tree: https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git locking/kcsan head: ffed638b6a2180da8fd002a46632d746af72b299 commit: bbfa112b46bdbbdfc2f5bfb9c2dcbef780ff6417 [12/21] READ_ONCE: Simplify implementations of {READ,WRITE}_ONCE() reproduce: # apt-get install sparse # sparse version: v0.6.1-193-gb8fad4bc-dirty git checkout bbfa112b46bdbbdfc2f5bfb9c2dcbef780ff6417 make ARCH=x86_64 allmodconfig make C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' If you fix the issue, kindly add following tag as appropriate Reported-by: kbuild test robot <lkp(a)intel.com&gt; sparse warnings: (new ones prefixed by >>) net/netfilter/core.c:585:26: sparse: got void ( *[noderef] <asn:4> * )( ... ) net/netfilter/core.c:585:26: sparse: sparse: incompatible types in comparison expression (different address spaces): net/netfilter/core.c:585:26: sparse: void ( [noderef] <asn:4> * )( ... ) net/netfilter/core.c:585:26: sparse: void ( * )( ... ) vim +585 net/netfilter/core.c 2c205dd3981f79c Pablo Neira Ayuso 2018-05-23 578 312a0c16c1fa9dd Patrick McHardy 2013-07-28 579 void nf_ct_attach(struct sk_buff *new, const struct sk_buff *skb) f6ebe77f955d77a Harald Welte 2005-08-09 580 { 312a0c16c1fa9dd Patrick McHardy 2013-07-28 581 void (*attach)(struct sk_buff *, const struct sk_buff *); f6ebe77f955d77a Harald Welte 2005-08-09 582 a9e419dc7be6997 Florian Westphal 2017-01-23 583 if (skb->_nfct) { c3a47ab3e5ad626 Patrick McHardy 2007-02-12 584 rcu_read_lock(); c3a47ab3e5ad626 Patrick McHardy 2007-02-12 @585 attach = rcu_dereference(ip_ct_attach); c3a47ab3e5ad626 Patrick McHardy 2007-02-12 586 if (attach) f6ebe77f955d77a Harald Welte 2005-08-09 587 attach(new, skb); c3a47ab3e5ad626 Patrick McHardy 2007-02-12 588 rcu_read_unlock(); f6ebe77f955d77a Harald Welte 2005-08-09 589 } f6ebe77f955d77a Harald Welte 2005-08-09 590 } f6ebe77f955d77a Harald Welte 2005-08-09 591 EXPORT_SYMBOL(nf_ct_attach); de6e05c49f8b4ed Yasuyuki Kozakai 2007-03-23 592 :::::: The code at line 585 was first introduced by commit :::::: c3a47ab3e5ad62601449e4e5401352271b777e28 [NETFILTER]: Properly use RCU in nf_ct_attach :::::: TO: Patrick McHardy <kaber(a)trash.net&gt; :::::: CC: David S. Miller <davem(a)davemloft.net&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org