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memblock: introduce MEMBLOCK_RSRV_NOINIT flag 

For reserved memory regions marked with this flag, reserve_bootmem_region
is not called during memmap_init_reserved_pages.  This can be used to
avoid struct page initialization for regions which won't need them, for
e.g.  hugepages with Hugepage Vmemmap Optimization enabled.

Link: https://lkml.kernel.org/r/20230913105401.519709-4-usama.arif@bytedance.com
Signed-off-by: Usama Arif <usama.arif@bytedance.com>
Acked-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Fam Zheng <fam.zheng@bytedance.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Punit Agrawal <punit.agrawal@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Usama Arif 2023-09-13 11:54:00 +01:00 committed by Andrew Morton
parent ee8d2071ef
commit 77e6c43e13
2 changed files with 37 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
include/linux/memblock.h
View File

@ -40,6 +40,8 @@ extern unsigned long long max_possible_pfn;
* via a driver, and never indicated in the firmware-provided memory map as
* system RAM. This corresponds to IORESOURCE_SYSRAM_DRIVER_MANAGED in the
* kernel resource tree.
* @MEMBLOCK_RSRV_NOINIT: memory region for which struct pages are
* not initialized (only for reserved regions).
*/
enum memblock_flags {
MEMBLOCK_NONE = 0x0, /* No special request */
@ -47,6 +49,7 @@ enum memblock_flags {
MEMBLOCK_MIRROR = 0x2, /* mirrored region */
MEMBLOCK_NOMAP = 0x4, /* don't add to kernel direct mapping */
MEMBLOCK_DRIVER_MANAGED = 0x8, /* always detected via a driver */
MEMBLOCK_RSRV_NOINIT = 0x10, /* don't initialize struct pages */
};
/**
@ -125,6 +128,7 @@ int memblock_clear_hotplug(phys_addr_t base, phys_addr_t size);
int memblock_mark_mirror(phys_addr_t base, phys_addr_t size);
int memblock_mark_nomap(phys_addr_t base, phys_addr_t size);
int memblock_clear_nomap(phys_addr_t base, phys_addr_t size);
int memblock_reserved_mark_noinit(phys_addr_t base, phys_addr_t size);
void memblock_free_all(void);
void memblock_free(void *ptr, size_t size);
@ -259,6 +263,11 @@ static inline bool memblock_is_nomap(struct memblock_region *m)
return m->flags & MEMBLOCK_NOMAP;
}
static inline bool memblock_is_reserved_noinit(struct memblock_region *m)
{
return m->flags & MEMBLOCK_RSRV_NOINIT;
}
static inline bool memblock_is_driver_managed(struct memblock_region *m)
{
return m->flags & MEMBLOCK_DRIVER_MANAGED;

33
mm/memblock.c
View File

@ -997,6 +997,24 @@ int __init_memblock memblock_clear_nomap(phys_addr_t base, phys_addr_t size)
return memblock_setclr_flag(&memblock.memory, base, size, 0, MEMBLOCK_NOMAP);
}
/**
* memblock_reserved_mark_noinit - Mark a reserved memory region with flag
* MEMBLOCK_RSRV_NOINIT which results in the struct pages not being initialized
* for this region.
* @base: the base phys addr of the region
* @size: the size of the region
*
* struct pages will not be initialized for reserved memory regions marked with
* %MEMBLOCK_RSRV_NOINIT.
*
* Return: 0 on success, -errno on failure.
*/
int __init_memblock memblock_reserved_mark_noinit(phys_addr_t base, phys_addr_t size)
{
return memblock_setclr_flag(&memblock.reserved, base, size, 1,
MEMBLOCK_RSRV_NOINIT);
}
static bool should_skip_region(struct memblock_type *type,
struct memblock_region *m,
int nid, int flags)
@ -2113,13 +2131,18 @@ static void __init memmap_init_reserved_pages(void)
memblock_set_node(start, end, &memblock.reserved, nid);
}
/* initialize struct pages for the reserved regions */
/*
* initialize struct pages for reserved regions that don't have
* the MEMBLOCK_RSRV_NOINIT flag set
*/
for_each_reserved_mem_region(region) {
nid = memblock_get_region_node(region);
start = region->base;
end = start + region->size;
if (!memblock_is_reserved_noinit(region)) {
nid = memblock_get_region_node(region);
start = region->base;
end = start + region->size;
reserve_bootmem_region(start, end, nid);
reserve_bootmem_region(start, end, nid);
}
}
}