[PATCH] mm: ia64 use expand_upwards

ia64 has expand_backing_store function for growing its Register Backing Store
vma upwards.  But more complete code for this purpose is found in the
CONFIG_STACK_GROWSUP part of mm/mmap.c.  Uglify its #ifdefs further to provide
expand_upwards for ia64 as well as expand_stack for parisc.

The Register Backing Store vma should be marked VM_ACCOUNT.  Implement the
intention of growing it only a page at a time, instead of passing an address
outside of the vma to handle_mm_fault, with unknown consequences.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c
index f21b55549787b80249a1e44430ccd3de859001a6..af7eb087dca7af7df598e8c81c475e9b365f042c 100644 (file)
--- a/arch/ia64/mm/fault.c
+++ b/arch/ia64/mm/fault.c
@@ -19,32 +19,6 @@
 
 extern void die (char *, struct pt_regs *, long);
 
-/*
- * This routine is analogous to expand_stack() but instead grows the
- * register backing store (which grows towards higher addresses).
- * Since the register backing store is access sequentially, we
- * disallow growing the RBS by more than a page at a time.  Note that
- * the VM_GROWSUP flag can be set on any VM area but that's fine
- * because the total process size is still limited by RLIMIT_STACK and
- * RLIMIT_AS.
- */
-static inline long
-expand_backing_store (struct vm_area_struct *vma, unsigned long address)
-{
-       unsigned long grow;
-
-       grow = PAGE_SIZE >> PAGE_SHIFT;
-       if (address - vma->vm_start > current->signal->rlim[RLIMIT_STACK].rlim_cur
-           || (((vma->vm_mm->total_vm + grow) << PAGE_SHIFT) > current->signal->rlim[RLIMIT_AS].rlim_cur))
-               return -ENOMEM;
-       vma->vm_end += PAGE_SIZE;
-       vma->vm_mm->total_vm += grow;
-       if (vma->vm_flags & VM_LOCKED)
-               vma->vm_mm->locked_vm += grow;
-       vm_stat_account(vma->vm_mm, vma->vm_flags, vma->vm_file, grow);
-       return 0;
-}
-
 /*
  * Return TRUE if ADDRESS points at a page in the kernel's mapped segment
  * (inside region 5, on ia64) and that page is present.
@@ -185,7 +159,13 @@ ia64_do_page_fault (unsigned long address, unsigned long isr, struct pt_regs *re
                if (REGION_NUMBER(address) != REGION_NUMBER(vma->vm_start)
                    || REGION_OFFSET(address) >= RGN_MAP_LIMIT)
                        goto bad_area;
-               if (expand_backing_store(vma, address))
+               /*
+                * Since the register backing store is accessed sequentially,
+                * we disallow growing it by more than a page at a time.
+                */
+               if (address > vma->vm_end + PAGE_SIZE - sizeof(long))
+                       goto bad_area;
+               if (expand_upwards(vma, address))
                        goto bad_area;
        }
        goto good_area;

diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c
index 98246acd4991f23d2d660389dfaa1fdf2aa76d7b..0063b2c50908dde835645e6fac08c9e2b17fb57b 100644 (file)
--- a/arch/ia64/mm/init.c
+++ b/arch/ia64/mm/init.c
@@ -158,7 +158,7 @@ ia64_init_addr_space (void)
                vma->vm_start = current->thread.rbs_bot & PAGE_MASK;
                vma->vm_end = vma->vm_start + PAGE_SIZE;
                vma->vm_page_prot = protection_map[VM_DATA_DEFAULT_FLAGS & 0x7];
-               vma->vm_flags = VM_DATA_DEFAULT_FLAGS | VM_GROWSUP;
+               vma->vm_flags = VM_DATA_DEFAULT_FLAGS|VM_GROWSUP|VM_ACCOUNT;
                down_write(&current->mm->mmap_sem);
                if (insert_vm_struct(current->mm, vma)) {
                        up_write(&current->mm->mmap_sem);

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 7d4552fe08644c1074dda8a54adae26bc5d2a0f6..89398032bc4b98731f42a8f6410527445192ee10 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -896,7 +896,8 @@ void handle_ra_miss(struct address_space *mapping,
 unsigned long max_sane_readahead(unsigned long nr);
 
 /* Do stack extension */
-extern int expand_stack(struct vm_area_struct * vma, unsigned long address);
+extern int expand_stack(struct vm_area_struct *vma, unsigned long address);
+extern int expand_upwards(struct vm_area_struct *vma, unsigned long address);
 
 /* Look up the first VMA which satisfies  addr < vm_end,  NULL if none. */
 extern struct vm_area_struct * find_vma(struct mm_struct * mm, unsigned long addr);

diff --git a/mm/mmap.c b/mm/mmap.c
index c43b284570070cb738fb8434dee7a30e406f912c..d931d7e49ac9bd09dd222279113b4829faf764e8 100644 (file)
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1508,11 +1508,15 @@ static int acct_stack_growth(struct vm_area_struct * vma, unsigned long size, un
        return 0;
 }
 
-#ifdef CONFIG_STACK_GROWSUP
+#if defined(CONFIG_STACK_GROWSUP) || defined(CONFIG_IA64)
 /*
- * vma is the first one with address > vma->vm_end.  Have to extend vma.
+ * PA-RISC uses this for its stack; IA64 for its Register Backing Store.
+ * vma is the last one with address > vma->vm_end.  Have to extend vma.
  */
-int expand_stack(struct vm_area_struct * vma, unsigned long address)
+#ifdef CONFIG_STACK_GROWSUP
+static inline
+#endif
+int expand_upwards(struct vm_area_struct *vma, unsigned long address)
 {
        int error;
 
@@ -1550,6 +1554,13 @@ int expand_stack(struct vm_area_struct * vma, unsigned long address)
        anon_vma_unlock(vma);
        return error;
 }
+#endif /* CONFIG_STACK_GROWSUP || CONFIG_IA64 */
+
+#ifdef CONFIG_STACK_GROWSUP
+int expand_stack(struct vm_area_struct *vma, unsigned long address)
+{
+       return expand_upwards(vma, address);
+}
 
 struct vm_area_struct *
 find_extend_vma(struct mm_struct *mm, unsigned long addr)