Sean Christopherson <[email protected]> writes: > On Tue, Feb 17, 2026, Ackerley Tng wrote: >> >> [...snip...] >> >> + >> + /* >> + * Use aligned address so that MADV_COLLAPSE will not be >> + * filtered out early in the collapsing routine. > > Please elaborate, the value below is way more magical than just being aligned. > >> + */ >> +#define ALIGNED_ADDRESS ((void *)0x4000000000UL) > > Use a "const void *" instead of #define inside a function. And use one of the > appropriate size macros, e.g. > > const void *ALIGNED_ADDRESS = (void *)(SZ_1G * <some magic value>); > > But why hardcode a virtual address in the first place? If you a specific > alignment, just allocate enough virtual memory to be able to meet those > alignment > requirements. > >> + mem = mmap(ALIGNED_ADDRESS, pmd_size, PROT_READ | PROT_WRITE, >> + MAP_FIXED | MAP_SHARED, fd, 0); >> >> [...snip...] >> >> @@ -370,6 +441,7 @@ static void __test_guest_memfd(struct kvm_vm *vm, >> uint64_t flags) >> gmem_test(mmap_supported, vm, flags); >> gmem_test(fault_overflow, vm, flags); >> gmem_test(numa_allocation, vm, flags); >> + test_collapse(vm, flags); > > Why diverge from everything else? Yeah, the size is different, but that's > easy > enough to handle. And presumably the THP query needs to be able to fail > gracefully, > so something like this? > > > [...snip...] >
Addressed your comments in a v2 [*], thanks for reviewing! [*] https://lore.kernel.org/all/[email protected]/T/
