R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ============================================ WARNING: possible recursive locking detected 6.13.0-rc3-syzkaller-00044-gaef25be35d23 #0 Not tainted -------------------------------------------- syz.4.2268/14685 is trying to acquire lock: ffff888025cced20 (&mm->mmap_lock){++++}-{4:4}, at: gup_fast_fallback+0x11bf/0x2690 mm/gup.c:3416 but task is already holding lock: ffff888025cced20 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:122 [inline] ffff888025cced20 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x160/0x360 mm/util.c:578 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.4.2268/14685: #0: ffff888025cced20 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:122 [inline] #0: ffff888025cced20 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x160/0x360 mm/util.c:578 #1: ffff88804e265f20 (&ctx->wb_lock){+.+.}-{4:4}, at: netfs_writepages+0xb9/0x8f0 fs/netfs/write_issue.c:546 stack backtrace: CPU: 2 UID: 0 PID: 14685 Comm: syz.4.2268 Not tainted 6.13.0-rc3-syzkaller-00044-gaef25be35d23 #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:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_deadlock_bug+0x2e3/0x410 kernel/locking/lockdep.c:3037 check_deadlock kernel/locking/lockdep.c:3089 [inline] validate_chain kernel/locking/lockdep.c:3891 [inline] __lock_acquire+0x2117/0x3c40 kernel/locking/lockdep.c:5226 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849 gup_fast_fallback+0x11f8/0x2690 mm/gup.c:3416 get_user_pages_fast+0xa8/0x100 mm/gup.c:3512 __iov_iter_get_pages_alloc+0x8ed/0x2280 lib/iov_iter.c:1177 iov_iter_get_pages_alloc2+0x53/0xf0 lib/iov_iter.c:1230 p9_get_mapped_pages.part.0.constprop.0+0x4ca/0x7d0 net/9p/trans_virtio.c:333 p9_get_mapped_pages net/9p/trans_virtio.c:318 [inline] p9_virtio_zc_request+0x1ac/0x1460 net/9p/trans_virtio.c:439 p9_client_zc_rpc.constprop.0+0x29a/0x880 net/9p/client.c:808 p9_client_write+0x447/0x680 net/9p/client.c:1641 v9fs_issue_write+0xe2/0x180 fs/9p/vfs_addr.c:59 netfs_do_issue_write+0x92/0x110 fs/netfs/write_issue.c:233 netfs_issue_write fs/netfs/write_issue.c:260 [inline] netfs_end_issue_write+0x145/0x1f0 fs/netfs/write_issue.c:528 netfs_writepages+0x627/0x8f0 fs/netfs/write_issue.c:586 do_writepages+0x1b3/0x820 mm/page-writeback.c:2702 filemap_fdatawrite_wbc mm/filemap.c:397 [inline] filemap_fdatawrite_wbc+0x104/0x160 mm/filemap.c:387 v9fs_mmap_vm_close+0x1ff/0x250 fs/9p/vfs_file.c:502 vma_close mm/internal.h:147 [inline] vms_clean_up_area mm/vma.c:1158 [inline] __mmap_prepare mm/vma.c:2278 [inline] __mmap_region+0x5a4/0x2670 mm/vma.c:2443 mmap_region+0x127/0x320 mm/mmap.c:1348 do_mmap+0xc00/0xfc0 mm/mmap.c:496 vm_mmap_pgoff+0x1ba/0x360 mm/util.c:580 ksys_mmap_pgoff+0x32c/0x5c0 mm/mmap.c:542 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: 0023:0xf7fef579 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:00000000f514655c EFLAGS: 00000296 ORIG_RAX: 00000000000000c0 RAX: ffffffffffffffda RBX: 0000000020000000 RCX: 0000000000007000 RDX: 0000000000000000 RSI: 0000000000097052 RDI: 0000000000000006 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ---------------- Code disassembly (best guess), 2 bytes skipped: 0: 10 06 adc %al,(%rsi) 2: 03 74 b4 01 add 0x1(%rsp,%rsi,4),%esi 6: 10 07 adc %al,(%rdi) 8: 03 74 b0 01 add 0x1(%rax,%rsi,4),%esi c: 10 08 adc %cl,(%rax) e: 03 74 d8 01 add 0x1(%rax,%rbx,8),%esi 1e: 00 51 52 add %dl,0x52(%rcx) 21: 55 push %rbp 22: 89 e5 mov %esp,%ebp 24: 0f 34 sysenter 26: cd 80 int $0x80 * 28: 5d pop %rbp <-- trapping instruction 29: 5a pop %rdx 2a: 59 pop %rcx 2b: c3 ret 2c: 90 nop 2d: 90 nop 2e: 90 nop 2f: 90 nop 30: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi 37: 8d b4 26 00 00 00 00 lea 0x0(%rsi,%riz,1),%esi