On Tue, Apr 16, 2024 at 06:00:29PM +0100, Matthew Wilcox wrote: > On Tue, Apr 16, 2024 at 07:31:54PM +0300, Mike Rapoport wrote: > > > @@ -238,17 +237,9 @@ static void __init setup_bootmem(void) > > > /* > > > * memblock allocator is not aware of the fact that last 4K bytes of > > > * the addressable memory can not be mapped because of IS_ERR_VALUE > > > - * macro. Make sure that last 4k bytes are not usable by memblock > > > - * if end of dram is equal to maximum addressable memory. For 64-bit > > > - * kernel, this problem can't happen here as the end of the virtual > > > - * address space is occupied by the kernel mapping then this check must > > > - * be done as soon as the kernel mapping base address is determined. > > > + * macro. Make sure that last 4k bytes are not usable by memblock. > > > */ > > > > It's not only memblock, but buddy as well, so maybe > > > > /* > > * The last 4K bytes of the addressable memory can not be used > > * because of IS_ERR_VALUE macro. Make sure that last 4K bytes are > > * not usable by kernel memory allocators. > > */ > > > > > - if (!IS_ENABLED(CONFIG_64BIT)) { > > > - max_mapped_addr = __pa(~(ulong)0); > > > - if (max_mapped_addr == (phys_ram_end - 1)) > > > - memblock_set_current_limit(max_mapped_addr - 4096); > > > - } > > > + memblock_reserve(__pa(-PAGE_SIZE), PAGE_SIZE); > > > > Ack. > > Can this go to generic code instead of letting architecture maintainers > fall over it? Yes, it's just have to happen before setup_arch() where most architectures enable memblock allocations. -- Sincerely yours, Mike.