linux-kernel - kernel/rcu/refscale.c:614:24: sparse: sparse: incompatible types in comparison expression (different address spaces):

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Date:   Fri, 24 Feb 2023 22:12:43 +0800
From:   kernel test robot <lkp@...el.com>
To:     "Paul E. McKenney" <paulmck@...nel.org>
Cc:     oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: kernel/rcu/refscale.c:614:24: sparse: sparse: incompatible types in
 comparison expression (different address spaces):

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   d2980d8d826554fa6981d621e569a453787472f8
commit: a6889becb05394255c80b62103677e3b095726a9 refscale: Add tests using SLAB_TYPESAFE_BY_RCU
date:   7 weeks ago
config: parisc-randconfig-s052-20230222 (https://download.01.org/0day-ci/archive/20230224/202302242216.C9zAq2tw-lkp@intel.com/config)
compiler: hppa-linux-gcc (GCC) 12.1.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # apt-get install sparse
        # sparse version: v0.6.4-39-gce1a6720-dirty
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a6889becb05394255c80b62103677e3b095726a9
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout a6889becb05394255c80b62103677e3b095726a9
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=parisc olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=parisc SHELL=/bin/bash kernel/rcu/

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@...el.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202302242216.C9zAq2tw-lkp@intel.com/

sparse warnings: (new ones prefixed by >>)
>> kernel/rcu/refscale.c:614:24: sparse: sparse: incompatible types in comparison expression (different address spaces):
>> kernel/rcu/refscale.c:614:24: sparse:    struct refscale_typesafe [noderef] __rcu *
>> kernel/rcu/refscale.c:614:24: sparse:    struct refscale_typesafe *
   kernel/rcu/refscale.c:569:13: sparse: sparse: context imbalance in 'typesafe_lock_acquire' - wrong count at exit
   kernel/rcu/refscale.c:576:13: sparse: sparse: context imbalance in 'typesafe_lock_release' - unexpected unlock

vim +614 kernel/rcu/refscale.c

   595	
   596	// Do a read-side critical section with the specified delay in
   597	// microseconds and nanoseconds inserted so as to increase probability
   598	// of failure.
   599	static void typesafe_delay_section(const int nloops, const int udl, const int ndl)
   600	{
   601		unsigned int a;
   602		unsigned int b;
   603		int i;
   604		long idx;
   605		struct refscale_typesafe *rtsp;
   606		unsigned int start;
   607	
   608		for (i = nloops; i >= 0; i--) {
   609			preempt_disable();
   610			idx = torture_random(this_cpu_ptr(&refscale_rand)) % rtsarray_size;
   611			preempt_enable();
   612	retry:
   613			rcu_read_lock();
 > 614			rtsp = rcu_dereference(rtsarray[idx]);
   615			a = READ_ONCE(rtsp->a);
   616			if (!rts_acquire(rtsp, &start)) {
   617				rcu_read_unlock();
   618				goto retry;
   619			}
   620			if (a != READ_ONCE(rtsp->a)) {
   621				(void)rts_release(rtsp, start);
   622				rcu_read_unlock();
   623				goto retry;
   624			}
   625			un_delay(udl, ndl);
   626			// Remember, seqlock read-side release can fail.
   627			if (!rts_release(rtsp, start)) {
   628				rcu_read_unlock();
   629				goto retry;
   630			}
   631			b = READ_ONCE(rtsp->a);
   632			WARN_ONCE(a != b, "Re-read of ->a changed from %u to %u.\n", a, b);
   633			b = rtsp->b;
   634			rcu_read_unlock();
   635			WARN_ON_ONCE(a * a != b);
   636		}
   637	}
   638	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests