linux-kernel - [PATCH v3 10/11] mm/vmalloc: Enter lazy mmu mode while manipulating vmalloc ptes

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Message-ID: <20250304150444.3788920-11-ryan.roberts@arm.com>
Date: Tue,  4 Mar 2025 15:04:40 +0000
From: Ryan Roberts <ryan.roberts@....com>
To: Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	Pasha Tatashin <pasha.tatashin@...een.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Uladzislau Rezki <urezki@...il.com>,
	Christoph Hellwig <hch@...radead.org>,
	David Hildenbrand <david@...hat.com>,
	"Matthew Wilcox (Oracle)" <willy@...radead.org>,
	Mark Rutland <mark.rutland@....com>,
	Anshuman Khandual <anshuman.khandual@....com>,
	Alexandre Ghiti <alexghiti@...osinc.com>,
	Kevin Brodsky <kevin.brodsky@....com>
Cc: Ryan Roberts <ryan.roberts@....com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH v3 10/11] mm/vmalloc: Enter lazy mmu mode while manipulating vmalloc ptes

Wrap vmalloc's pte table manipulation loops with
arch_enter_lazy_mmu_mode() / arch_leave_lazy_mmu_mode(). This provides
the arch code with the opportunity to optimize the pte manipulations.

Note that vmap_pfn() already uses lazy mmu mode since it delegates to
apply_to_page_range() which enters lazy mmu mode for both user and
kernel mappings.

These hooks will shortly be used by arm64 to improve vmalloc
performance.

Signed-off-by: Ryan Roberts <ryan.roberts@....com>
---
 mm/vmalloc.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 6111ce900ec4..b63ca0b7dd40 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -104,6 +104,9 @@ static int vmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 	pte = pte_alloc_kernel_track(pmd, addr, mask);
 	if (!pte)
 		return -ENOMEM;
+
+	arch_enter_lazy_mmu_mode();
+
 	do {
 		if (unlikely(!pte_none(ptep_get(pte)))) {
 			if (pfn_valid(pfn)) {
@@ -127,6 +130,8 @@ static int vmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 		set_pte_at(&init_mm, addr, pte, pfn_pte(pfn, prot));
 		pfn++;
 	} while (pte += PFN_DOWN(size), addr += size, addr != end);
+
+	arch_leave_lazy_mmu_mode();
 	*mask |= PGTBL_PTE_MODIFIED;
 	return 0;
 }
@@ -354,6 +359,8 @@ static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 	unsigned long size = PAGE_SIZE;
 
 	pte = pte_offset_kernel(pmd, addr);
+	arch_enter_lazy_mmu_mode();
+
 	do {
 #ifdef CONFIG_HUGETLB_PAGE
 		size = arch_vmap_pte_range_unmap_size(addr, pte);
@@ -370,6 +377,8 @@ static void vunmap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
 			ptent = ptep_get_and_clear(&init_mm, addr, pte);
 		WARN_ON(!pte_none(ptent) && !pte_present(ptent));
 	} while (pte += (size >> PAGE_SHIFT), addr += size, addr != end);
+
+	arch_leave_lazy_mmu_mode();
 	*mask |= PGTBL_PTE_MODIFIED;
 }
 
@@ -515,6 +524,9 @@ static int vmap_pages_pte_range(pmd_t *pmd, unsigned long addr,
 	pte = pte_alloc_kernel_track(pmd, addr, mask);
 	if (!pte)
 		return -ENOMEM;
+
+	arch_enter_lazy_mmu_mode();
+
 	do {
 		struct page *page = pages[*nr];
 
@@ -528,6 +540,8 @@ static int vmap_pages_pte_range(pmd_t *pmd, unsigned long addr,
 		set_pte_at(&init_mm, addr, pte, mk_pte(page, prot));
 		(*nr)++;
 	} while (pte++, addr += PAGE_SIZE, addr != end);
+
+	arch_leave_lazy_mmu_mode();
 	*mask |= PGTBL_PTE_MODIFIED;
 	return 0;
 }
-- 
2.43.0