On Sat, May 15, 2021 at 11:24:25PM +0200, Vlastimil Babka wrote: > > That's a misunderstanding. __kmalloc() is not a dummy function, you > probably found only the header declaration. > Sorry, that was totally my misunderstanding. I was reading dummy function in arch/alpha/boot/bootpz.c:415. I wrongly configured the tool. > It appears clang 10.0.1 is mistakenly evaluating __builtin_constant_p() > as true. Probably something to do with LTO, because MAX_OPTINSN_SIZE > seems it could be a "link-time constant". That is what I was missing. Thank you for kindly explaining it. > Maybe we could extend Marco Elver's followup patch that uses > BUILD_BUG_ON vs BUG() depending on size_is_constant parameter. It could > use BUG() also if the compiler is LLVM < 11 or something. What would be > the proper code for this condition? Fixing clang's bug in linux kernel doesn't seem to be a solution. So now I understand why Nathan said we might require LLVM > 11. I thought I should do something to fix it because I sent the patch. but I was misunderstanding a lot. Thank you sincerely for letting me know. Thanks, Hyeonggon