linux-kernel - Re: [syzbot] [xfs?] [mm?] WARNING: bad unlock balance in __mm

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Message-ID: <67c7a60d.050a0220.15b4b9.001a.GAE@google.com>
Date: Tue, 04 Mar 2025 17:17:01 -0800
From: syzbot <syzbot+8f9f411152c9539f4e59@...kaller.appspotmail.com>
To: eadavis@...com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [xfs?] [mm?] WARNING: bad unlock balance in __mm_populate

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
WARNING: bad unlock balance in __mm_populate

mm2: 00000000b643f24a, map held lock: 0, vma: 00000000ff43f796, ret: -14, __get_user_pages
mm: 00000000b643f24a, vma: 00000000ff43f796, mmap lock held: 0, locked: 1, ret: -14, mm addr is valid: 1, __mm_populate
=====================================
WARNING: bad unlock balance detected!
6.14.0-rc4-syzkaller-ge056da87c780-dirty #0 Not tainted
-------------------------------------
syz.0.16/7207 is trying to release lock (&mm->mmap_lock) at:
[<ffff800080a640f0>] mmap_read_unlock include/linux/mmap_lock.h:217 [inline]
[<ffff800080a640f0>] __mm_populate+0x4e0/0x590 mm/gup.c:2055
but there are no more locks to release!

other info that might help us debug this:
no locks held by syz.0.16/7207.

stack backtrace:
CPU: 1 UID: 0 PID: 7207 Comm: syz.0.16 Not tainted 6.14.0-rc4-syzkaller-ge056da87c780-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
Call trace:
 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:466 (C)
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0xe4/0x150 lib/dump_stack.c:120
 dump_stack+0x1c/0x28 lib/dump_stack.c:129
 print_unlock_imbalance_bug+0x254/0x2ac kernel/locking/lockdep.c:5289
 __lock_release kernel/locking/lockdep.c:5518 [inline]
 lock_release+0x410/0x9e4 kernel/locking/lockdep.c:5872
 up_read+0x24/0x3c kernel/locking/rwsem.c:1619
 mmap_read_unlock include/linux/mmap_lock.h:217 [inline]
 __mm_populate+0x4e0/0x590 mm/gup.c:2055
 mm_populate include/linux/mm.h:3386 [inline]
 vm_mmap_pgoff+0x304/0x3c4 mm/util.c:580
 ksys_mmap_pgoff+0x3a4/0x5c8 mm/mmap.c:607
 __do_sys_mmap arch/arm64/kernel/sys.c:28 [inline]
 __se_sys_mmap arch/arm64/kernel/sys.c:21 [inline]
 __arm64_sys_mmap+0xf8/0x110 arch/arm64/kernel/sys.c:21
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
------------[ cut here ]------------
DEBUG_RWSEMS_WARN_ON(tmp < 0): count = 0xffffffffffffff00, magic = 0xffff0000d9a82be0, owner = 0x1, curr 0xffff0000ca89bd00, list empty
WARNING: CPU: 1 PID: 7207 at kernel/locking/rwsem.c:1346 __up_read+0x3bc/0x5f8 kernel/locking/rwsem.c:1346
Modules linked in:
CPU: 1 UID: 0 PID: 7207 Comm: syz.0.16 Not tainted 6.14.0-rc4-syzkaller-ge056da87c780-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __up_read+0x3bc/0x5f8 kernel/locking/rwsem.c:1346
lr : __up_read+0x3bc/0x5f8 kernel/locking/rwsem.c:1346
sp : ffff80009d6379c0
x29: ffff80009d637a40
 x28: 1ffff00011f780cb x27: ffff80008fbc0000
x26: dfff800000000000 x25: ffffffffffffff00 x24: ffff0000d9a82c38
x23: ffff0000d9a82be0
 x22: ffffffffffffff00
 x21: 0000000000000001
x20: ffff0000ca89bd00 x19: ffff0000d9a82be0 x18: ffff80009d637288
x17: 0000000000000000
 x16: ffff80008b7c56dc
 x15: 0000000000000001
x14: 1ffff00011f8fe00 x13: ffff80009d638000 x12: ffff80009d637490
x11: 0000000000000003 x10: 0000000000ff0100 x9 : ab50c55cae2af500
x8 : ab50c55cae2af500 x7 : 205b5d3439343135 x6 : ffff8000804a97f4
x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000
x2 : ffff0000ca89bd00 x1 : 0000000000000001 x0 : 0000000000000000
Call trace:
 __up_read+0x3bc/0x5f8 kernel/locking/rwsem.c:1346 (P)
 up_read+0x2c/0x3c kernel/locking/rwsem.c:1620
 mmap_read_unlock include/linux/mmap_lock.h:217 [inline]
 __mm_populate+0x4e0/0x590 mm/gup.c:2055
 mm_populate include/linux/mm.h:3386 [inline]
 vm_mmap_pgoff+0x304/0x3c4 mm/util.c:580
 ksys_mmap_pgoff+0x3a4/0x5c8 mm/mmap.c:607
 __do_sys_mmap arch/arm64/kernel/sys.c:28 [inline]
 __se_sys_mmap arch/arm64/kernel/sys.c:21 [inline]
 __arm64_sys_mmap+0xf8/0x110 arch/arm64/kernel/sys.c:21
 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline]
 invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49
 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132
 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151
 el0_svc+0x54/0x168 arch/arm64/kernel/entry-common.c:744
 el0t_64_sync_handler+0x84/0x108 arch/arm64/kernel/entry-common.c:762
 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600
irq event stamp: 73577
hardirqs last  enabled at (73577): [<ffff8000803d4c78>] raw_spin_rq_unlock_irq kernel/sched/sched.h:1533 [inline]
hardirqs last  enabled at (73577): [<ffff8000803d4c78>] finish_lock_switch+0xbc/0x1e4 kernel/sched/core.c:5132
hardirqs last disabled at (73576): [<ffff80008b7cfc44>] __schedule+0x2bc/0x257c kernel/sched/core.c:6668
softirqs last  enabled at (73528): [<ffff800080311b48>] softirq_handle_end kernel/softirq.c:407 [inline]
softirqs last  enabled at (73528): [<ffff800080311b48>] handle_softirqs+0xb44/0xd34 kernel/softirq.c:589
softirqs last disabled at (73505): [<ffff800080020dbc>] __do_softirq+0x14/0x20 kernel/softirq.c:595
---[ end trace 0000000000000000 ]---


Tested on:

commit:         e056da87 Merge remote-tracking branch 'will/for-next/p..
git tree:       git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=11809c64580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=d6b7e15dc5b5e776
dashboard link: https://syzkaller.appspot.com/bug?extid=8f9f411152c9539f4e59
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: arm64
patch:          https://syzkaller.appspot.com/x/patch.diff?x=1017bc64580000