On Tue, Apr 20, 2021 at 05:18:55PM +0200, David Hildenbrand wrote:

On 20.04.21 17:03, Mike Rapoport wrote:

quoted

On Tue, Apr 20, 2021 at 03:56:28PM +0200, David Hildenbrand wrote:

quoted

On 20.04.21 11:09, Mike Rapoport wrote:

quoted

From: Mike Rapoport <redacted>

The struct pages representing a reserved memory region are initialized
using reserve_bootmem_range() function. This function is called for each
reserved region just before the memory is freed from memblock to the buddy
page allocator.

The struct pages for MEMBLOCK_NOMAP regions are kept with the default
values set by the memory map initialization which makes it necessary to
have a special treatment for such pages in pfn_valid() and
pfn_valid_within().

Just a general question while thinking about it:

Would we right now initialize the memmap of these pages already via
memmap_init_zone()->memmap_init_range()? (IOW, not marking the
PageReserved?)

Yep. These pages are part of memblock.memory so they are initialized in
memmap_init_zone()->memmap_init_range() to the default values.

So instead of fully initializing them again, we mostly would only have to
set PageReserved(). Not sure how big that memory usually is -- IOW, if we
really care about optimizing the double-init.

IIUC, these are small areas reserved by the firmware, like e.g. ACPI
tables.

@Ard, am I right?

-- 
Sincerely yours,
Mike.

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