| Message ID | 20230825111836.1715308-4-usama.arif@bytedance.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: hugetlb: Skip initialization of gigantic tail struct pages if freed by HVO | expand |
> On Aug 25, 2023, at 19:18, Usama Arif <usama.arif@bytedance.com> wrote: > > 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 > HVO enabled. > > Signed-off-by: Usama Arif <usama.arif@bytedance.com> Reviewed-by: Muchun Song <songmuchun@bytedance.com> One nit below. > --- > include/linux/memblock.h | 10 ++++++++++ > mm/memblock.c | 32 +++++++++++++++++++++++++++----- > 2 files changed, 37 insertions(+), 5 deletions(-) > > diff --git a/include/linux/memblock.h b/include/linux/memblock.h > index f71ff9f0ec81..6d681d053880 100644 > --- a/include/linux/memblock.h > +++ b/include/linux/memblock.h > @@ -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_VMEMMAP: memory region for which struct pages are > + * not initialized (only for reserved regions). We have a more detailed explanation here. > */ > enum memblock_flags { > MEMBLOCK_NONE = 0x0, /* No special request */ > @@ -47,6 +49,8 @@ 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 */ > + /* don't initialize struct pages associated with this reserver memory block */ Those comments right after the macros here seem like a brief explanation. To keep the consistent with others, maybe "don't initialize struct pages" is enough? At least, a detailed one is redundant and repetitive compared with the above one. > + MEMBLOCK_RSRV_NOINIT_VMEMMAP = 0x10, > };
On Fri, Aug 25, 2023 at 12:18:35PM +0100, Usama Arif wrote: > 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 > HVO enabled. > > Signed-off-by: Usama Arif <usama.arif@bytedance.com> > --- > include/linux/memblock.h | 10 ++++++++++ > mm/memblock.c | 32 +++++++++++++++++++++++++++----- > 2 files changed, 37 insertions(+), 5 deletions(-) > > diff --git a/include/linux/memblock.h b/include/linux/memblock.h > index f71ff9f0ec81..6d681d053880 100644 > --- a/include/linux/memblock.h > +++ b/include/linux/memblock.h > @@ -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_VMEMMAP: memory region for which struct pages are > + * not initialized (only for reserved regions). > */ > enum memblock_flags { > MEMBLOCK_NONE = 0x0, /* No special request */ > @@ -47,6 +49,8 @@ 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 */ > + /* don't initialize struct pages associated with this reserver memory block */ > + MEMBLOCK_RSRV_NOINIT_VMEMMAP = 0x10, The flag means that struct page shouldn't be initialized, it may be used not only by vmemmap optimizations. Please drop _VMEMMAP. And I agree with Muchun's remarks about the comments. > }; > > /** > @@ -125,6 +129,7 @@ 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_vmemmap(phys_addr_t base, phys_addr_t size); memblock does not care about vmemmap, please drop _vmemmap here and below as well. > void memblock_free_all(void); > void memblock_free(void *ptr, size_t size); > @@ -259,6 +264,11 @@ static inline bool memblock_is_nomap(struct memblock_region *m) > return m->flags & MEMBLOCK_NOMAP; > } > > +static inline bool memblock_is_noinit_vmemmap(struct memblock_region *m) memblock_is_reserved_noinit please. > +{ > + return m->flags & MEMBLOCK_RSRV_NOINIT_VMEMMAP; > +} > + > static inline bool memblock_is_driver_managed(struct memblock_region *m) > { > return m->flags & MEMBLOCK_DRIVER_MANAGED; > diff --git a/mm/memblock.c b/mm/memblock.c > index 43cb4404d94c..a9782228c840 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -991,6 +991,23 @@ 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_vmemmap - Mark a reserved memory region with flag > + * MEMBLOCK_RSRV_NOINIT_VMEMMAP. this should be about what marking RSRV_NOINIT does, not what flag it uses > + * @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_VMEMMAP. > + * > + * Return: 0 on success, -errno on failure. > + */ > +int __init_memblock memblock_reserved_mark_noinit_vmemmap(phys_addr_t base, phys_addr_t size) > +{ > + return memblock_setclr_flag(&memblock.reserved, base, size, 1, > + MEMBLOCK_RSRV_NOINIT_VMEMMAP); > +} > + > static bool should_skip_region(struct memblock_type *type, > struct memblock_region *m, > int nid, int flags) > @@ -2107,13 +2124,18 @@ 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_VMEMMAP flag set > + */ > for_each_reserved_mem_region(region) { > - nid = memblock_get_region_node(region); > - start = region->base; > - end = start + region->size; > + if (!memblock_is_noinit_vmemmap(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); > + } > } > } > > -- > 2.25.1 >
On 2023/8/28 15:47, Mike Rapoport wrote: > On Fri, Aug 25, 2023 at 12:18:35PM +0100, Usama Arif wrote: >> 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 >> HVO enabled. >> >> Signed-off-by: Usama Arif <usama.arif@bytedance.com> >> --- >> include/linux/memblock.h | 10 ++++++++++ >> mm/memblock.c | 32 +++++++++++++++++++++++++++----- >> 2 files changed, 37 insertions(+), 5 deletions(-) >> >> diff --git a/include/linux/memblock.h b/include/linux/memblock.h >> index f71ff9f0ec81..6d681d053880 100644 >> --- a/include/linux/memblock.h >> +++ b/include/linux/memblock.h >> @@ -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_VMEMMAP: memory region for which struct pages are >> + * not initialized (only for reserved regions). >> */ >> enum memblock_flags { >> MEMBLOCK_NONE = 0x0, /* No special request */ >> @@ -47,6 +49,8 @@ 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 */ >> + /* don't initialize struct pages associated with this reserver memory block */ >> + MEMBLOCK_RSRV_NOINIT_VMEMMAP = 0x10, > The flag means that struct page shouldn't be initialized, it may be used > not only by vmemmap optimizations. > Please drop _VMEMMAP. The area at where the struct pages located is vmemmap, I think the "vmemap" suffix does not mean that it is for "vmemmap optimization", it could specify the target which will not be initialized. For me, MEMBLOCK_RSRV_NOINIT does not tell me what should not be initialized, memblock itself or its struct page (aka vmemmap pages)? So maybe the suffix is better to keep? > > And I agree with Muchun's remarks about the comments. > > > >> }; >> >> /** >> @@ -125,6 +129,7 @@ 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_vmemmap(phys_addr_t base, phys_addr_t size); > memblock does not care about vmemmap, please drop _vmemmap here and below as well. > >> void memblock_free_all(void); >> void memblock_free(void *ptr, size_t size); >> @@ -259,6 +264,11 @@ static inline bool memblock_is_nomap(struct memblock_region *m) >> return m->flags & MEMBLOCK_NOMAP; >> } >> >> +static inline bool memblock_is_noinit_vmemmap(struct memblock_region *m) > memblock_is_reserved_noinit please. > >> +{ >> + return m->flags & MEMBLOCK_RSRV_NOINIT_VMEMMAP; >> +} >> + >> static inline bool memblock_is_driver_managed(struct memblock_region *m) >> { >> return m->flags & MEMBLOCK_DRIVER_MANAGED; >> diff --git a/mm/memblock.c b/mm/memblock.c >> index 43cb4404d94c..a9782228c840 100644 >> --- a/mm/memblock.c >> +++ b/mm/memblock.c >> @@ -991,6 +991,23 @@ 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_vmemmap - Mark a reserved memory region with flag >> + * MEMBLOCK_RSRV_NOINIT_VMEMMAP. > this should be about what marking RSRV_NOINIT does, not what flag it uses > >> + * @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_VMEMMAP. >> + * >> + * Return: 0 on success, -errno on failure. >> + */ >> +int __init_memblock memblock_reserved_mark_noinit_vmemmap(phys_addr_t base, phys_addr_t size) >> +{ >> + return memblock_setclr_flag(&memblock.reserved, base, size, 1, >> + MEMBLOCK_RSRV_NOINIT_VMEMMAP); >> +} >> + >> static bool should_skip_region(struct memblock_type *type, >> struct memblock_region *m, >> int nid, int flags) >> @@ -2107,13 +2124,18 @@ 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_VMEMMAP flag set >> + */ >> for_each_reserved_mem_region(region) { >> - nid = memblock_get_region_node(region); >> - start = region->base; >> - end = start + region->size; >> + if (!memblock_is_noinit_vmemmap(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); >> + } >> } >> } >> >> -- >> 2.25.1 >>
On Mon, Aug 28, 2023 at 04:52:10PM +0800, Muchun Song wrote: > > > On 2023/8/28 15:47, Mike Rapoport wrote: > > On Fri, Aug 25, 2023 at 12:18:35PM +0100, Usama Arif wrote: > > > 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 > > > HVO enabled. > > > > > > Signed-off-by: Usama Arif <usama.arif@bytedance.com> > > > --- > > > include/linux/memblock.h | 10 ++++++++++ > > > mm/memblock.c | 32 +++++++++++++++++++++++++++----- > > > 2 files changed, 37 insertions(+), 5 deletions(-) > > > > > > diff --git a/include/linux/memblock.h b/include/linux/memblock.h > > > index f71ff9f0ec81..6d681d053880 100644 > > > --- a/include/linux/memblock.h > > > +++ b/include/linux/memblock.h > > > @@ -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_VMEMMAP: memory region for which struct pages are > > > + * not initialized (only for reserved regions). > > > */ > > > enum memblock_flags { > > > MEMBLOCK_NONE = 0x0, /* No special request */ > > > @@ -47,6 +49,8 @@ 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 */ > > > + /* don't initialize struct pages associated with this reserver memory block */ > > > + MEMBLOCK_RSRV_NOINIT_VMEMMAP = 0x10, > > The flag means that struct page shouldn't be initialized, it may be used > > not only by vmemmap optimizations. > > Please drop _VMEMMAP. > > The area at where the struct pages located is vmemmap, I think the > "vmemap" suffix does not mean that it is for "vmemmap optimization", > it could specify the target which will not be initialized. For me, > MEMBLOCK_RSRV_NOINIT does not tell me what should not be initialized, > memblock itself or its struct page (aka vmemmap pages)? So maybe > the suffix is better to keep? In general case the area is memmap rather than vmemmap, so a better suffix then would be _MEMMAP. I'm not too fond of that either, but I cannot think of better name. > > > > And I agree with Muchun's remarks about the comments. > > > > > > > > > }; > > > /** > > > @@ -125,6 +129,7 @@ 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_vmemmap(phys_addr_t base, phys_addr_t size); > > memblock does not care about vmemmap, please drop _vmemmap here and below as well. > > > void memblock_free_all(void); > > > void memblock_free(void *ptr, size_t size); > > > @@ -259,6 +264,11 @@ static inline bool memblock_is_nomap(struct memblock_region *m) > > > return m->flags & MEMBLOCK_NOMAP; > > > } > > > +static inline bool memblock_is_noinit_vmemmap(struct memblock_region *m) > > memblock_is_reserved_noinit please. > > > > > +{ > > > + return m->flags & MEMBLOCK_RSRV_NOINIT_VMEMMAP; > > > +} > > > + > > > static inline bool memblock_is_driver_managed(struct memblock_region *m) > > > { > > > return m->flags & MEMBLOCK_DRIVER_MANAGED; > > > diff --git a/mm/memblock.c b/mm/memblock.c > > > index 43cb4404d94c..a9782228c840 100644 > > > --- a/mm/memblock.c > > > +++ b/mm/memblock.c > > > @@ -991,6 +991,23 @@ 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_vmemmap - Mark a reserved memory region with flag > > > + * MEMBLOCK_RSRV_NOINIT_VMEMMAP. > > this should be about what marking RSRV_NOINIT does, not what flag it uses > > > > > + * @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_VMEMMAP. > > > + * > > > + * Return: 0 on success, -errno on failure. > > > + */ > > > +int __init_memblock memblock_reserved_mark_noinit_vmemmap(phys_addr_t base, phys_addr_t size) > > > +{ > > > + return memblock_setclr_flag(&memblock.reserved, base, size, 1, > > > + MEMBLOCK_RSRV_NOINIT_VMEMMAP); > > > +} > > > + > > > static bool should_skip_region(struct memblock_type *type, > > > struct memblock_region *m, > > > int nid, int flags) > > > @@ -2107,13 +2124,18 @@ 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_VMEMMAP flag set > > > + */ > > > for_each_reserved_mem_region(region) { > > > - nid = memblock_get_region_node(region); > > > - start = region->base; > > > - end = start + region->size; > > > + if (!memblock_is_noinit_vmemmap(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); > > > + } > > > } > > > } > > > -- > > > 2.25.1 > > > >
> On Aug 28, 2023, at 17:09, Mike Rapoport <rppt@kernel.org> wrote: > > On Mon, Aug 28, 2023 at 04:52:10PM +0800, Muchun Song wrote: >> >> >> On 2023/8/28 15:47, Mike Rapoport wrote: >>> On Fri, Aug 25, 2023 at 12:18:35PM +0100, Usama Arif wrote: >>>> 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 >>>> HVO enabled. >>>> >>>> Signed-off-by: Usama Arif <usama.arif@bytedance.com> >>>> --- >>>> include/linux/memblock.h | 10 ++++++++++ >>>> mm/memblock.c | 32 +++++++++++++++++++++++++++----- >>>> 2 files changed, 37 insertions(+), 5 deletions(-) >>>> >>>> diff --git a/include/linux/memblock.h b/include/linux/memblock.h >>>> index f71ff9f0ec81..6d681d053880 100644 >>>> --- a/include/linux/memblock.h >>>> +++ b/include/linux/memblock.h >>>> @@ -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_VMEMMAP: memory region for which struct pages are >>>> + * not initialized (only for reserved regions). >>>> */ >>>> enum memblock_flags { >>>> MEMBLOCK_NONE = 0x0, /* No special request */ >>>> @@ -47,6 +49,8 @@ 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 */ >>>> + /* don't initialize struct pages associated with this reserver memory block */ >>>> + MEMBLOCK_RSRV_NOINIT_VMEMMAP = 0x10, >>> The flag means that struct page shouldn't be initialized, it may be used >>> not only by vmemmap optimizations. >>> Please drop _VMEMMAP. >> >> The area at where the struct pages located is vmemmap, I think the >> "vmemap" suffix does not mean that it is for "vmemmap optimization", >> it could specify the target which will not be initialized. For me, >> MEMBLOCK_RSRV_NOINIT does not tell me what should not be initialized, >> memblock itself or its struct page (aka vmemmap pages)? So maybe >> the suffix is better to keep? > In general case the area is memmap rather than vmemmap, so a better suffix Right. memmap > then would be _MEMMAP. I'm not too fond of that either, but I cannot think > of better name. I have no strong opinion, if we cannot think a better name, just drop the suffix as you suggested and let the comments more specified. :-) Thanks.
diff --git a/include/linux/memblock.h b/include/linux/memblock.h index f71ff9f0ec81..6d681d053880 100644 --- a/include/linux/memblock.h +++ b/include/linux/memblock.h @@ -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_VMEMMAP: memory region for which struct pages are + * not initialized (only for reserved regions). */ enum memblock_flags { MEMBLOCK_NONE = 0x0, /* No special request */ @@ -47,6 +49,8 @@ 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 */ + /* don't initialize struct pages associated with this reserver memory block */ + MEMBLOCK_RSRV_NOINIT_VMEMMAP = 0x10, }; /** @@ -125,6 +129,7 @@ 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_vmemmap(phys_addr_t base, phys_addr_t size); void memblock_free_all(void); void memblock_free(void *ptr, size_t size); @@ -259,6 +264,11 @@ static inline bool memblock_is_nomap(struct memblock_region *m) return m->flags & MEMBLOCK_NOMAP; } +static inline bool memblock_is_noinit_vmemmap(struct memblock_region *m) +{ + return m->flags & MEMBLOCK_RSRV_NOINIT_VMEMMAP; +} + static inline bool memblock_is_driver_managed(struct memblock_region *m) { return m->flags & MEMBLOCK_DRIVER_MANAGED; diff --git a/mm/memblock.c b/mm/memblock.c index 43cb4404d94c..a9782228c840 100644 --- a/mm/memblock.c +++ b/mm/memblock.c @@ -991,6 +991,23 @@ 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_vmemmap - Mark a reserved memory region with flag + * MEMBLOCK_RSRV_NOINIT_VMEMMAP. + * @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_VMEMMAP. + * + * Return: 0 on success, -errno on failure. + */ +int __init_memblock memblock_reserved_mark_noinit_vmemmap(phys_addr_t base, phys_addr_t size) +{ + return memblock_setclr_flag(&memblock.reserved, base, size, 1, + MEMBLOCK_RSRV_NOINIT_VMEMMAP); +} + static bool should_skip_region(struct memblock_type *type, struct memblock_region *m, int nid, int flags) @@ -2107,13 +2124,18 @@ 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_VMEMMAP flag set + */ for_each_reserved_mem_region(region) { - nid = memblock_get_region_node(region); - start = region->base; - end = start + region->size; + if (!memblock_is_noinit_vmemmap(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); + } } }
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 HVO enabled. Signed-off-by: Usama Arif <usama.arif@bytedance.com> --- include/linux/memblock.h | 10 ++++++++++ mm/memblock.c | 32 +++++++++++++++++++++++++++----- 2 files changed, 37 insertions(+), 5 deletions(-)