On 6/6/21 1:08 PM, Hyeonggon Yoo wrote: > On Sat, Jun 05, 2021 at 02:10:46PM +0800, kernel test robot wrote: >> tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master >> head: ccc252d2e818f6a479441119ad453c3ce7c7c461 >> commit: a7ba988ff9de37f0961b4bf96d17aca73d0d2e25 [7012/7430] mm, slub: change run-time assertion in kmalloc_index() to compile-time >> config: parisc-randconfig-r014-20210604 (attached as .config) >> compiler: hppa-linux-gcc (GCC) 9.3.0 >> reproduce (this is a W=1 build): >> wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross >> chmod +x ~/bin/make.cross >> # https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=a7ba988ff9de37f0961b4bf96d17aca73d0d2e25 >> git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git >> git fetch --no-tags linux-next master >> git checkout a7ba988ff9de37f0961b4bf96d17aca73d0d2e25 >> # save the attached .config to linux build tree >> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=parisc >> >> If you fix the issue, kindly add following tag as appropriate >> Reported-by: kernel test robot <lkp@xxxxxxxxx> >> >> All errors (new ones prefixed by >>): >> In file included from <command-line>: >> In function 'kmalloc_index', >> inlined from 'kmalloc_node' at include/linux/slab.h:572:20, >> inlined from 'bpf_map_kmalloc_node.isra.0.part.0' at include/linux/bpf.h:1319:9: >> >> include/linux/compiler_types.h:328:38: error: call to '__compiletime_assert_183' declared with attribute error: unexpected size in kmalloc_index() >> 328 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) >> | ^ >> include/linux/compiler_types.h:309:4: note: in definition of macro '__compiletime_assert' >> 309 | prefix ## suffix(); \ >> | ^~~~~~ >> include/linux/compiler_types.h:328:2: note: in expansion of macro '_compiletime_assert' >> 328 | _compiletime_assert(condition, msg, __compiletime_assert_, __COUNTER__) >> | ^~~~~~~~~~~~~~~~~~~ >> include/linux/build_bug.h:39:37: note: in expansion of macro 'compiletime_assert' >> 39 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) >> | ^~~~~~~~~~~~~~~~~~ >> include/linux/slab.h:389:2: note: in expansion of macro 'BUILD_BUG_ON_MSG' >> 389 | BUILD_BUG_ON_MSG(1, "unexpected size in kmalloc_index()"); >> | ^~~~~~~~~~~~~~~~ > > Reproduce with attached config, and read the code. > It has no problem in clang (clang-10/clang-11). it is problem with gcc. But what exactly is the gcc problem here? Did you have to reproduce it with specific gcc version and/or architecture? > I found two ways to solve the error (maybe there would be better > solution) Any thoughts or opinions? > > > First ways is to change condition of kmalloc_index macro. > > diff --git a/include/linux/slab.h b/include/linux/slab.h > index 70e46db766ca..be2c900cba4b 100644 > --- a/include/linux/slab.h > +++ b/include/linux/slab.h > @@ -397,7 +397,7 @@ static __always_inline unsigned int __kmalloc_index(size_t size, > /* Will never be reached. Needed because the compiler may complain */ > return -1; > } > -#define kmalloc_index(s) __kmalloc_index(s, true) > +#define kmalloc_index(s) __kmalloc_index(s, __builtin_constant_p(s) && true) I wonder how this extra guard can possibly matter? bpf_map_kmalloc_node() kmalloc_node() if (__builtin_constant_p(size) ...) unsigned int i = kmalloc_index(size); We shouldn't be even reaching kmalloc_index() unless __builtin_constant_p(size) is already true. > #endif /* !CONFIG_SLOB */ > > void *__kmalloc(size_t size, gfp_t flags) __assume_kmalloc_alignment __malloc; > > > Second way is making bpf_map_kmalloc_node always inline. If bpf_map_kmalloc_node() is not being compiled as inline, how can it possibly evaluate __builtin_constant_p(size) as true when processing the inlined kmalloc_node()? > diff --git a/include/linux/bpf.h b/include/linux/bpf.h > index 02b02cb29ce2..09379d705349 100644 > --- a/include/linux/bpf.h > +++ b/include/linux/bpf.h > @@ -1312,7 +1312,7 @@ void *bpf_map_kzalloc(const struct bpf_map *map, size_t size, gfp_t flags); > void __percpu *bpf_map_alloc_percpu(const struct bpf_map *map, size_t size, > size_t align, gfp_t flags); > #else > -static inline void * > +static __always_inline void * > bpf_map_kmalloc_node(const struct bpf_map *map, size_t size, gfp_t flags, > int node) > { >
