[android-common:android12-kiwi-5.10 278/278] arch/x86/kernel/kvm.c:237:2-7: WARNING: NULL check before some freeing functions is not needed.

[android-common:android12-kiwi-5.10 278/278] arch/x86/kernel/kvm.c:237:2-7: WARNING: NULL check before some freeing functions is not needed.

[kernel test robot]

tree:   https://android.googlesource.com/kernel/common android12-kiwi-5.10
head:   ae917b3c7332e08006443a49c261aa97ce703103
commit: 4a9f3a9c28a6966c699b4264b6a3c5aaed21ea3e [278/278] x86/kvm: Alloc dummy async #PF token outside of raw spinlock
config: i386-randconfig-r061-20260903 (https://download.01.org/0day-ci/archive/20260904/202609040016.YQuJJkEC-lkp@intel.com/config)
compiler: gcc-14 (Debian 14.2.0-19) 14.2.0

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>
| Closes: https://lore.kernel.org/oe-kbuild-all/202609040016.YQuJJkEC-lkp@intel.com/

cocci warnings: (new ones prefixed by >>)
>> arch/x86/kernel/kvm.c:237:2-7: WARNING: NULL check before some freeing functions is not needed.

vim +237 arch/x86/kernel/kvm.c

   186	
   187	void kvm_async_pf_task_wake(u32 token)
   188	{
   189		u32 key = hash_32(token, KVM_TASK_SLEEP_HASHBITS);
   190		struct kvm_task_sleep_head *b = &async_pf_sleepers[key];
   191		struct kvm_task_sleep_node *n, *dummy = NULL;
   192	
   193		if (token == ~0) {
   194			apf_task_wake_all();
   195			return;
   196		}
   197	
   198	again:
   199		raw_spin_lock(&b->lock);
   200		n = _find_apf_task(b, token);
   201		if (!n) {
   202			/*
   203			 * Async #PF not yet handled, add a dummy entry for the token.
   204			 * Allocating the token must be down outside of the raw lock
   205			 * as the allocator is preemptible on PREEMPT_RT kernels.
   206			 */
   207			if (!dummy) {
   208				raw_spin_unlock(&b->lock);
   209				dummy = kzalloc(sizeof(*dummy), GFP_KERNEL);
   210	
   211				/*
   212				 * Continue looping on allocation failure, eventually
   213				 * the async #PF will be handled and allocating a new
   214				 * node will be unnecessary.
   215				 */
   216				if (!dummy)
   217					cpu_relax();
   218	
   219				/*
   220				 * Recheck for async #PF completion before enqueueing
   221				 * the dummy token to avoid duplicate list entries.
   222				 */
   223				goto again;
   224			}
   225			dummy->token = token;
   226			dummy->cpu = smp_processor_id();
   227			init_swait_queue_head(&dummy->wq);
   228			hlist_add_head(&dummy->link, &b->list);
   229			dummy = NULL;
   230		} else {
   231			apf_task_wake_one(n);
   232		}
   233		raw_spin_unlock(&b->lock);
   234	
   235		/* A dummy token might be allocated and ultimately not used.  */
   236		if (dummy)
 > 237			kfree(dummy);
   238	}
   239	EXPORT_SYMBOL_GPL(kvm_async_pf_task_wake);
   240	

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