Re: [PATCH bpf v1] bpf: Avoid faultable build ID reads under mm locks

[kernel test robot <lkp@intel.com>]

Hi Ihor,

kernel test robot noticed the following build errors:

[auto build test ERROR on bpf/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Ihor-Solodrai/bpf-Avoid-faultable-build-ID-reads-under-mm-locks/20260411-130435
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git master
patch link:    https://lore.kernel.org/r/20260407223003.720428-1-ihor.solodrai%40linux.dev
patch subject: [PATCH bpf v1] bpf: Avoid faultable build ID reads under mm locks
config: i386-buildonly-randconfig-002-20260411 (https://download.01.org/0day-ci/archive/20260411/202604111812.ms5JQMgD-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260411/202604111812.ms5JQMgD-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202604111812.ms5JQMgD-lkp@intel.com/

All errors (new ones prefixed by >>):

>> kernel/bpf/stackmap.c:172:35: error: call to undeclared function 'vma_start_read_locked'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     172 |         if (range_in_vma(vma, ip, ip) && vma_start_read_locked(vma))
         |                                          ^
   kernel/bpf/stackmap.c:172:35: note: did you mean 'vma_assert_write_locked'?
   include/linux/mmap_lock.h:507:20: note: 'vma_assert_write_locked' declared here
     507 | static inline void vma_assert_write_locked(struct vm_area_struct *vma)
         |                    ^
   1 error generated.


vim +/vma_start_read_locked +172 kernel/bpf/stackmap.c

   161	
   162	static struct vm_area_struct *stack_map_lock_vma(struct mm_struct *mm, unsigned long ip)
   163	{
   164		struct vm_area_struct *vma;
   165	
   166		vma = lock_vma_under_rcu(mm, ip);
   167		if (vma)
   168			return vma;
   169	
   170		mmap_read_lock(mm);
   171		vma = find_vma(mm, ip);
 > 172		if (range_in_vma(vma, ip, ip) && vma_start_read_locked(vma))
   173			goto out;
   174	
   175		vma = NULL;
   176	out:
   177		mmap_read_unlock(mm);
   178	
   179		return vma;
   180	}
   181	

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