diff mbox series

[7/7] riscv: mm: Pre-allocate vmalloc PGD leaves

Message ID 20230512145737.985671-8-bjorn@kernel.org (mailing list archive)
State Changes Requested
Headers show
Series riscv: Memory Hot(Un)Plug support | expand

Checks

Context Check Description
conchuod/cover_letter success Series has a cover letter
conchuod/tree_selection success Guessed tree name to be for-next at HEAD ac9a78681b92
conchuod/fixes_present success Fixes tag not required for -next series
conchuod/maintainers_pattern success MAINTAINERS pattern errors before the patch: 6 and now 6
conchuod/verify_signedoff success Signed-off-by tag matches author and committer
conchuod/kdoc success Errors and warnings before: 0 this patch: 0
conchuod/build_rv64_clang_allmodconfig success Errors and warnings before: 8 this patch: 8
conchuod/module_param success Was 0 now: 0
conchuod/build_rv64_gcc_allmodconfig success Errors and warnings before: 9 this patch: 9
conchuod/build_rv32_defconfig fail Build failed
conchuod/dtb_warn_rv64 success Errors and warnings before: 3 this patch: 3
conchuod/header_inline success No static functions without inline keyword in header files
conchuod/checkpatch warning CHECK: Unnecessary parentheses around 'addr < VMALLOC_END' CHECK: Unnecessary parentheses around 'addr >= VMALLOC_START'
conchuod/build_rv64_nommu_k210_defconfig success Build OK
conchuod/verify_fixes success No Fixes tag
conchuod/build_rv64_nommu_virt_defconfig success Build OK

Commit Message

Björn Töpel May 12, 2023, 2:57 p.m. UTC 
From: Björn Töpel <bjorn@rivosinc.com>

Instead of relying on vmalloc_fault() to synchronize the page-tables,
pre-allocate the PGD leaves of the vmalloc area. This is only enabled
if memory hot/add is enabled by the build.

Signed-off-by: Björn Töpel <bjorn@rivosinc.com>
---
 arch/riscv/mm/fault.c | 7 ++++++-
 arch/riscv/mm/init.c  | 1 +
 2 files changed, 7 insertions(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/arch/riscv/mm/fault.c b/arch/riscv/mm/fault.c
index 8685f85a7474..b61e279acd50 100644
--- a/arch/riscv/mm/fault.c
+++ b/arch/riscv/mm/fault.c
@@ -233,12 +233,17 @@  void handle_page_fault(struct pt_regs *regs)
 	 * Fault-in kernel-space virtual memory on-demand.
 	 * The 'reference' page table is init_mm.pgd.
 	 *
+	 * For memory hotplug enabled systems, the PGD entries are
+	 * pre-allocated, which avoids the need to synchronize
+	 * pgd/fault-in.
+	 *
 	 * NOTE! We MUST NOT take any locks for this case. We may
 	 * be in an interrupt or a critical region, and should
 	 * only copy the information from the master page table,
 	 * nothing more.
 	 */
-	if (unlikely((addr >= VMALLOC_START) && (addr < VMALLOC_END))) {
+	if (unlikely(!IS_ENABLED(CONFIG_MEMORY_HOTPLUG) &&
+		     (addr >= VMALLOC_START) && (addr < VMALLOC_END))) {
 		vmalloc_fault(regs, code, addr);
 		return;
 	}
diff --git a/arch/riscv/mm/init.c b/arch/riscv/mm/init.c
index a468708d1e1c..fd5a6d3fe182 100644
--- a/arch/riscv/mm/init.c
+++ b/arch/riscv/mm/init.c
@@ -236,6 +236,7 @@  static void __init preallocate_pgd_pages_range(unsigned long start, unsigned lon
 static void __init prepare_memory_hotplug(void)
 {
 #ifdef CONFIG_MEMORY_HOTPLUG
+	preallocate_pgd_pages_range(VMALLOC_START, VMALLOC_END, "vmalloc");
 	preallocate_pgd_pages_range(VMEMMAP_START, VMEMMAP_END, "vmemmap");
 	preallocate_pgd_pages_range(PAGE_OFFSET, PAGE_END, "direct map");
 #endif