* [patch 27/27] Use names, not numbers for pagefault types
@ 2002-07-04 23:55 Andrew Morton
0 siblings, 0 replies; only message in thread
From: Andrew Morton @ 2002-07-04 23:55 UTC (permalink / raw)
To: Linus Torvalds; +Cc: lkml
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.
arch/i386/mm/fault.c | 34 +++++++++++++++------------
include/linux/mm.h | 10 +++++++
mm/memory.c | 64 ++++++++++++++++++++++++++++-----------------------
3 files changed, 66 insertions(+), 42 deletions(-)
--- 2.5.24/include/linux/mm.h~fault-type-cleanup Thu Jul 4 16:17:35 2002
+++ 2.5.24-akpm/include/linux/mm.h Thu Jul 4 16:17:35 2002
@@ -305,6 +305,16 @@ static inline void set_page_zone(struct
#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;
--- 2.5.24/mm/memory.c~fault-type-cleanup Thu Jul 4 16:17:35 2002
+++ 2.5.24-akpm/mm/memory.c Thu Jul 4 16:17:35 2002
@@ -503,18 +503,18 @@ int get_user_pages(struct task_struct *t
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 *
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 *
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
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
* 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
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_s
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_s
/* 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 *
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 *
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 *
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(struc
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
return handle_pte_fault(mm, vma, address, write_access, pte, pmd);
}
spin_unlock(&mm->page_table_lock);
- return -1;
+ return VM_FAULT_OOM;
}
/*
--- 2.5.24/arch/i386/mm/fault.c~fault-type-cleanup Thu Jul 4 16:17:35 2002
+++ 2.5.24-akpm/arch/i386/mm/fault.c Thu Jul 4 16:17:35 2002
@@ -56,12 +56,16 @@ good_area:
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 @@ good_area:
* the fault.
*/
switch (handle_mm_fault(mm, vma, address, write)) {
- case 1:
- tsk->min_flt++;
- break;
- case 2:
- tsk->maj_flt++;
- break;
- case 0:
- goto do_sigbus;
- default:
- goto out_of_memory;
+ case VM_FAULT_MINOR:
+ tsk->min_flt++;
+ break;
+ case VM_FAULT_MAJOR:
+ tsk->maj_flt++;
+ break;
+ case VM_FAULT_SIGBUS:
+ goto do_sigbus;
+ case VM_FAULT_OOM:
+ goto out_of_memory;
+ default:
+ BUG();
}
/*
-
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2002-07-04 23:55 [patch 27/27] Use names, not numbers for pagefault types Andrew Morton
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