linux-kernel - [PATCH v2 3/5] hugetlb: Pass struct vm_fault through to hugetlb_handle

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Date: Wed, 21 Feb 2024 15:47:30 -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,
	willy@...radead.org,
	"Vishal Moola (Oracle)" <vishal.moola@...il.com>
Subject: [PATCH v2 3/5] hugetlb: Pass struct vm_fault through to hugetlb_handle_userfault()

Now that hugetlb_fault() has a struct vm_fault, have
hugetlb_handle_userfault() use it instead of creating one of its own.

This lets us reduce the number of arguments passed to
hugetlb_handle_userfault() from 7 to 3, cleaning up the code and stack.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@...il.com>
---
 mm/hugetlb.c | 38 +++++++++-----------------------------
 1 file changed, 9 insertions(+), 29 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index d792d60ea16c..70c5870e859e 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -6060,39 +6060,21 @@ int hugetlb_add_to_page_cache(struct folio *folio, struct address_space *mapping
 	return 0;
 }
 
-static inline vm_fault_t hugetlb_handle_userfault(struct vm_area_struct *vma,
+static inline vm_fault_t hugetlb_handle_userfault(struct vm_fault *vmf,
 						  struct address_space *mapping,
-						  pgoff_t idx,
-						  unsigned int flags,
-						  unsigned long haddr,
-						  unsigned long addr,
 						  unsigned long reason)
 {
 	u32 hash;
-	struct vm_fault vmf = {
-		.vma = vma,
-		.address = haddr,
-		.real_address = addr,
-		.flags = flags,
-
-		/*
-		 * Hard to debug if it ends up being
-		 * used by a callee that assumes
-		 * something about the other
-		 * uninitialized fields... same as in
-		 * memory.c
-		 */
-	};
 
 	/*
 	 * vma_lock and hugetlb_fault_mutex must be dropped before handling
 	 * userfault. Also mmap_lock could be dropped due to handling
 	 * userfault, any vma operation should be careful from here.
 	 */
-	hugetlb_vma_unlock_read(vma);
-	hash = hugetlb_fault_mutex_hash(mapping, idx);
+	hugetlb_vma_unlock_read(vmf->vma);
+	hash = hugetlb_fault_mutex_hash(mapping, vmf->pgoff);
 	mutex_unlock(&hugetlb_fault_mutex_table[hash]);
-	return handle_userfault(&vmf, reason);
+	return handle_userfault(vmf, reason);
 }
 
 /*
@@ -6116,7 +6098,8 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
 			struct vm_area_struct *vma,
 			struct address_space *mapping, pgoff_t idx,
 			unsigned long address, pte_t *ptep,
-			pte_t old_pte, unsigned int flags)
+			pte_t old_pte, unsigned int flags,
+			struct vm_fault *vmf)
 {
 	struct hstate *h = hstate_vma(vma);
 	vm_fault_t ret = VM_FAULT_SIGBUS;
@@ -6175,8 +6158,7 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
 				goto out;
 			}
 
-			return hugetlb_handle_userfault(vma, mapping, idx, flags,
-							haddr, address,
+			return hugetlb_handle_userfault(vmf, mapping,
 							VM_UFFD_MISSING);
 		}
 
@@ -6248,8 +6230,7 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
 				ret = 0;
 				goto out;
 			}
-			return hugetlb_handle_userfault(vma, mapping, idx, flags,
-							haddr, address,
+			return hugetlb_handle_userfault(vmf, mapping,
 							VM_UFFD_MINOR);
 		}
 	}
@@ -6419,9 +6400,8 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma,
 		 * hugetlb_no_page will drop vma lock and hugetlb fault
 		 * mutex internally, which make us return immediately.
 		 */
-
 		return hugetlb_no_page(mm, vma, mapping, vmf.pgoff, address,
-					ptep, entry, flags);
+					ptep, entry, flags, &vmf);
 	}
 
 	ret = 0;
-- 
2.43.0