Re: arch/riscv/kvm/../../../virt/kvm/kvm_main.c:1378 kvm_trylock_all_vcpus() warn: iterator 'i' not incremented

[Dan Carpenter <dan.carpenter@linaro.org>]

Hi,

I'm going to be taking a break from reporting Smatch warnings until we
can work out new funding for it.  I'm pretty confident that we will be
able to but there wasn't a lot of notice and everyone was off for the
Holiday Season so we haven't really started the fund raising process.

https://lore.kernel.org/all/aTaiGSbWZ9DJaGo7@stanley.mountain/

I imagine that we should just send these warnings directly, but there
are some which are obvious false positives so I'd like to clean that
up before we start sending unfiltered warnings.

I've never been able to reproduce these warnings "iterator 'i' not
incremented" false positives.  I've tried deleting my cross function
database and using the exact same config and everything I know how to
reproduce them but I can't.  Are you using the latest version of
Smatch?

regards,
dan carpenter

On Sat, Dec 20, 2025 at 03:40:19AM +0800, kernel test robot wrote:
> BCC: lkp@intel.com
> CC: oe-kbuild-all@lists.linux.dev
> CC: linux-kernel@vger.kernel.org
> TO: Maxim Levitsky <mlevitsk@redhat.com>
> CC: Paolo Bonzini <pbonzini@redhat.com>
> 
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head:   dd9b004b7ff3289fb7bae35130c0a5c0537266af
> commit: e4a454ced74c0ac97c8bd32f086ee3ad74528780 KVM: add kvm_lock_all_vcpus and kvm_trylock_all_vcpus
> date:   7 months ago
> :::::: branch date: 22 hours ago
> :::::: commit date: 7 months ago
> config: riscv-randconfig-r073-20251214 (https://download.01.org/0day-ci/archive/20251220/202512200337.um368Um1-lkp@intel.com/config)
> compiler: clang version 22.0.0git (https://github.com/llvm/llvm-project 1335a05ab8bc8339ce24be3a9da89d8c3f4e0571)
> 
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@intel.com>
> | Reported-by: Dan Carpenter <error27@gmail.com>
> | Closes: https://lore.kernel.org/r/202512200337.um368Um1-lkp@intel.com/
> 
> New smatch warnings:
> arch/riscv/kvm/../../../virt/kvm/kvm_main.c:1378 kvm_trylock_all_vcpus() warn: iterator 'i' not incremented
> 
> Old smatch warnings:
> arch/riscv/kvm/../../../virt/kvm/kvm_main.c:283 kvm_make_all_cpus_request() warn: iterator 'i' not incremented
> arch/riscv/kvm/../../../virt/kvm/kvm_main.c:487 kvm_destroy_vcpus() warn: iterator 'i' not incremented
> arch/riscv/kvm/../../../virt/kvm/kvm_main.c:1384 kvm_trylock_all_vcpus() warn: iterator 'j' not incremented
> arch/riscv/kvm/../../../virt/kvm/kvm_main.c:1401 kvm_lock_all_vcpus() warn: iterator 'i' not incremented
> arch/riscv/kvm/../../../virt/kvm/kvm_main.c:1409 kvm_lock_all_vcpus() warn: iterator 'j' not incremented
> arch/riscv/kvm/../../../virt/kvm/kvm_main.c:1425 kvm_unlock_all_vcpus() warn: iterator 'i' not incremented
> arch/riscv/kvm/../../../virt/kvm/kvm_main.c:1721 kvm_commit_memory_region() error: we previously assumed 'old' could be null (see line 1714)
> arch/riscv/kvm/../../../virt/kvm/kvm_main.c:1723 kvm_commit_memory_region() error: we previously assumed 'new' could be null (see line 1715)
> include/linux/kvm_host.h:1010 kvm_get_vcpu_by_id() warn: iterator 'i' not incremented
> arch/riscv/kvm/../../../virt/kvm/kvm_main.c:4961 kvm_vm_ioctl_reset_dirty_pages() warn: iterator 'i' not incremented
> arch/riscv/kvm/../../../virt/kvm/kvm_main.c:6092 kvm_get_stat_per_vcpu() warn: iterator 'i' not incremented
> arch/riscv/kvm/../../../virt/kvm/kvm_main.c:6103 kvm_clear_stat_per_vcpu() warn: iterator 'i' not incremented
> 
> vim +/i +1378 arch/riscv/kvm/../../../virt/kvm/kvm_main.c
> 
> 6aa8b732ca01c3d drivers/kvm/kvm_main.c Avi Kivity     2006-12-10  1370  
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1371  int kvm_trylock_all_vcpus(struct kvm *kvm)
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1372  {
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1373  	struct kvm_vcpu *vcpu;
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1374  	unsigned long i, j;
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1375  
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1376  	lockdep_assert_held(&kvm->lock);
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1377  
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12 @1378  	kvm_for_each_vcpu(i, vcpu, kvm)
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1379  		if (!mutex_trylock_nest_lock(&vcpu->mutex, &kvm->lock))
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1380  			goto out_unlock;
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1381  	return 0;
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1382  
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1383  out_unlock:
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1384  	kvm_for_each_vcpu(j, vcpu, kvm) {
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1385  		if (i == j)
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1386  			break;
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1387  		mutex_unlock(&vcpu->mutex);
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1388  	}
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1389  	return -EINTR;
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1390  }
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1391  EXPORT_SYMBOL_GPL(kvm_trylock_all_vcpus);
> e4a454ced74c0ac virt/kvm/kvm_main.c    Maxim Levitsky 2025-05-12  1392  
> 
> -- 
> 0-DAY CI Kernel Test Service
> https://github.com/intel/lkp-tests/wiki