Hi Mike,
On 01/08/19 at 10:05am, Mike Rapoport wrote:
> I'm not thrilled by duplicating this code (yet again).
> I liked the v3 of this patch [1] more, assuming we allow bottom-up mode to
> allocate [0, kernel_start) unconditionally.
> I'd just replace you first patch in v3 [2] with something like:
In initmem_init(), we will restore the top-down allocation style anyway.
While reserve_crashkernel() is called after initmem_init(), it's not
appropriate to adjust memblock_find_in_range_node(), and we really want
to find region bottom up for crashkernel reservation, no matter where
kernel is loaded, better call __memblock_find_range_bottom_up().
Create a wrapper to do the necessary handling, then call
__memblock_find_range_bottom_up() directly, looks better.
Thanks
Baoquan
>
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 7df468c..d1b30b9 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -274,24 +274,14 @@ phys_addr_t __init_memblock
> memblock_find_in_range_node(phys_addr_t size,
> * try bottom-up allocation only when bottom-up mode
> * is set and @end is above the kernel image.
> */
> - if (memblock_bottom_up() && end > kernel_end) {
> - phys_addr_t bottom_up_start;
> -
> - /* make sure we will allocate above the kernel */
> - bottom_up_start = max(start, kernel_end);
> -
> + if (memblock_bottom_up()) {
> /* ok, try bottom-up allocation first */
> - ret = __memblock_find_range_bottom_up(bottom_up_start, end,
> + ret = __memblock_find_range_bottom_up(start, end,
> size, align, nid, flags);
> if (ret)
> return ret;
>
> /*
> - * we always limit bottom-up allocation above the kernel,
> - * but top-down allocation doesn't have the limit, so
> - * retrying top-down allocation may succeed when bottom-up
> - * allocation failed.
> - *
> * bottom-up allocation is expected to be fail very rarely,
> * so we use WARN_ONCE() here to see the stack trace if
> * fail happens.
>
> [1]
> https://lore.kernel.org/lkml/1545966002-3075-3-git-send-email-kernelf...@gmail.com/
> [2]
> https://lore.kernel.org/lkml/1545966002-3075-2-git-send-email-kernelf...@gmail.com/
>
> > +
> > + return ret;
> > +}
> > +
> > /**
> > * __memblock_find_range_top_down - find free area utility, in top-down
> > * @start: start of candidate range
> > --
> > 2.7.4
> >
>
> --
> Sincerely yours,
> Mike.
>
