Commit f1dfe022 authored by Andrew Morton's avatar Andrew Morton Committed by Linus Torvalds

[PATCH] Use names, not numbers for pagefault types

This is Bill Irwin's cleanup patch which gives symbolic names to the
fault types:

	#define VM_FAULT_OOM	(-1)
	#define VM_FAULT_SIGBUS	0
	#define VM_FAULT_MINOR	1
	#define VM_FAULT_MAJOR	2

Only arch/i386 has been updated - other architectures can do this too.
parent 5feb041e
......@@ -56,12 +56,16 @@ int __verify_write(const void * addr, unsigned long size)
for (;;) {
survive:
{
int fault = handle_mm_fault(current->mm, vma, start, 1);
if (!fault)
switch (handle_mm_fault(current->mm, vma, start, 1)) {
case VM_FAULT_SIGBUS:
goto bad_area;
if (fault < 0)
case VM_FAULT_OOM:
goto out_of_memory;
case VM_FAULT_MINOR:
case VM_FAULT_MAJOR:
break;
default:
BUG();
}
if (!size)
break;
......@@ -239,16 +243,18 @@ asmlinkage void do_page_fault(struct pt_regs *regs, unsigned long error_code)
* the fault.
*/
switch (handle_mm_fault(mm, vma, address, write)) {
case 1:
case VM_FAULT_MINOR:
tsk->min_flt++;
break;
case 2:
case VM_FAULT_MAJOR:
tsk->maj_flt++;
break;
case 0:
case VM_FAULT_SIGBUS:
goto do_sigbus;
default:
case VM_FAULT_OOM:
goto out_of_memory;
default:
BUG();
}
/*
......
......@@ -305,6 +305,16 @@ static inline void set_page_zone(struct page *page, unsigned long zone_num)
#define NOPAGE_SIGBUS (NULL)
#define NOPAGE_OOM ((struct page *) (-1))
/*
* Different kinds of faults, as returned by handle_mm_fault().
* Used to decide whether a process gets delivered SIGBUS or
* just gets major/minor fault counters bumped up.
*/
#define VM_FAULT_OOM (-1)
#define VM_FAULT_SIGBUS 0
#define VM_FAULT_MINOR 1
#define VM_FAULT_MAJOR 2
/* The array of struct pages */
extern struct page *mem_map;
......
......@@ -503,18 +503,18 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm, unsigned long
while (!(map = follow_page(mm, start, write))) {
spin_unlock(&mm->page_table_lock);
switch (handle_mm_fault(mm, vma, start, write)) {
case 1:
case VM_FAULT_MINOR:
tsk->min_flt++;
break;
case 2:
case VM_FAULT_MAJOR:
tsk->maj_flt++;
break;
case 0:
if (i) return i;
return -EFAULT;
case VM_FAULT_SIGBUS:
return i ? i : -EFAULT;
case VM_FAULT_OOM:
return i ? i : -ENOMEM;
default:
if (i) return i;
return -ENOMEM;
BUG();
}
spin_lock(&mm->page_table_lock);
}
......@@ -968,7 +968,7 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct * vma,
establish_pte(vma, address, page_table, pte_mkyoung(pte_mkdirty(pte_mkwrite(pte))));
pte_unmap(page_table);
spin_unlock(&mm->page_table_lock);
return 1; /* Minor fault */
return VM_FAULT_MINOR;
}
}
pte_unmap(page_table);
......@@ -1002,16 +1002,21 @@ static int do_wp_page(struct mm_struct *mm, struct vm_area_struct * vma,
spin_unlock(&mm->page_table_lock);
page_cache_release(new_page);
page_cache_release(old_page);
return 1; /* Minor fault */
return VM_FAULT_MINOR;
bad_wp_page:
pte_unmap(page_table);
spin_unlock(&mm->page_table_lock);
printk(KERN_ERR "do_wp_page: bogus page at address %08lx\n", address);
return -1;
/*
* This should really halt the system so it can be debugged or
* at least the kernel stops what it's doing before it corrupts
* data, but for the moment just pretend this is OOM.
*/
return VM_FAULT_OOM;
no_mem:
page_cache_release(old_page);
return -1;
return VM_FAULT_OOM;
}
static void vmtruncate_list(list_t *head, unsigned long pgoff)
......@@ -1135,7 +1140,7 @@ static int do_swap_page(struct mm_struct * mm,
struct page *page;
swp_entry_t entry = pte_to_swp_entry(orig_pte);
pte_t pte;
int ret = 1;
int ret = VM_FAULT_MINOR;
pte_unmap(page_table);
spin_unlock(&mm->page_table_lock);
......@@ -1148,17 +1153,19 @@ static int do_swap_page(struct mm_struct * mm,
* Back out if somebody else faulted in this pte while
* we released the page table lock.
*/
int retval;
spin_lock(&mm->page_table_lock);
page_table = pte_offset_map(pmd, address);
retval = pte_same(*page_table, orig_pte) ? -1 : 1;
if (pte_same(*page_table, orig_pte))
ret = VM_FAULT_OOM;
else
ret = VM_FAULT_MINOR;
pte_unmap(page_table);
spin_unlock(&mm->page_table_lock);
return retval;
return ret;
}
/* Had to read the page from swap area: Major fault */
ret = 2;
ret = VM_FAULT_MAJOR;
}
lock_page(page);
......@@ -1174,7 +1181,7 @@ static int do_swap_page(struct mm_struct * mm,
spin_unlock(&mm->page_table_lock);
unlock_page(page);
page_cache_release(page);
return 1;
return VM_FAULT_MINOR;
}
/* The page isn't present yet, go ahead with the fault. */
......@@ -1232,7 +1239,7 @@ static int do_anonymous_page(struct mm_struct * mm, struct vm_area_struct * vma,
pte_unmap(page_table);
page_cache_release(page);
spin_unlock(&mm->page_table_lock);
return 1;
return VM_FAULT_MINOR;
}
mm->rss++;
flush_page_to_ram(page);
......@@ -1246,10 +1253,10 @@ static int do_anonymous_page(struct mm_struct * mm, struct vm_area_struct * vma,
/* No need to invalidate - it was non-present before */
update_mmu_cache(vma, addr, entry);
spin_unlock(&mm->page_table_lock);
return 1; /* Minor fault */
return VM_FAULT_MINOR;
no_mem:
return -1;
return VM_FAULT_OOM;
}
/*
......@@ -1277,10 +1284,11 @@ static int do_no_page(struct mm_struct * mm, struct vm_area_struct * vma,
new_page = vma->vm_ops->nopage(vma, address & PAGE_MASK, 0);
if (new_page == NULL) /* no page was available -- SIGBUS */
return 0;
/* no page was available -- either SIGBUS or OOM */
if (new_page == NOPAGE_SIGBUS)
return VM_FAULT_SIGBUS;
if (new_page == NOPAGE_OOM)
return -1;
return VM_FAULT_OOM;
/*
* Should we do an early C-O-W break?
......@@ -1289,7 +1297,7 @@ static int do_no_page(struct mm_struct * mm, struct vm_area_struct * vma,
struct page * page = alloc_page(GFP_HIGHUSER);
if (!page) {
page_cache_release(new_page);
return -1;
return VM_FAULT_OOM;
}
copy_user_highpage(page, new_page, address);
page_cache_release(new_page);
......@@ -1325,13 +1333,13 @@ static int do_no_page(struct mm_struct * mm, struct vm_area_struct * vma,
pte_unmap(page_table);
page_cache_release(new_page);
spin_unlock(&mm->page_table_lock);
return 1;
return VM_FAULT_MINOR;
}
/* no need to invalidate: a not-present page shouldn't be cached */
update_mmu_cache(vma, address, entry);
spin_unlock(&mm->page_table_lock);
return 2; /* Major fault */
return VM_FAULT_MAJOR;
}
/*
......@@ -1383,7 +1391,7 @@ static inline int handle_pte_fault(struct mm_struct *mm,
establish_pte(vma, address, pte, entry);
pte_unmap(pte);
spin_unlock(&mm->page_table_lock);
return 1;
return VM_FAULT_MINOR;
}
/*
......@@ -1411,7 +1419,7 @@ int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct * vma,
return handle_pte_fault(mm, vma, address, write_access, pte, pmd);
}
spin_unlock(&mm->page_table_lock);
return -1;
return VM_FAULT_OOM;
}
/*
......
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