Re: [rcu:urezki-pcount.2020.09.26a 17/17] kernel/rcu/tree.c:3315:52: sparse: sparse: incorrect type in argument 2 (different base types)

["Paul E. McKenney" <paulmck@kernel.org>]

On Sun, Sep 27, 2020 at 06:55:31AM +0800, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git urezki-pcount.2020.09.26a
> head:   e9bed2a1239b017d78cec5de66adce0560f6d077
> commit: e9bed2a1239b017d78cec5de66adce0560f6d077 [17/17] kvfree_rcu(): Switch to kmalloc() and kfree() for allocations
> config: i386-randconfig-s002-20200927 (attached as .config)
> compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
> reproduce:
>         # apt-get install sparse
>         # sparse version: v0.6.2-201-g24bdaac6-dirty
>         # https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/commit/?id=e9bed2a1239b017d78cec5de66adce0560f6d077
>         git remote add rcu https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
>         git fetch --no-tags rcu urezki-pcount.2020.09.26a
>         git checkout e9bed2a1239b017d78cec5de66adce0560f6d077
>         # save the attached .config to linux build tree
>         make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=i386 
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>

Fixed by 1a8eee1cc5b0 ("squash! kvfree_rcu: Switch to GFP_ATOMIC when
preemption is enabled"), to be squashed into the original.

Thank you for your testing efforts!

							Thanx, Paul

> sparse warnings: (new ones prefixed by >>)
> 
>    kernel/rcu/tree.c:1344:13: sparse: sparse: context imbalance in 'rcu_start_this_gp' - different lock contexts for basic block
>    kernel/rcu/tree.c:1787:9: sparse: sparse: context imbalance in 'rcu_gp_init' - different lock contexts for basic block
>    kernel/rcu/tree.c:2542:9: sparse: sparse: context imbalance in 'force_qs_rnp' - different lock contexts for basic block
>    kernel/rcu/tree.c:2596:25: sparse: sparse: context imbalance in 'rcu_force_quiescent_state' - unexpected unlock
>    kernel/rcu/tree.c:3299:29: sparse: sparse: incorrect type in initializer (different base types) @@     expected int gfp @@     got restricted gfp_t @@
>    kernel/rcu/tree.c:3299:29: sparse:     expected int gfp
>    kernel/rcu/tree.c:3299:29: sparse:     got restricted gfp_t
> >> kernel/rcu/tree.c:3315:52: sparse: sparse: incorrect type in argument 2 (different base types) @@     expected restricted gfp_t [usertype] flags @@     got int gfp @@
> >> kernel/rcu/tree.c:3315:52: sparse:     expected restricted gfp_t [usertype] flags
>    kernel/rcu/tree.c:3315:52: sparse:     got int gfp
>    kernel/rcu/tree.c: note: in included file:
>    kernel/rcu/tree_stall.h:749:17: sparse: sparse: context imbalance in 'rcu_check_gp_start_stall' - different lock contexts for basic block
>    kernel/rcu/tree.c: note: in included file:
>    kernel/rcu/tree_exp.h:189:9: sparse: sparse: context imbalance in '__rcu_report_exp_rnp' - different lock contexts for basic block
> 
> vim +3315 kernel/rcu/tree.c
> 
>   3292	
>   3293	static inline bool
>   3294	add_ptr_to_bulk_krc_lock(struct kfree_rcu_cpu **krcp,
>   3295		unsigned long *flags, void *ptr, bool can_sleep)
>   3296	{
>   3297		struct kvfree_rcu_bulk_data *bnode;
>   3298		bool can_alloc_page = preemptible();
>   3299		int gfp = can_sleep ? GFP_NOWAIT | __GFP_NOWARN : GFP_ATOMIC;
>   3300		int idx;
>   3301	
>   3302		*krcp = krc_this_cpu_lock(flags);
>   3303		if (unlikely(!(*krcp)->initialized))
>   3304			return false;
>   3305	
>   3306		idx = !!is_vmalloc_addr(ptr);
>   3307	
>   3308		/* Check if a new block is required. */
>   3309		if (!(*krcp)->bkvhead[idx] ||
>   3310				(*krcp)->bkvhead[idx]->nr_records == KVFREE_BULK_MAX_ENTR) {
>   3311			bnode = get_cached_bnode(*krcp);
>   3312			if (!bnode && can_alloc_page) {
>   3313				migrate_disable();
>   3314				krc_this_cpu_unlock(*krcp, *flags);
> > 3315				bnode = kmalloc(PAGE_SIZE, gfp);
>   3316				*krcp = krc_this_cpu_lock(flags);
>   3317				migrate_enable();
>   3318			}
>   3319	
>   3320			/* Switch to emergency path. */
>   3321			if (unlikely(!bnode))
>   3322				return false;
>   3323	
>   3324			/* Initialize the new block. */
>   3325			bnode->nr_records = 0;
>   3326			bnode->next = (*krcp)->bkvhead[idx];
>   3327	
>   3328			/* Attach it to the head. */
>   3329			(*krcp)->bkvhead[idx] = bnode;
>   3330		}
>   3331	
>   3332		/* Finally insert. */
>   3333		(*krcp)->bkvhead[idx]->records
>   3334			[(*krcp)->bkvhead[idx]->nr_records++] = ptr;
>   3335	
>   3336		return true;
>   3337	}
>   3338	
> 
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org