On Mon, 20 Jun 2022 19:06:14 +0800 Muchun Song <songmuchun@xxxxxxxxxxxxx> wrote: > This series makes hugetlb_optimize_vmemmap compatible with memmap_on_memory > and is based on mm-stable. The reason refers to the patch 2's commit log. > > v5: > - Replace enum to defines per David. > - Walk vmemmap page tables to avoid false-positive. I can't see this second change in the v3->v5 deltas? From: Muchun Song <songmuchun@xxxxxxxxxxxxx> Subject: mm-memory_hotplug-enumerate-all-supported-section-flags-v5 Date: Mon, 20 Jun 2022 19:06:15 +0800 replace enum with defines per David Link: https://lkml.kernel.org/r/20220620110616.12056-2-songmuchun@xxxxxxxxxxxxx Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/mmzone.h | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-) --- a/include/linux/mmzone.h~mm-memory_hotplug-enumerate-all-supported-section-flags-v5 +++ a/include/linux/mmzone.h @@ -1439,16 +1439,13 @@ enum { SECTION_MAP_LAST_BIT, }; -enum { - SECTION_MARKED_PRESENT = BIT(SECTION_MARKED_PRESENT_BIT), - SECTION_HAS_MEM_MAP = BIT(SECTION_HAS_MEM_MAP_BIT), - SECTION_IS_ONLINE = BIT(SECTION_IS_ONLINE_BIT), - SECTION_IS_EARLY = BIT(SECTION_IS_EARLY_BIT), +#define SECTION_MARKED_PRESENT BIT(SECTION_MARKED_PRESENT_BIT) +#define SECTION_HAS_MEM_MAP BIT(SECTION_HAS_MEM_MAP_BIT) +#define SECTION_IS_ONLINE BIT(SECTION_IS_ONLINE_BIT) +#define SECTION_IS_EARLY BIT(SECTION_IS_EARLY_BIT) #ifdef CONFIG_ZONE_DEVICE - SECTION_TAINT_ZONE_DEVICE = BIT(SECTION_TAINT_ZONE_DEVICE_BIT), +#define SECTION_TAINT_ZONE_DEVICE BIT(SECTION_TAINT_ZONE_DEVICE_BIT) #endif -}; - #define SECTION_MAP_MASK (~(BIT(SECTION_MAP_LAST_BIT) - 1)) #define SECTION_NID_SHIFT SECTION_MAP_LAST_BIT _ From: Muchun Song <songmuchun@xxxxxxxxxxxxx> Subject: mm-memory_hotplug-make-hugetlb_optimize_vmemmap-compatible-with-memmap_on_memory-v5 Date: Mon, 20 Jun 2022 19:06:16 +0800 walk vmemmap page tables to avoid false-positive Link: https://lkml.kernel.org/r/20220620110616.12056-3-songmuchun@xxxxxxxxxxxxx Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx> Co-developed-by: Oscar Salvador <osalvador@xxxxxxx> Signed-off-by: Oscar Salvador <osalvador@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/hugetlb_vmemmap.c | 69 ++++++++++++++++++++++++++--------------- 1 file changed, 44 insertions(+), 25 deletions(-) --- a/mm/hugetlb_vmemmap.c~mm-memory_hotplug-make-hugetlb_optimize_vmemmap-compatible-with-memmap_on_memory-v5 +++ a/mm/hugetlb_vmemmap.c @@ -10,6 +10,7 @@ */ #define pr_fmt(fmt) "HugeTLB: " fmt +#include <linux/memory.h> #include "hugetlb_vmemmap.h" /* @@ -99,34 +100,52 @@ int hugetlb_vmemmap_alloc(struct hstate static unsigned int vmemmap_optimizable_pages(struct hstate *h, struct page *head) { - struct mem_section *ms; - struct page *vmemmap_page; - unsigned long pfn = page_to_pfn(head); - if (READ_ONCE(vmemmap_optimize_mode) == VMEMMAP_OPTIMIZE_OFF) return 0; - ms = __pfn_to_section(pfn); - vmemmap_page = sparse_decode_mem_map(ms->section_mem_map, - pfn_to_section_nr(pfn)); - /* - * Only the vmemmap pages' vmemmap may be marked as VmemmapSelfHosted. - * - * Due to HugeTLB alignment requirements, and the vmemmap pages being - * at the start of the hotplugged memory region. Checking any vmemmap - * page's vmemmap is fine. - * - * [ hotplugged memory ] - * [ vmemmap ][ usable memory ] - * ^ | | | - * +---+ | | - * ^ | | - * +--------+ | - * ^ | - * +-----------------+ - */ - if (PageVmemmapSelfHosted(vmemmap_page)) - return 0; + if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG)) { + pmd_t *pmdp, pmd; + struct page *vmemmap_page; + unsigned long vaddr = (unsigned long)head; + + /* + * Only the vmemmap page's vmemmap page can be self-hosted. + * Walking the page tables to find the backing page of the + * vmemmap page. + */ + pmdp = pmd_off_k(vaddr); + /* + * The READ_ONCE() is used to stabilize *pmdp in a register or + * on the stack so that it will stop changing under the code. + * The only concurrent operation where it can be changed is + * split_vmemmap_huge_pmd() (*pmdp will be stable after this + * operation). + */ + pmd = READ_ONCE(*pmdp); + if (pmd_leaf(pmd)) + vmemmap_page = pmd_page(pmd) + pte_index(vaddr); + else + vmemmap_page = pte_page(*pte_offset_kernel(pmdp, vaddr)); + /* + * Due to HugeTLB alignment requirements and the vmemmap pages + * being at the start of the hotplugged memory region in + * memory_hotplug.memmap_on_memory case. Checking any vmemmap + * page's vmemmap page if it is marked as VmemmapSelfHosted is + * sufficient. + * + * [ hotplugged memory ] + * [ section ][...][ section ] + * [ vmemmap ][ usable memory ] + * ^ | | | + * +---+ | | + * ^ | | + * +-------+ | + * ^ | + * +-------------------------------------------+ + */ + if (PageVmemmapSelfHosted(vmemmap_page)) + return 0; + } return hugetlb_optimize_vmemmap_pages(h); } _
