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mm: add debugfs tunable for fault_around_order 

Let's allow people to tweak faultaround at runtime.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Matthew Wilcox <matthew.r.wilcox@intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Ning Qu <quning@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov 2014-04-07 15:37:22 -07:00 committed by Linus Torvalds
parent 99e3e53f4e
commit 1592eef015
1 changed files with 61 additions and 7 deletions
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68
mm/memory.c
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@ -60,6 +60,7 @@
#include <linux/migrate.h>
#include <linux/string.h>
#include <linux/dma-debug.h>
#include <linux/debugfs.h>
#include <asm/io.h>
#include <asm/pgalloc.h>
@ -3382,8 +3383,63 @@ void do_set_pte(struct vm_area_struct *vma, unsigned long address,
}
#define FAULT_AROUND_ORDER 4
#define FAULT_AROUND_PAGES (1UL << FAULT_AROUND_ORDER)
#define FAULT_AROUND_MASK ~((1UL << (PAGE_SHIFT + FAULT_AROUND_ORDER)) - 1)
#ifdef CONFIG_DEBUG_FS
static unsigned int fault_around_order = FAULT_AROUND_ORDER;
static int fault_around_order_get(void *data, u64 *val)
{
*val = fault_around_order;
return 0;
}
static int fault_around_order_set(void *data, u64 val)
{
BUILD_BUG_ON((1UL << FAULT_AROUND_ORDER) > PTRS_PER_PTE);
if (1UL << val > PTRS_PER_PTE)
return -EINVAL;
fault_around_order = val;
return 0;
}
DEFINE_SIMPLE_ATTRIBUTE(fault_around_order_fops,
fault_around_order_get, fault_around_order_set, "%llu\n");
static int __init fault_around_debugfs(void)
{
void *ret;
ret = debugfs_create_file("fault_around_order", 0644, NULL, NULL,
&fault_around_order_fops);
if (!ret)
pr_warn("Failed to create fault_around_order in debugfs");
return 0;
}
late_initcall(fault_around_debugfs);
static inline unsigned long fault_around_pages(void)
{
return 1UL << fault_around_order;
}
static inline unsigned long fault_around_mask(void)
{
return ~((1UL << (PAGE_SHIFT + fault_around_order)) - 1);
}
#else
static inline unsigned long fault_around_pages(void)
{
unsigned long nr_pages;
nr_pages = 1UL << FAULT_AROUND_ORDER;
BUILD_BUG_ON(nr_pages > PTRS_PER_PTE);
return nr_pages;
}
static inline unsigned long fault_around_mask(void)
{
return ~((1UL << (PAGE_SHIFT + FAULT_AROUND_ORDER)) - 1);
}
#endif
static void do_fault_around(struct vm_area_struct *vma, unsigned long address,
pte_t *pte, pgoff_t pgoff, unsigned int flags)
@ -3393,21 +3449,19 @@ static void do_fault_around(struct vm_area_struct *vma, unsigned long address,
struct vm_fault vmf;
int off;
BUILD_BUG_ON(FAULT_AROUND_PAGES > PTRS_PER_PTE);
start_addr = max(address & FAULT_AROUND_MASK, vma->vm_start);
start_addr = max(address & fault_around_mask(), vma->vm_start);
off = ((address - start_addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
pte -= off;
pgoff -= off;
/*
* max_pgoff is either end of page table or end of vma
* or FAULT_AROUND_PAGES from pgoff, depending what is neast.
* or fault_around_pages() from pgoff, depending what is neast.
*/
max_pgoff = pgoff - ((start_addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
PTRS_PER_PTE - 1;
max_pgoff = min3(max_pgoff, vma_pages(vma) + vma->vm_pgoff - 1,
pgoff + FAULT_AROUND_PAGES - 1);
pgoff + fault_around_pages() - 1);
/* Check if it makes any sense to call ->map_pages */
while (!pte_none(*pte)) {