Re: [External] Re: [RFC 2/4] mm/memblock: Add hugepage_size member to struct memblock_region
From: Usama Arif
Date: Thu Jul 27 2023 - 16:57:00 EST
On 27/07/2023 05:30, Mike Rapoport wrote:
On Wed, Jul 26, 2023 at 04:02:21PM +0100, Usama Arif wrote:
On 26/07/2023 12:01, Mike Rapoport wrote:
On Mon, Jul 24, 2023 at 02:46:42PM +0100, Usama Arif wrote:
This propagates the hugepage size from the memblock APIs
(memblock_alloc_try_nid_raw and memblock_alloc_range_nid)
so that it can be stored in struct memblock region. This does not
introduce any functional change and hugepage_size is not used in
this commit. It is just a setup for the next commit where huge_pagesize
is used to skip initialization of struct pages that will be freed later
when HVO is enabled.
Signed-off-by: Usama Arif <usama.arif@xxxxxxxxxxxxx>
---
arch/arm64/mm/kasan_init.c | 2 +-
arch/powerpc/platforms/pasemi/iommu.c | 2 +-
arch/powerpc/platforms/pseries/setup.c | 4 +-
arch/powerpc/sysdev/dart_iommu.c | 2 +-
include/linux/memblock.h | 8 ++-
mm/cma.c | 4 +-
mm/hugetlb.c | 6 +-
mm/memblock.c | 60 ++++++++++++--------
mm/mm_init.c | 2 +-
mm/sparse-vmemmap.c | 2 +-
tools/testing/memblock/tests/alloc_nid_api.c | 2 +-
11 files changed, 56 insertions(+), 38 deletions(-)
[ snip ]
diff --git a/include/linux/memblock.h b/include/linux/memblock.h
index f71ff9f0ec81..bb8019540d73 100644
--- a/include/linux/memblock.h
+++ b/include/linux/memblock.h
@@ -63,6 +63,7 @@ struct memblock_region {
#ifdef CONFIG_NUMA
int nid;
#endif
+ phys_addr_t hugepage_size;
};
/**
@@ -400,7 +401,8 @@ phys_addr_t memblock_phys_alloc_range(phys_addr_t size, phys_addr_t align,
phys_addr_t start, phys_addr_t end);
phys_addr_t memblock_alloc_range_nid(phys_addr_t size,
phys_addr_t align, phys_addr_t start,
- phys_addr_t end, int nid, bool exact_nid);
+ phys_addr_t end, int nid, bool exact_nid,
+ phys_addr_t hugepage_size);
Rather than adding yet another parameter to memblock_phys_alloc_range() we
can have an API that sets a flag on the reserved regions.
With this the hugetlb reservation code can set a flag when HVO is
enabled and memmap_init_reserved_pages() will skip regions with this flag
set.
Hi,
Thanks for the review.
I think you meant memblock_alloc_range_nid/memblock_alloc_try_nid_raw and
not memblock_phys_alloc_range?
Yes.
My initial approach was to use flags, but I think it looks worse than what I
have done in this RFC (I have pushed the flags prototype at
https://github.com/uarif1/linux/commits/flags_skip_prep_init_gigantic_HVO,
top 4 commits for reference (the main difference is patch 2 and 4 from
RFC)). The major points are (the bigger issue is in patch 4):
- (RFC vs flags patch 2 comparison) In the RFC, hugepage_size is propagated
from memblock_alloc_try_nid_raw through function calls. When using flags,
the "no_init" boolean is propogated from memblock_alloc_try_nid_raw through
function calls until the region flags are available in memblock_add_range
and the new MEMBLOCK_NOINIT flag is set. I think its a bit more tricky to
introduce a new function to set the flag in the region AFTER the call to
memblock_alloc_try_nid_raw has finished as the memblock_region can not be
found.
So something (hugepage_size/flag information) still has to be propagated
through function calls and a new argument needs to be added.
Sorry if I wasn't clear. I didn't mean to add flags parameter, I meant to
add a flag and a function that sets this flag for a range. So for
MEMBLOCK_NOINIT there would be
int memblock_mark_noinit(phys_addr_t base, phys_addr_t size);
I'd just name this flag MEMBLOCK_RSRV_NOINIT to make it clear it controls
the reserved regions.
This won't require updating all call sites of memblock_alloc_range_nid()
and memblock_alloc_try_nid_raw() but only a small refactoring of
memblock_setclr_flag() and its callers.
Thanks for this, its much cleaner doing the way you described. I have
sent v1 implementing this
https://lore.kernel.org/all/20230727204624.1942372-1-usama.arif@xxxxxxxxxxxxx/.
Regards,
Usama