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.
