On Fri, Jun 13, 2025, avinashlalotra wrote: > Building the kernel with LLVM fails due to > a stack frame size overflow in `kvm_hv_flush_tlb()`: > > arch/x86/kvm/hyperv.c:2001:12: error: stack frame size (1336) exceeds limit (1024) in 'kvm_hv_flush_tlb' [-Werror,-Wframe-larger-than] > > The issue is caused by a large bitmap allocated on the stack. To resolve > this, dynamically allocate the bitmap using `bitmap_zalloc()` and free it with > `bitmap_free()` after use. This reduces the function's stack usage and avoids > the compiler error when `-Werror` is set. Can you provide your full .config? It's not at all difficult to get this function (and others) to exceed the frame size with various sanitizers and/or deubg options enabled, which is why KVM_WERROR depends on EXPERT=y or KASAN=n. config KVM_WERROR bool "Compile KVM with -Werror" # Disallow KVM's -Werror if KASAN is enabled, e.g. to guard against # randomized configs from selecting KVM_WERROR=y, which doesn't play # nice with KASAN. KASAN builds generates warnings for the default # FRAME_WARN, i.e. KVM_WERROR=y with KASAN=y requires special tuning. # Building KVM with -Werror and KASAN is still doable via enabling # the kernel-wide WERROR=y. depends on KVM && ((EXPERT && !KASAN) || WERROR) And also why kernel/configs/debug.config bumps the size to 2048. CONFIG_FRAME_WARN=2048 > Please provide me feedback about this patch . There were more warnings like > that, So If this is the correct way to fic such issues then I will submit > patches for them. As above, this may just be a "bad" .config.
