Hello, syzbot found the following issue on: HEAD commit: 5be63fc19fca Linux 6.11-rc5 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=15d8b247980000 kernel config: https://syzkaller.appspot.com/x/.config?x=f29704545d454ed3 dashboard link: https://syzkaller.appspot.com/bug?extid=b02bbe0ff80a09a08c1b 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/7bc7510fe41f/non_bootable_disk-5be63fc1.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/64065b3c02ed/vmlinux-5be63fc1.xz kernel image: https://storage.googleapis.com/syzbot-assets/aef4258dcb3f/bzImage-5be63fc1.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+b02bbe0ff80a09a08c1b@xxxxxxxxxxxxxxxxxxxxxxxxx ====================================================== WARNING: possible circular locking dependency detected 6.11.0-rc5-syzkaller #0 Not tainted ------------------------------------------------------ syz.2.1318/10014 is trying to acquire lock: ffff88802b6b2798 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock_killable include/linux/mmap_lock.h:153 [inline] ffff88802b6b2798 (&mm->mmap_lock){++++}-{3:3}, at: get_mmap_lock_carefully mm/memory.c:5878 [inline] ffff88802b6b2798 (&mm->mmap_lock){++++}-{3:3}, at: lock_mm_and_find_vma+0x3a9/0x6a0 mm/memory.c:5929 but task is already holding lock: ffff8880302e8b70 (&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_sys_mmap arch/x86/kernel/sys_x86_64.c:86 [inline] __se_sys_mmap arch/x86/kernel/sys_x86_64.c:79 [inline] __x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:79 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 (&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_sys_io_submit fs/aio.c:2111 [inline] __se_sys_io_submit fs/aio.c:2081 [inline] __x64_sys_io_submit+0x19d/0x330 fs/aio.c:2081 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: 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.2.1318/10014: #0: ffff8880302e87b8 (&sb->s_type->i_mutex_key#25){++++}-{3:3}, at: netfs_start_io_write+0x1f/0x70 fs/netfs/locking.c:118 #1: ffff8880302e8b70 (&ctx->wb_lock){+.+.}-{3:3}, at: netfs_begin_writethrough+0x6c/0x3c0 fs/netfs/write_issue.c:572 stack backtrace: CPU: 1 UID: 0 PID: 10014 Comm: syz.2.1318 Not tainted 6.11.0-rc5-syzkaller #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: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: f7 bc ff 48 39 dd 0f 84 f0 00 00 00 45 31 f6 eb 11 e8 6e f7 bc ff 48 81 c3 00 10 00 00 48 39 eb 74 1d e8 5d f7 bc ff 45 89 f7 <8a> 03 31 ff 44 89 fe 88 44 24 28 e8 8a f9 bc ff 45 85 ff 74 d2 e8 RSP: 0018:ffffc900032d7650 EFLAGS: 00050287 RAX: 0000000000030b60 RBX: 0000000020005000 RCX: ffffc900040f9000 RDX: 0000000000040000 RSI: ffffffff81cd8213 RDI: 0000000000000005 RBP: 0000000020006000 R08: 0000000000000005 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000001000 R13: 0000000020004180 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_sys_io_submit fs/aio.c:2111 [inline] __se_sys_io_submit fs/aio.c:2081 [inline] __x64_sys_io_submit+0x19d/0x330 fs/aio.c:2081 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: 0033:0x7f86fd779e79 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:00007f86fe526038 EFLAGS: 00000246 ORIG_RAX: 00000000000000d1 RAX: ffffffffffffffda RBX: 00007f86fd915f80 RCX: 00007f86fd779e79 RDX: 0000000020000700 RSI: 000000000000140b RDI: 00007f86fe4fe000 RBP: 00007f86fd7e793e R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f86fd915f80 R15: 00007ffe70f66888 </TASK> input: syz0 as /devices/virtual/input/input13 netlink: 'syz.2.1318': attribute type 2 has an invalid length. netlink: 'syz.2.1318': attribute type 1 has an invalid length. ---------------- Code disassembly (best guess), 1 bytes skipped: 0: bc ff 48 39 dd mov $0xdd3948ff,%esp 5: 0f 84 f0 00 00 00 je 0xfb b: 45 31 f6 xor %r14d,%r14d e: eb 11 jmp 0x21 10: e8 6e f7 bc ff call 0xffbcf783 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 5d f7 bc ff call 0xffbcf783 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 8a f9 bc ff call 0xffbcf9c3 39: 45 85 ff test %r15d,%r15d 3c: 74 d2 je 0x10 3e: e8 .byte 0xe8 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup
