mm: remove VM_FAULT_WRITE

All users -- GUP and KSM -- are gone, let's just remove it.

Link: https://lkml.kernel.org/r/20221021101141.84170-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Peter Xu <peterx@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/mm_types.h

@@ -929,7 +929,6 @@ typedef __bitwise unsigned int vm_fault_t;
  * @VM_FAULT_OOM:		Out Of Memory
  * @VM_FAULT_SIGBUS:		Bad access
  * @VM_FAULT_MAJOR:		Page read from storage
- * @VM_FAULT_WRITE:		Special case for get_user_pages
  * @VM_FAULT_HWPOISON:		Hit poisoned small page
  * @VM_FAULT_HWPOISON_LARGE:	Hit poisoned large page. Index encoded
  *				in upper bits
@@ -950,7 +949,6 @@ enum vm_fault_reason {
 	VM_FAULT_OOM            = (__force vm_fault_t)0x000001,
 	VM_FAULT_SIGBUS         = (__force vm_fault_t)0x000002,
 	VM_FAULT_MAJOR          = (__force vm_fault_t)0x000004,
-	VM_FAULT_WRITE          = (__force vm_fault_t)0x000008,
 	VM_FAULT_HWPOISON       = (__force vm_fault_t)0x000010,
 	VM_FAULT_HWPOISON_LARGE = (__force vm_fault_t)0x000020,
 	VM_FAULT_SIGSEGV        = (__force vm_fault_t)0x000040,
@@ -976,7 +974,6 @@ enum vm_fault_reason {
 	{ VM_FAULT_OOM,                 "OOM" },	\
 	{ VM_FAULT_SIGBUS,              "SIGBUS" },	\
 	{ VM_FAULT_MAJOR,               "MAJOR" },	\
-	{ VM_FAULT_WRITE,               "WRITE" },	\
 	{ VM_FAULT_HWPOISON,            "HWPOISON" },	\
 	{ VM_FAULT_HWPOISON_LARGE,      "HWPOISON_LARGE" },	\
 	{ VM_FAULT_SIGSEGV,             "SIGSEGV" },	\

mm/huge_memory.c

@@ -1376,7 +1376,7 @@ reuse:
 		if (pmdp_set_access_flags(vma, haddr, vmf->pmd, entry, 1))
 			update_mmu_cache_pmd(vma, vmf->address, vmf->pmd);
 		spin_unlock(vmf->ptl);
-		return VM_FAULT_WRITE;
+		return 0;
 	}
 
 unlock_fallback:

mm/memory.c

@@ -3213,7 +3213,7 @@ static vm_fault_t wp_page_copy(struct vm_fault *vmf)
 	}
 
 	delayacct_wpcopy_end();
-	return (page_copied && !unshare) ? VM_FAULT_WRITE : 0;
+	return 0;
 oom_free_new:
 	put_page(new_page);
 oom:
@@ -3277,14 +3277,14 @@ static vm_fault_t wp_pfn_shared(struct vm_fault *vmf)
 		return finish_mkwrite_fault(vmf);
 	}
 	wp_page_reuse(vmf);
-	return VM_FAULT_WRITE;
+	return 0;
 }
 
 static vm_fault_t wp_page_shared(struct vm_fault *vmf)
 	__releases(vmf->ptl)
 {
 	struct vm_area_struct *vma = vmf->vma;
-	vm_fault_t ret = VM_FAULT_WRITE;
+	vm_fault_t ret = 0;
 
 	get_page(vmf->page);
 
@@ -3430,7 +3430,7 @@ reuse:
 			return 0;
 		}
 		wp_page_reuse(vmf);
-		return VM_FAULT_WRITE;
+		return 0;
 	}
 copy:
 	/*
@@ -3944,7 +3944,6 @@ vm_fault_t do_swap_page(struct vm_fault *vmf)
 		if (vmf->flags & FAULT_FLAG_WRITE) {
 			pte = maybe_mkwrite(pte_mkdirty(pte), vma);
 			vmf->flags &= ~FAULT_FLAG_WRITE;
-			ret |= VM_FAULT_WRITE;
 		}
 		rmap_flags |= RMAP_EXCLUSIVE;
 	}