syzbot

loop0: detected capacity change from 0 to 512
EXT4-fs (loop0): mounted filesystem 00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode: writeback.
ext4 filesystem being mounted at /0/bus supports timestamps until 2038-01-19 (0x7fffffff)
=====================================
WARNING: bad unlock balance detected!
6.14.0-rc6-syzkaller-00016-g0fed89a961ea #0 Not tainted
-------------------------------------
syz.0.0/5317 is trying to release lock (&mm->mmap_lock) at:
[<ffffffff820d25aa>] mmap_read_unlock include/linux/mmap_lock.h:217 [inline]
[<ffffffff820d25aa>] __mm_populate+0x39a/0x460 mm/gup.c:2044
but there are no more locks to release!

other info that might help us debug this:
no locks held by syz.0.0/5317.

stack backtrace:
CPU: 0 UID: 0 PID: 5317 Comm: syz.0.0 Not tainted 6.14.0-rc6-syzkaller-00016-g0fed89a961ea #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:94 [inline]
 dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120
 print_unlock_imbalance_bug+0x25b/0x2d0 kernel/locking/lockdep.c:5289
 __lock_release kernel/locking/lockdep.c:5518 [inline]
 lock_release+0x47e/0xa30 kernel/locking/lockdep.c:5872
 up_read+0x16/0x20 kernel/locking/rwsem.c:1619
 mmap_read_unlock include/linux/mmap_lock.h:217 [inline]
 __mm_populate+0x39a/0x460 mm/gup.c:2044
 mm_populate include/linux/mm.h:3386 [inline]
 vm_mmap_pgoff+0x303/0x430 mm/util.c:580
 ksys_mmap_pgoff+0x4eb/0x720 mm/mmap.c:607
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0765b8d169
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:00007f0766a45038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f0765da5fa0 RCX: 00007f0765b8d169
RDX: 0000000000000002 RSI: 0000000000b36000 RDI: 0000400000000000
RBP: 00007f0765c0e2a0 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000028011 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f0765da5fa0 R15: 00007ffe1855b468
 </TASK>
------------[ cut here ]------------
DEBUG_RWSEMS_WARN_ON(tmp < 0): count = 0xffffffffffffff00, magic = 0xffff88801d1e1570, owner = 0x1, curr 0xffff888000fca440, list empty
WARNING: CPU: 0 PID: 5317 at kernel/locking/rwsem.c:1346 __up_read+0x415/0x6b0 kernel/locking/rwsem.c:1346
Modules linked in:
CPU: 0 UID: 0 PID: 5317 Comm: syz.0.0 Not tainted 6.14.0-rc6-syzkaller-00016-g0fed89a961ea #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:__up_read+0x415/0x6b0 kernel/locking/rwsem.c:1346
Code: d8 48 c7 c7 c0 a7 2a 8c 48 c7 c6 c0 a9 2a 8c 48 8b 54 24 10 4c 89 f9 4d 89 e8 4c 8b 4c 24 08 53 e8 50 8a e5 ff 48 83 c4 08 90 <0f> 0b 90 90 48 bb 00 00 00 00 00 fc ff df e9 7e fe ff ff c6 05 a0
RSP: 0018:ffffc9000d407be0 EFLAGS: 00010292
RAX: d5ce63e66dbaf500 RBX: ffffffff8c2aa8a0 RCX: 0000000000100000
RDX: ffffc9000e6ea000 RSI: 000000000001102d RDI: 000000000001102e
RBP: ffffc9000d407c90 R08: ffffffff81819e52 R09: fffffbfff1d3a69c
R10: dffffc0000000000 R11: fffffbfff1d3a69c R12: ffffffffffffff00
R13: 0000000000000001 R14: 1ffff11003a3c2af R15: ffff88801d1e1570
FS:  00007f0766a456c0(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000558fd7f5dea0 CR3: 0000000036778000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 mmap_read_unlock include/linux/mmap_lock.h:217 [inline]
 __mm_populate+0x39a/0x460 mm/gup.c:2044
 mm_populate include/linux/mm.h:3386 [inline]
 vm_mmap_pgoff+0x303/0x430 mm/util.c:580
 ksys_mmap_pgoff+0x4eb/0x720 mm/mmap.c:607
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f0765b8d169
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:00007f0766a45038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f0765da5fa0 RCX: 00007f0765b8d169
RDX: 0000000000000002 RSI: 0000000000b36000 RDI: 0000400000000000
RBP: 00007f0765c0e2a0 R08: 0000000000000007 R09: 0000000000000000
R10: 0000000000028011 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f0765da5fa0 R15: 00007ffe1855b468
 </TASK>