Messages in this thread | | | Subject | Re: [PATCH 1/3] mm,memory_hotplug: export mhp min alignment | From | Max Gurtovoy <> | Date | Mon, 21 Jun 2021 19:11:12 +0300 |
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hi David,
do we have a conclusion for this series ?
Is the below suggestion accepted by the maintainers ?
I would like to send a new series before closing 5.14 merge window.
On 6/3/2021 1:52 PM, Max Gurtovoy wrote: > > On 6/2/2021 3:14 PM, David Hildenbrand wrote: >> On 02.06.21 13:10, Max Gurtovoy wrote: >>> Hotplugged memory has alignmet restrictions. E.g, it disallows all >>> operations smaller than a sub-section and only allow operations smaller >>> than a section for SPARSEMEM_VMEMMAP. Export the alignment restrictions >>> for mhp users. >>> >>> Signed-off-by: Max Gurtovoy <mgurtovoy@nvidia.com> >>> --- >>> include/linux/memory_hotplug.h | 5 +++++ >>> mm/memory_hotplug.c | 33 +++++++++++++++++++-------------- >>> 2 files changed, 24 insertions(+), 14 deletions(-) >>> >>> diff --git a/include/linux/memory_hotplug.h >>> b/include/linux/memory_hotplug.h >>> index 28f32fd00fe9..c55a9049b11e 100644 >>> --- a/include/linux/memory_hotplug.h >>> +++ b/include/linux/memory_hotplug.h >>> @@ -76,6 +76,7 @@ struct mhp_params { >>> bool mhp_range_allowed(u64 start, u64 size, bool need_mapping); >>> struct range mhp_get_pluggable_range(bool need_mapping); >>> +unsigned long mhp_get_min_align(void); >>> /* >>> * Zone resizing functions >>> @@ -248,6 +249,10 @@ void mem_hotplug_done(void); >>> ___page; \ >>> }) >>> +static inline unsigned long mhp_get_min_align(void) >>> +{ >>> + return 0; >>> +} >>> static inline unsigned zone_span_seqbegin(struct zone *zone) >>> { >>> return 0; >>> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c >>> index 9e86e9ee0a10..161bb6704a9b 100644 >>> --- a/mm/memory_hotplug.c >>> +++ b/mm/memory_hotplug.c >>> @@ -270,24 +270,29 @@ void __init >>> register_page_bootmem_info_node(struct pglist_data *pgdat) >>> } >>> #endif /* CONFIG_HAVE_BOOTMEM_INFO_NODE */ >>> +/* >>> + * Disallow all operations smaller than a sub-section and only >>> + * allow operations smaller than a section for >>> + * SPARSEMEM_VMEMMAP. Note that check_hotplug_memory_range() >>> + * enforces a larger memory_block_size_bytes() granularity for >>> + * memory that will be marked online, so this check should only >>> + * fire for direct arch_{add,remove}_memory() users outside of >>> + * add_memory_resource(). >>> + */ >>> +unsigned long mhp_get_min_align(void) >>> +{ >>> + if (IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP)) >>> + return PAGES_PER_SUBSECTION; >>> + return PAGES_PER_SECTION; >>> +} >>> +EXPORT_SYMBOL_GPL(mhp_get_min_align); >> >> We have to main interfaces to "hotplug" memory: >> >> a) add_memory() and friends for System RAM, which have memory block >> alignment requirements. >> >> b) memremap_pages(), which has the alignemnt requirements you mention >> here. >> >> I feel like what you need would better be exposed in mm/memremap.c, >> for example, via "memremap_min_alignment" so it matches the >> "memremap_pages" semantics. >> >> And then, memremap_pages() is only available with CONFIG_ZONE_DEVICE, >> which depends on SPARSEMEM_VMEMMAP. So you'll always have >> PAGES_PER_SUBSECTION. >> >> I can already spot "memremap_compat_align", maybe you can reuse that >> or handle it accordingly in there? > > Yes I think that since subsection is aligned to PAGE_SIZE I can do: > > size_t pci_p2pdma_align_size(size_t size) > { > unsigned long min_align; > > min_align = memremap_compat_align(); > if (!IS_ALIGNED(size, min_align)) > return ALIGN_DOWN(size, min_align); > > return size; > } > > > thoughts ? > >> > > _______________________________________________ > Linux-nvme mailing list > Linux-nvme@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-nvme
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