From 9eb6207b7812cee13431831c9661d21b53f3e93f Mon Sep 17 00:00:00 2001 From: Frank van der Linden Date: Fri, 28 Feb 2025 18:29:15 +0000 Subject: mm/sparse: add vmemmap_*_hvo functions Add a few functions to enable early HVO: vmemmap_populate_hvo vmemmap_undo_hvo vmemmap_wrprotect_hvo The populate and undo functions are expected to be used in early init, from the sparse_init_nid_early() function. The wrprotect function is to be used, potentially, later. To implement these functions, mostly re-use the existing compound pages vmemmap logic used by DAX. vmemmap_populate_address has its argument changed a bit in this commit: the page structure passed in to be reused in the mapping is replaced by a PFN and a flag. The flag indicates whether an extra ref should be taken on the vmemmap page containing the head page structure. Taking the ref is appropriate to for DAX / ZONE_DEVICE, but not for HugeTLB HVO. The HugeTLB vmemmap optimization maps tail page structure pages read-only. The vmemmap_wrprotect_hvo function that does this is implemented separately, because it cannot be guaranteed that reserved page structures will not be write accessed during memory initialization. Even with CONFIG_DEFERRED_STRUCT_PAGE_INIT, they might still be written to (if they are at the bottom of a zone). So, vmemmap_populate_hvo leaves the tail page structure pages RW initially, and then later during initialization, after memmap init is fully done, vmemmap_wrprotect_hvo must be called to finish the job. Subsequent commits will use these functions for early HugeTLB HVO. Link: https://lkml.kernel.org/r/20250228182928.2645936-15-fvdl@google.com Signed-off-by: Frank van der Linden Cc: Alexander Gordeev Cc: Andy Lutomirski Cc: Arnd Bergmann Cc: Dan Carpenter Cc: Dave Hansen Cc: David Hildenbrand Cc: Heiko Carstens Cc: Joao Martins Cc: Johannes Weiner Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Muchun Song Cc: Oscar Salvador Cc: Peter Zijlstra Cc: Roman Gushchin (Cruise) Cc: Usama Arif Cc: Vasily Gorbik Cc: Yu Zhao Cc: Zi Yan Signed-off-by: Andrew Morton --- include/linux/mm.h | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) (limited to 'include/linux') diff --git a/include/linux/mm.h b/include/linux/mm.h index 03e4807bd911..9a74a3ee68bc 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -3937,7 +3937,8 @@ p4d_t *vmemmap_p4d_populate(pgd_t *pgd, unsigned long addr, int node); pud_t *vmemmap_pud_populate(p4d_t *p4d, unsigned long addr, int node); pmd_t *vmemmap_pmd_populate(pud_t *pud, unsigned long addr, int node); pte_t *vmemmap_pte_populate(pmd_t *pmd, unsigned long addr, int node, - struct vmem_altmap *altmap, struct page *reuse); + struct vmem_altmap *altmap, unsigned long ptpfn, + unsigned long flags); void *vmemmap_alloc_block(unsigned long size, int node); struct vmem_altmap; void *vmemmap_alloc_block_buf(unsigned long size, int node, @@ -3953,6 +3954,12 @@ 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); +int vmemmap_populate_hvo(unsigned long start, unsigned long end, int node, + unsigned long headsize); +int vmemmap_undo_hvo(unsigned long start, unsigned long end, int node, + unsigned long headsize); +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, -- cgit v1.2.3