On Thu, Jun 13, 2024 at 5:39 PM Ilya Leoshkevich <iii@xxxxxxxxxxxxx> wrote: > > x86's alloc_node_data() rounds up node data size to PAGE_SIZE. It's not > explained why it's needed, but it's most likely for performance > reasons, since the padding bytes are not used anywhere. Some other > architectures do it as well, e.g., mips rounds it up to the cache line > size. > > kmsan_init_shadow() initializes metadata for each node data and assumes > the x86 rounding, which does not match other architectures. This may > cause the range end to overshoot the end of available memory, in turn > causing virt_to_page_or_null() in kmsan_init_alloc_meta_for_range() to > return NULL, which leads to kernel panic shortly after. > > Since the padding bytes are not used, drop the rounding. Nice catch, thanks! > Signed-off-by: Ilya Leoshkevich <iii@xxxxxxxxxxxxx> Reviewed-by: Alexander Potapenko <glider@xxxxxxxxxx>
