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Date:   Thu, 27 Jul 2023 07:51:16 +0300
From:   Dan Carpenter <dan.carpenter@linaro.org>
To:     oe-kbuild@lists.linux.dev, Helge Deller <deller@gmx.de>,
        Marco Elver <elver@google.com>
Cc:     lkp@intel.com, oe-kbuild-all@lists.linux.dev,
        linux-kernel@vger.kernel.org
Subject: mm/kfence/kfence_test.c:287 test_alloc() warn: use 'gfp' here
 instead of GFP_KERNEL?
Message-ID: <9e72b7ea-9598-415d-bc55-f2f42b7fcb3b@kadam.mountain>
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Hi Helge,

FYI, the error/warning was bisected to this commit, please ignore it if it's irrelevant.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   18b44bc5a67275641fb26f2c54ba7eef80ac5950
commit: adf8e96a7ea670d45b5de7594acc67e8f4787ae6 parisc: Enable LOCKDEP support
config: parisc-randconfig-m041-20230726 (https://download.01.org/0day-ci/archive/20230727/202307270305.L19EfaJD-lkp@intel.com/config)
compiler: hppa-linux-gcc (GCC) 12.3.0
reproduce: (https://download.01.org/0day-ci/archive/20230727/202307270305.L19EfaJD-lkp@intel.com/reproduce)

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 <dan.carpenter@linaro.org>
| Closes: https://lore.kernel.org/r/202307270305.L19EfaJD-lkp@intel.com/

smatch warnings:
mm/kfence/kfence_test.c:287 test_alloc() warn: use 'gfp' here instead of GFP_KERNEL?

(Just included these for the LOLs)
mm/kfence/kfence_test.c:395 test_double_free() error: double free of 'expect.addr'
mm/kfence/kfence_test.c:671 test_memcache_typesafe_by_rcu() error: dereferencing freed memory 'expect.addr'

vim +/gfp +287 mm/kfence/kfence_test.c

bc8fbc5f305aec Marco Elver     2021-02-25  243  static void *test_alloc(struct kunit *test, size_t size, gfp_t gfp, enum allocation_policy policy)
bc8fbc5f305aec Marco Elver     2021-02-25  244  {
bc8fbc5f305aec Marco Elver     2021-02-25  245  	void *alloc;
bc8fbc5f305aec Marco Elver     2021-02-25  246  	unsigned long timeout, resched_after;
bc8fbc5f305aec Marco Elver     2021-02-25  247  	const char *policy_name;
bc8fbc5f305aec Marco Elver     2021-02-25  248  
bc8fbc5f305aec Marco Elver     2021-02-25  249  	switch (policy) {
bc8fbc5f305aec Marco Elver     2021-02-25  250  	case ALLOCATE_ANY:
bc8fbc5f305aec Marco Elver     2021-02-25  251  		policy_name = "any";
bc8fbc5f305aec Marco Elver     2021-02-25  252  		break;
bc8fbc5f305aec Marco Elver     2021-02-25  253  	case ALLOCATE_LEFT:
bc8fbc5f305aec Marco Elver     2021-02-25  254  		policy_name = "left";
bc8fbc5f305aec Marco Elver     2021-02-25  255  		break;
bc8fbc5f305aec Marco Elver     2021-02-25  256  	case ALLOCATE_RIGHT:
bc8fbc5f305aec Marco Elver     2021-02-25  257  		policy_name = "right";
bc8fbc5f305aec Marco Elver     2021-02-25  258  		break;
bc8fbc5f305aec Marco Elver     2021-02-25  259  	case ALLOCATE_NONE:
bc8fbc5f305aec Marco Elver     2021-02-25  260  		policy_name = "none";
bc8fbc5f305aec Marco Elver     2021-02-25  261  		break;
bc8fbc5f305aec Marco Elver     2021-02-25  262  	}
bc8fbc5f305aec Marco Elver     2021-02-25  263  
bc8fbc5f305aec Marco Elver     2021-02-25  264  	kunit_info(test, "%s: size=%zu, gfp=%x, policy=%s, cache=%i\n", __func__, size, gfp,
bc8fbc5f305aec Marco Elver     2021-02-25  265  		   policy_name, !!test_cache);
bc8fbc5f305aec Marco Elver     2021-02-25  266  
bc8fbc5f305aec Marco Elver     2021-02-25  267  	/*
bc8fbc5f305aec Marco Elver     2021-02-25  268  	 * 100x the sample interval should be more than enough to ensure we get
bc8fbc5f305aec Marco Elver     2021-02-25  269  	 * a KFENCE allocation eventually.
bc8fbc5f305aec Marco Elver     2021-02-25  270  	 */
8913c610014823 Peng Liu        2022-02-11  271  	timeout = jiffies + msecs_to_jiffies(100 * kfence_sample_interval);
bc8fbc5f305aec Marco Elver     2021-02-25  272  	/*
bc8fbc5f305aec Marco Elver     2021-02-25  273  	 * Especially for non-preemption kernels, ensure the allocation-gate
bc8fbc5f305aec Marco Elver     2021-02-25  274  	 * timer can catch up: after @resched_after, every failed allocation
bc8fbc5f305aec Marco Elver     2021-02-25  275  	 * attempt yields, to ensure the allocation-gate timer is scheduled.
bc8fbc5f305aec Marco Elver     2021-02-25  276  	 */
8913c610014823 Peng Liu        2022-02-11  277  	resched_after = jiffies + msecs_to_jiffies(kfence_sample_interval);
bc8fbc5f305aec Marco Elver     2021-02-25  278  	do {
bc8fbc5f305aec Marco Elver     2021-02-25  279  		if (test_cache)
bc8fbc5f305aec Marco Elver     2021-02-25  280  			alloc = kmem_cache_alloc(test_cache, gfp);
bc8fbc5f305aec Marco Elver     2021-02-25  281  		else
bc8fbc5f305aec Marco Elver     2021-02-25  282  			alloc = kmalloc(size, gfp);
                                                                                              ^^^

bc8fbc5f305aec Marco Elver     2021-02-25  283  
bc8fbc5f305aec Marco Elver     2021-02-25  284  		if (is_kfence_address(alloc)) {
8dae0cfed57357 Vlastimil Babka 2021-11-03  285  			struct slab *slab = virt_to_slab(alloc);
588c7fa022d7b2 Hyeonggon Yoo   2021-06-28  286  			struct kmem_cache *s = test_cache ?:
588c7fa022d7b2 Hyeonggon Yoo   2021-06-28 @287  					kmalloc_caches[kmalloc_type(GFP_KERNEL)][__kmalloc_index(size, false)];
                                                                                                                    ^^^^^^^^^^
I feel like using gfp might be correct but I'm not sure?  This code
is from prior to this commit.  Let's add Marco to the CC.

bc8fbc5f305aec Marco Elver     2021-02-25  288  
bc8fbc5f305aec Marco Elver     2021-02-25  289  			/*
bc8fbc5f305aec Marco Elver     2021-02-25  290  			 * Verify that various helpers return the right values
bc8fbc5f305aec Marco Elver     2021-02-25  291  			 * even for KFENCE objects; these are required so that
bc8fbc5f305aec Marco Elver     2021-02-25  292  			 * memcg accounting works correctly.
bc8fbc5f305aec Marco Elver     2021-02-25  293  			 */
8dae0cfed57357 Vlastimil Babka 2021-11-03  294  			KUNIT_EXPECT_EQ(test, obj_to_index(s, slab, alloc), 0U);
8dae0cfed57357 Vlastimil Babka 2021-11-03  295  			KUNIT_EXPECT_EQ(test, objs_per_slab(s, slab), 1);
bc8fbc5f305aec Marco Elver     2021-02-25  296  
bc8fbc5f305aec Marco Elver     2021-02-25  297  			if (policy == ALLOCATE_ANY)
bc8fbc5f305aec Marco Elver     2021-02-25  298  				return alloc;
f403f22f8ccb12 Kefeng Wang     2022-05-20  299  			if (policy == ALLOCATE_LEFT && PAGE_ALIGNED(alloc))
bc8fbc5f305aec Marco Elver     2021-02-25  300  				return alloc;
f403f22f8ccb12 Kefeng Wang     2022-05-20  301  			if (policy == ALLOCATE_RIGHT && !PAGE_ALIGNED(alloc))
bc8fbc5f305aec Marco Elver     2021-02-25  302  				return alloc;
bc8fbc5f305aec Marco Elver     2021-02-25  303  		} else if (policy == ALLOCATE_NONE)
bc8fbc5f305aec Marco Elver     2021-02-25  304  			return alloc;
bc8fbc5f305aec Marco Elver     2021-02-25  305  
bc8fbc5f305aec Marco Elver     2021-02-25  306  		test_free(alloc);
bc8fbc5f305aec Marco Elver     2021-02-25  307  
bc8fbc5f305aec Marco Elver     2021-02-25  308  		if (time_after(jiffies, resched_after))
bc8fbc5f305aec Marco Elver     2021-02-25  309  			cond_resched();
bc8fbc5f305aec Marco Elver     2021-02-25  310  	} while (time_before(jiffies, timeout));
bc8fbc5f305aec Marco Elver     2021-02-25  311  
bc8fbc5f305aec Marco Elver     2021-02-25  312  	KUNIT_ASSERT_TRUE_MSG(test, false, "failed to allocate from KFENCE");
bc8fbc5f305aec Marco Elver     2021-02-25  313  	return NULL; /* Unreachable. */
bc8fbc5f305aec Marco Elver     2021-02-25  314  }

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