[android-common:android-4.9-o-release 44/53] fs/eventpoll.c:528:17: sparse: sparse: incompatible types in comparison expression (different address spaces):

[android-common:android-4.9-o-release 44/53] fs/eventpoll.c:528:17: sparse: sparse: incompatible types in comparison expression (different address spaces):

[kbuild test robot]

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Hi Josh,

First bad commit (maybe != root cause):

tree:   https://android.googlesource.com/kernel/common android-4.9-o-release
head:   a493de2ff342b94623e9241ba0b7926be9c09693
commit: 2d1579e6534c17bac9e927d85fe5d76b7c95b3ad [44/53] objtool, perf: Fix GCC 8 -Wrestrict error
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.1-129-g341daf20-dirty
        git checkout 2d1579e6534c17bac9e927d85fe5d76b7c95b3ad
        make ARCH=x86_64 allmodconfig
        make C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__'

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>


sparse warnings: (new ones prefixed by >>)

>> fs/eventpoll.c:528:17: sparse: sparse: incompatible types in comparison expression (different address spaces):
>> fs/eventpoll.c:528:17: sparse:    struct __wait_queue_head [noderef] <asn:4> *
>> fs/eventpoll.c:528:17: sparse:    struct __wait_queue_head [usertype] *

vim +528 fs/eventpoll.c

^1da177e4c3f41 Linus Torvalds 2005-04-16  521  
971316f0503a5c Oleg Nesterov  2012-02-24  522  static void ep_remove_wait_queue(struct eppoll_entry *pwq)
971316f0503a5c Oleg Nesterov  2012-02-24  523  {
971316f0503a5c Oleg Nesterov  2012-02-24  524  	wait_queue_head_t *whead;
971316f0503a5c Oleg Nesterov  2012-02-24  525  
971316f0503a5c Oleg Nesterov  2012-02-24  526  	rcu_read_lock();
971316f0503a5c Oleg Nesterov  2012-02-24  527  	/* If it is cleared by POLLFREE, it should be rcu-safe */
971316f0503a5c Oleg Nesterov  2012-02-24 @528  	whead = rcu_dereference(pwq->whead);
971316f0503a5c Oleg Nesterov  2012-02-24  529  	if (whead)
971316f0503a5c Oleg Nesterov  2012-02-24  530  		remove_wait_queue(whead, &pwq->wait);
971316f0503a5c Oleg Nesterov  2012-02-24  531  	rcu_read_unlock();
971316f0503a5c Oleg Nesterov  2012-02-24  532  }
971316f0503a5c Oleg Nesterov  2012-02-24  533  

:::::: The code at line 528 was first introduced by commit
:::::: 971316f0503a5c50633d07b83b6db2f15a3a5b00 epoll: ep_unregister_pollwait() can use the freed pwq->whead

:::::: TO: Oleg Nesterov <oleg@redhat.com>
:::::: CC: Linus Torvalds <torvalds@linux-foundation.org>

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