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mm: correct comments regarding do_fault_around() 

There are multiple comments surrounding do_fault_around that memtion
fault_around_pages() and fault_around_mask(), two routines that do not
exist.  These comments should be reworded to reference
fault_around_bytes, the value which is used to determine how much
do_fault_around() will attempt to read when processing a fault.

These comments should have been updated when fault_around_pages() and
fault_around_mask() were removed in commit aecd6f4426 ("mm: close race
between do_fault_around() and fault_around_bytes_set()").

Fixes: aecd6f4426 ("mm: close race between do_fault_around() and fault_around_bytes_set()")
Link: http://lkml.kernel.org/r/302D0B14-C7E9-44C6-8BED-033F9ACBD030@oracle.com
Signed-off-by: William Kucharski <william.kucharski@oracle.com>
Reviewed-by: Larry Bassel <larry.bassel@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
William Kucharski 2018-01-31 16:21:11 -08:00 committed by Linus Torvalds
parent 859d4adc34
commit da391d640c
1 changed files with 11 additions and 11 deletions
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22
mm/memory.c
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@ -3511,9 +3511,8 @@ static int fault_around_bytes_get(void *data, u64 *val)
}
/*
* fault_around_pages() and fault_around_mask() expects fault_around_bytes
* rounded down to nearest page order. It's what do_fault_around() expects to
* see.
* fault_around_bytes must be rounded down to the nearest page order as it's
* what do_fault_around() expects to see.
*/
static int fault_around_bytes_set(void *data, u64 val)
{
@ -3556,13 +3555,14 @@ late_initcall(fault_around_debugfs);
* This function doesn't cross the VMA boundaries, in order to call map_pages()
* only once.
*
* fault_around_pages() defines how many pages we'll try to map.
* do_fault_around() expects it to return a power of two less than or equal to
* PTRS_PER_PTE.
* fault_around_bytes defines how many bytes we'll try to map.
* do_fault_around() expects it to be set to a power of two less than or equal
* to PTRS_PER_PTE.
*
* The virtual address of the area that we map is naturally aligned to the
* fault_around_pages() value (and therefore to page order). This way it's
* easier to guarantee that we don't cross page table boundaries.
* The virtual address of the area that we map is naturally aligned to
* fault_around_bytes rounded down to the machine page size
* (and therefore to page order). This way it's easier to guarantee
* that we don't cross page table boundaries.
*/
static int do_fault_around(struct vm_fault *vmf)
{
@ -3579,8 +3579,8 @@ static int do_fault_around(struct vm_fault *vmf)
start_pgoff -= off;
/*
* end_pgoff is either end of page table or end of vma
* or fault_around_pages() from start_pgoff, depending what is nearest.
* end_pgoff is either the end of the page table, the end of
* the vma or nr_pages from start_pgoff, depending what is nearest.
*/
end_pgoff = start_pgoff -
((vmf->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +