered_write.c:470 netfs_file_write_iter+0x1e0/0x470 fs/netfs/buffered_write.c:509 v9fs_file_write_iter+0xa1/0x100 fs/9p/vfs_file.c:407 aio_write+0x3c1/0x8e0 fs/aio.c:1633 __io_submit_one fs/aio.c:2005 [inline] io_submit_one+0x124e/0x1db0 fs/aio.c:2052 __do_compat_sys_io_submit fs/aio.c:2153 [inline] __se_compat_sys_io_submit fs/aio.c:2123 [inline] __ia32_compat_sys_io_submit+0x1af/0x390 fs/aio.c:2123 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline] __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf743e579 Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00 RSP: 002b:00000000f572656c EFLAGS: 00000296 ORIG_RAX: 00000000000000f8 RAX: ffffffffffffffda RBX: 00000000f56fe000 RCX: 000000000000140b RDX: 0000000020000700 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ---------------- Code disassembly (best guess), 1 bytes skipped: 0: bb ff 48 39 dd mov $0xdd3948ff,%ebx 5: 0f 84 f0 00 00 00 je 0xfb b: 45 31 f6 xor %r14d,%r14d e: eb 11 jmp 0x21 10: e8 ce 77 bb ff call 0xffbb77e3 15: 48 81 c3 00 10 00 00 add $0x1000,%rbx 1c: 48 39 eb cmp %rbp,%rbx 1f: 74 1d je 0x3e 21: e8 bd 77 bb ff call 0xffbb77e3 26: 45 89 f7 mov %r14d,%r15d * 29: 8a 03 mov (%rbx),%al <-- trapping instruction 2b: 31 ff xor %edi,%edi 2d: 44 89 fe mov %r15d,%esi 30: 88 44 24 28 mov %al,0x28(%rsp) 34: e8 ea 79 bb ff call 0xffbb7a23 39: 45 85 ff test %r15d,%r15d 3c: 74 d2 je 0x10 3e: e8 .byte 0xe8