Re: [RFC][PATCH v3 09/22] mm, s390: add gfp flags variant of pud, pte, and pte allocations

[Prasad Joshi <prasadjoshi124@gmail.com>]

Generic changes
 - Added function __crst_table_alloc() which is similar to crst_table_alloc()
   but accepts an extra argument gfp_t. The function uses given allocation
   flag to allocate pages.

- The function crst_table_alloc() has been modified to call
  __crst_table_alloc() and pass GFP_KERNEL allocation flag.

- Added a function __page_table_alloc() to allocate page table entries. This
  function is allows caller to specify the page allocation flag. The
  allocation flag is then passed to alloc_page(). The rest of the function is
  copy of the original page_table_alloc().

- The function page_table_alloc() is modified to call __page_table_alloc()
  and pass GFP_KERNEL | __GFP_REPEAT allocation flags.

changes for 32 (31) bit architecture (s390)
- Added macros __pud_alloc_one, __pmd_alloc_one which are similar to
  pud_alloc_one and pmd_alloc_one respectively, but has an extra argument
  for gfp_t.

changes for 64 bit architecture (s390x)
- Added __pud_alloc_one() allow caller to pass the memory allocation flag.
  The function passes the allocation flag to __crst_table_alloc(). The rest
  of the function is copy of crst_table_alloc().

- The function pud_alloc_one() is modified to call __pud_alloc_one() and
  pass GFP_KERNEL allocation flag.

- The similar changes are performed for pmd allocations

- Added marco __pte_alloc_one_kernel() to accept additional argument gfp_t.
  This argument is then passed to __page_table_alloc() to allocate the page
  table entry.

- Modified pte_alloc_one_kernel() to call __pte_alloc_one_kernel() passing
  GFP_KERNEL|__GFP_REPEAT allocation flags.

- The changes for both architectures help in fixing Bug 30702

Signed-off-by: Prasad Joshi <prasadjoshi124@gmail.com>
Signed-off-by: Anand Mitra <mitra@kqinfotech.com>
---
 arch/s390/include/asm/pgalloc.h |   30 +++++++++++++++++++++++++-----
 arch/s390/mm/pgtable.c          |   22 +++++++++++++++++-----
 2 files changed, 42 insertions(+), 10 deletions(-)

diff --git a/arch/s390/include/asm/pgalloc.h b/arch/s390/include/asm/pgalloc.h
index 082eb4e..459e89a 100644
--- a/arch/s390/include/asm/pgalloc.h
+++ b/arch/s390/include/asm/pgalloc.h
@@ -20,10 +20,12 @@
 #define check_pgt_cache()	do {} while (0)
 
 unsigned long *crst_table_alloc(struct mm_struct *, int);
+unsigned long * __crst_table_alloc(struct mm_struct *, int , gfp_t);
 void crst_table_free(struct mm_struct *, unsigned long *);
 void crst_table_free_rcu(struct mm_struct *, unsigned long *);
 
 unsigned long *page_table_alloc(struct mm_struct *);
+unsigned long *__page_table_alloc(struct mm_struct *, gfp_t);
 void page_table_free(struct mm_struct *, unsigned long *);
 void page_table_free_rcu(struct mm_struct *, unsigned long *);
 void disable_noexec(struct mm_struct *, struct task_struct *);
@@ -62,9 +64,11 @@ static inline unsigned long pgd_entry_type(struct mm_struct *mm)
 	return _SEGMENT_ENTRY_EMPTY;
 }
 
+#define __pud_alloc_one(mm,address,mask)		({ BUG(); ((pud_t *)2); })
 #define pud_alloc_one(mm,address)		({ BUG(); ((pud_t *)2); })
 #define pud_free(mm, x)				do { } while (0)
 
+#define __pmd_alloc_one(mm,address,mask)		({ BUG(); ((pmd_t *)2); })
 #define pmd_alloc_one(mm,address)		({ BUG(); ((pmd_t *)2); })
 #define pmd_free(mm, x)				do { } while (0)
 
@@ -88,22 +92,34 @@ static inline unsigned long pgd_entry_type(struct mm_struct *mm)
 int crst_table_upgrade(struct mm_struct *, unsigned long limit);
 void crst_table_downgrade(struct mm_struct *, unsigned long limit);
 
-static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long address)
+static inline pud_t *
+__pud_alloc_one(struct mm_struct *mm, unsigned long address, gfp_t gfp_mask)
 {
-	unsigned long *table = crst_table_alloc(mm, mm->context.noexec);
+	unsigned long *table = __crst_table_alloc(mm, mm->context.noexec, gfp_mask);
 	if (table)
 		crst_table_init(table, _REGION3_ENTRY_EMPTY);
 	return (pud_t *) table;
 }
+
+static inline pud_t *pud_alloc_one(struct mm_struct *mm, unsigned long address)
+{
+	return __pud_alloc_one(mm, address, GFP_KERNEL);
+}
 #define pud_free(mm, pud) crst_table_free(mm, (unsigned long *) pud)
 
-static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long vmaddr)
+static inline pmd_t *
+__pmd_alloc_one(struct mm_struct *mm, unsigned long vmaddr, gfp_t gfp_mask)
 {
-	unsigned long *table = crst_table_alloc(mm, mm->context.noexec);
+	unsigned long *table = __crst_table_alloc(mm, mm->context.noexec, gfp_mask);
 	if (table)
 		crst_table_init(table, _SEGMENT_ENTRY_EMPTY);
 	return (pmd_t *) table;
 }
+
+static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long vmaddr)
+{
+	return __pmd_alloc_one(mm, vmaddr, GFP_KERNEL);
+}
 #define pmd_free(mm, pmd) crst_table_free(mm, (unsigned long *) pmd)
 
 static inline void pgd_populate_kernel(struct mm_struct *mm,
@@ -172,7 +188,11 @@ static inline void pmd_populate(struct mm_struct *mm,
 /*
  * page table entry allocation/free routines.
  */
-#define pte_alloc_one_kernel(mm, vmaddr) ((pte_t *) page_table_alloc(mm))
+#define __pte_alloc_one_kernel(mm, vmaddr, mask) \
+	((pte_t *) __page_table_alloc((mm), (mask)))
+#define pte_alloc_one_kernel(mm, vmaddr) \
+	((pte_t *) __pte_alloc_one_kernel((mm), (vmaddr), GFP_KERNEL|__GFP_REPEAT)
+
 #define pte_alloc_one(mm, vmaddr) ((pte_t *) page_table_alloc(mm))
 
 #define pte_free_kernel(mm, pte) page_table_free(mm, (unsigned long *) pte)
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index e1850c2..624854a 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -125,15 +125,16 @@ static int __init parse_vmalloc(char *arg)
 }
 early_param("vmalloc", parse_vmalloc);
 
-unsigned long *crst_table_alloc(struct mm_struct *mm, int noexec)
+unsigned long *
+__crst_table_alloc(struct mm_struct *mm, int noexec, gfp_t gfp_mask)
 {
-	struct page *page = alloc_pages(GFP_KERNEL, ALLOC_ORDER);
+	struct page *page = alloc_pages(gfp_mask, ALLOC_ORDER);
 
 	if (!page)
 		return NULL;
 	page->index = 0;
 	if (noexec) {
-		struct page *shadow = alloc_pages(GFP_KERNEL, ALLOC_ORDER);
+		struct page *shadow = alloc_pages(gfp_mask, ALLOC_ORDER);
 		if (!shadow) {
 			__free_pages(page, ALLOC_ORDER);
 			return NULL;
@@ -146,6 +147,11 @@ unsigned long *crst_table_alloc(struct mm_struct *mm, int noexec)
 	return (unsigned long *) page_to_phys(page);
 }
 
+unsigned long *crst_table_alloc(struct mm_struct *mm, int noexec)
+{
+	return __crst_table_alloc(mm, noexec, GFP_KERNEL);
+}
+
 static void __crst_table_free(struct mm_struct *mm, unsigned long *table)
 {
 	unsigned long *shadow = get_shadow_table(table);
@@ -267,7 +273,7 @@ void crst_table_downgrade(struct mm_struct *mm, unsigned long limit)
 /*
  * page table entry allocation/free routines.
  */
-unsigned long *page_table_alloc(struct mm_struct *mm)
+unsigned long *__page_table_alloc(struct mm_struct *mm, gfp_t gfp_mask)
 {
 	struct page *page;
 	unsigned long *table;
@@ -284,7 +290,7 @@ unsigned long *page_table_alloc(struct mm_struct *mm)
 	}
 	if (!page) {
 		spin_unlock_bh(&mm->context.list_lock);
-		page = alloc_page(GFP_KERNEL|__GFP_REPEAT);
+		page = alloc_page(gfp_mask);
 		if (!page)
 			return NULL;
 		pgtable_page_ctor(page);
@@ -309,6 +315,12 @@ unsigned long *page_table_alloc(struct mm_struct *mm)
 	return table;
 }
 
+
+unsigned long *page_table_alloc(struct mm_struct *mm)
+{
+	return __page_table_alloc(mm, GFP_KERNEL | __GFP_REPEAT);
+}
+
 static void __page_table_free(struct mm_struct *mm, unsigned long *table)
 {
 	struct page *page;
-- 
1.7.0.4