[PATCH 3/4] mm/hugetlb_vmemmap: remove vmemmap_wrprotect_hvo()
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WARM2d
From: Muchun Song <hidden>
Date: 2026-10-19 09:08:58
Also in:
linux-doc, linux-mm, lkml
Subsystem:
hugetlb subsystem, memory management, memory management - core, the rest · Maintainers:
Muchun Song, Oscar Salvador, Andrew Morton, David Hildenbrand, Linus Torvalds
Shared vmemmap tail pages are now mapped read-only during initial population, so already optimized HugeTLB bootmem folios no longer need a separate write-protection pass. Remove vmemmap_wrprotect_hvo() and skip these folios during boot-time optimization. Signed-off-by: Muchun Song <redacted> --- include/linux/mm.h | 2 -- mm/hugetlb_vmemmap.c | 18 ++++++------------ mm/sparse-vmemmap.c | 23 ----------------------- 3 files changed, 6 insertions(+), 37 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 35f5fc43861a..6f5affe54946 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h@@ -5359,8 +5359,6 @@ int vmemmap_populate_hugepages(unsigned long start, unsigned long end, int node, struct vmem_altmap *altmap); int vmemmap_populate(unsigned long start, unsigned long end, int node, struct vmem_altmap *altmap); -void vmemmap_wrprotect_hvo(unsigned long start, unsigned long end, int node, - unsigned long headsize); void vmemmap_populate_print_last(void); #ifdef CONFIG_MEMORY_HOTPLUG void vmemmap_free(unsigned long start, unsigned long end,
diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c
index 0057fa2a16a8..3d72346c2ca2 100644
--- a/mm/hugetlb_vmemmap.c
+++ b/mm/hugetlb_vmemmap.c@@ -603,19 +603,13 @@ static void __hugetlb_vmemmap_optimize_folios(struct hstate *h, nr_to_optimize = 0; list_for_each_entry(folio, folio_list, lru) { int ret; - unsigned long spfn, epfn; - - if (boot && folio_test_hugetlb_vmemmap_optimized(folio)) { - /* - * Already optimized by pre-HVO, just map the - * mirrored tail page structs RO. - */ - spfn = (unsigned long)&folio->page; - epfn = spfn + hugetlb_vmemmap_size(h); - vmemmap_wrprotect_hvo(spfn, epfn, folio_nid(folio), - HUGETLB_VMEMMAP_RESERVE_SIZE); + + /* + * Bootmem gigantic folios may already be marked optimized when + * their vmemmap layout was prepared earlier, so skip them here. + */ + if (boot && folio_test_hugetlb_vmemmap_optimized(folio)) continue; - } nr_to_optimize++;
diff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c
index ba0496daf4de..0af4b9e791b2 100644
--- a/mm/sparse-vmemmap.c
+++ b/mm/sparse-vmemmap.c@@ -386,29 +386,6 @@ int __meminit vmemmap_populate_basepages(unsigned long start, unsigned long end, return 0; } -/* - * Write protect the mirrored tail page structs for HVO. This will be - * called from the hugetlb code when gathering and initializing the - * memblock allocated gigantic pages. The write protect can't be - * done earlier, since it can't be guaranteed that the reserved - * page structures will not be written to during initialization, - * even if CONFIG_DEFERRED_STRUCT_PAGE_INIT is enabled. - * - * The PTEs are known to exist, and nothing else should be touching - * these pages. The caller is responsible for any TLB flushing. - */ -void vmemmap_wrprotect_hvo(unsigned long addr, unsigned long end, - int node, unsigned long headsize) -{ - unsigned long maddr; - pte_t *pte; - - for (maddr = addr + headsize; maddr < end; maddr += PAGE_SIZE) { - pte = virt_to_kpte(maddr); - ptep_set_wrprotect(&init_mm, maddr, pte); - } -} - void __weak __meminit vmemmap_set_pmd(pmd_t *pmd, void *p, int node, unsigned long addr, unsigned long next) {
--
2.54.0