linux-kernel - [PATCH 2/3] hugetlb: Use vmf_anon_prepare() instead of anon_vma

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Message-ID: <20240220231424.126600-3-vishal.moola@gmail.com>
Date: Tue, 20 Feb 2024 15:14:23 -0800
From: "Vishal Moola (Oracle)" <vishal.moola@...il.com>
To: linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org,
	muchun.song@...ux.dev,
	"Vishal Moola (Oracle)" <vishal.moola@...il.com>
Subject: [PATCH 2/3] hugetlb: Use vmf_anon_prepare() instead of anon_vma_prepare()

hugetlb_no_page() and hugetlb_wp() call anon_vma_prepare(). In
preparation for hugetlb to safely handle faults under the VMA lock,
use vmf_anon_prepare() here instead.

Additionally, define a struct vm_fault at the top of each function.
These can later be used to convert hugetlb to use struct vm_fault -
similar to mm/memory.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@...il.com>
---
 mm/hugetlb.c | 27 +++++++++++++++++++++------
 1 file changed, 21 insertions(+), 6 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index ed1581b670d4..10f57306e1f0 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -5834,9 +5834,15 @@ static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma,
 	struct folio *old_folio;
 	struct folio *new_folio;
 	int outside_reserve = 0;
-	vm_fault_t ret = 0;
+	vm_fault_t ret = 0, anon_ret = 0;
 	unsigned long haddr = address & huge_page_mask(h);
 	struct mmu_notifier_range range;
+	struct vm_fault vmf = {
+				.vma = vma,
+				.address = haddr,
+				.real_address = address,
+				.flags = flags,
+	};
 
 	/*
 	 * Never handle CoW for uffd-wp protected pages.  It should be only
@@ -5960,8 +5966,9 @@ static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma,
 	 * When the original hugepage is shared one, it does not have
 	 * anon_vma prepared.
 	 */
-	if (unlikely(anon_vma_prepare(vma))) {
-		ret = VM_FAULT_OOM;
+	anon_ret = vmf_anon_prepare(&vmf);
+	if (unlikely(anon_ret)) {
+		ret = anon_ret;
 		goto out_release_all;
 	}
 
@@ -6119,7 +6126,7 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
 			pte_t old_pte, unsigned int flags)
 {
 	struct hstate *h = hstate_vma(vma);
-	vm_fault_t ret = VM_FAULT_SIGBUS;
+	vm_fault_t ret = VM_FAULT_SIGBUS, anon_ret = 0;
 	int anon_rmap = 0;
 	unsigned long size;
 	struct folio *folio;
@@ -6128,6 +6135,12 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
 	unsigned long haddr = address & huge_page_mask(h);
 	bool new_folio, new_pagecache_folio = false;
 	u32 hash = hugetlb_fault_mutex_hash(mapping, idx);
+	struct vm_fault vmf = {
+				.vma = vma,
+				.address = haddr,
+				.real_address = address,
+				.flags = flags,
+	};
 
 	/*
 	 * Currently, we are forced to kill the process in the event the
@@ -6221,8 +6234,10 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
 			new_pagecache_folio = true;
 		} else {
 			folio_lock(folio);
-			if (unlikely(anon_vma_prepare(vma))) {
-				ret = VM_FAULT_OOM;
+
+			anon_ret = vmf_anon_prepare(&vmf);
+			if (unlikely(anon_ret)) {
+				ret = anon_ret;
 				goto backout_unlocked;
 			}
 			anon_rmap = 1;
-- 
2.43.0