lkml.org 
[lkml]   [2008]   [Mar]   [17]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH] [11/18] Fix alignment bug in bootmem allocator
On Mon, Mar 17, 2008 at 11:52 AM, Yinghai Lu <yhlu.kernel@gmail.com> wrote:
> On Mon, Mar 17, 2008 at 1:56 AM, Andi Kleen <andi@firstfloor.org> wrote:
> > > only happen when align is large than alignment of node_boot_start.
> >
> > Here's an updated version of the patch with this addressed.
> > Please review. The patch is somewhat more complicated, but
> > actually makes the code a little cleaner now.
> >
> > -Andi
> >
> >
> > Fix alignment bug in bootmem allocator
> >
> >
> > Without this fix bootmem can return unaligned addresses when the start of a
> > node is not aligned to the align value. Needed for reliably allocating
> > gigabyte pages.
> >
> > I removed the offset variable because all tests should align themself correctly
> > now. Slight drawback might be that the bootmem allocator will spend
> > some more time skipping bits in the bitmap initially, but that shouldn't
> > be a big issue.
> >
> >
> > Signed-off-by: Andi Kleen <ak@suse.de>
> >
> how about create local node_boot_start and node_bootmem_map that make
> sure node_boot_start has bigger alignment than align input.

please check it

YH
[PATCH] mm: offset align in alloc_bootmem v2

need offset alignment when node_boot_start's alignment is less than
align required

v2: use local node_boot_start to match align.

Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>

Index: linux-2.6/mm/bootmem.c
===================================================================
--- linux-2.6.orig/mm/bootmem.c
+++ linux-2.6/mm/bootmem.c
@@ -206,9 +206,11 @@ void * __init
__alloc_bootmem_core(struct bootmem_data *bdata, unsigned long size,
unsigned long align, unsigned long goal, unsigned long limit)
{
- unsigned long offset, remaining_size, areasize, preferred;
+ unsigned long areasize, preferred;
unsigned long i, start = 0, incr, eidx, end_pfn;
void *ret;
+ unsigned long node_boot_start;
+ void *node_bootmem_map;

if (!size) {
printk("__alloc_bootmem_core(): zero-sized request\n");
@@ -216,23 +218,29 @@ __alloc_bootmem_core(struct bootmem_data
}
BUG_ON(align & (align-1));

- if (limit && bdata->node_boot_start >= limit)
- return NULL;
-
/* on nodes without memory - bootmem_map is NULL */
if (!bdata->node_bootmem_map)
return NULL;

+ /* bdata->node_boot_start is supposed to be (12+6)bits alignment ? */
+ if (align && ffs(align) > ffs(bdata->node_boot_start)) {
+ node_boot_start = ALIGN(bdata->node_boot_start, align);
+ node_bootmem_map = (unsigned char *)bdata->node_bootmem_map +
+ PFN_DOWN(node_boot_start - bdata->node_boot_start)/BITS_PER_LONG;
+ } else {
+ node_boot_start = bdata->node_boot_start;
+ node_bootmem_map = bdata->node_bootmem_map;
+ }
+
+ if (limit && node_boot_start >= limit)
+ return NULL;
+
end_pfn = bdata->node_low_pfn;
limit = PFN_DOWN(limit);
if (limit && end_pfn > limit)
end_pfn = limit;

- eidx = end_pfn - PFN_DOWN(bdata->node_boot_start);
- offset = 0;
- if (align && (bdata->node_boot_start & (align - 1UL)) != 0)
- offset = align - (bdata->node_boot_start & (align - 1UL));
- offset = PFN_DOWN(offset);
+ eidx = end_pfn - PFN_DOWN(node_boot_start);

/*
* We try to allocate bootmem pages above 'goal'
@@ -240,15 +248,15 @@ __alloc_bootmem_core(struct bootmem_data
*/
preferred = 0;
if (goal && PFN_DOWN(goal) < end_pfn) {
- if (goal > bdata->node_boot_start)
- preferred = goal - bdata->node_boot_start;
+ if (goal > node_boot_start)
+ preferred = goal - node_boot_start;

if (bdata->last_success >= preferred)
if (!limit || (limit && limit > bdata->last_success))
preferred = bdata->last_success;
}

- preferred = PFN_DOWN(ALIGN(preferred, align)) + offset;
+ preferred = PFN_DOWN(ALIGN(preferred, align));
areasize = (size + PAGE_SIZE-1) / PAGE_SIZE;
incr = align >> PAGE_SHIFT ? : 1;

@@ -256,18 +264,18 @@ restart_scan:
for (i = preferred; i < eidx;) {
unsigned long j;

- i = find_next_zero_bit(bdata->node_bootmem_map, eidx, i);
+ i = find_next_zero_bit(node_bootmem_map, eidx, i);
i = ALIGN(i, incr);
if (i >= eidx)
break;
- if (test_bit(i, bdata->node_bootmem_map)) {
+ if (test_bit(i, node_bootmem_map)) {
i += incr;
continue;
}
for (j = i + 1; j < i + areasize; ++j) {
if (j >= eidx)
goto fail_block;
- if (test_bit(j, bdata->node_bootmem_map))
+ if (test_bit(j, node_bootmem_map))
goto fail_block;
}
start = i;
@@ -278,8 +286,8 @@ restart_scan:
i += incr;
}

- if (preferred > offset) {
- preferred = offset;
+ if (preferred > 0) {
+ preferred = 0;
goto restart_scan;
}
return NULL;
@@ -295,6 +303,7 @@ found:
*/
if (align < PAGE_SIZE &&
bdata->last_offset && bdata->last_pos+1 == start) {
+ unsigned long offset, remaining_size;
offset = ALIGN(bdata->last_offset, align);
BUG_ON(offset > PAGE_SIZE);
remaining_size = PAGE_SIZE - offset;
@@ -303,14 +312,12 @@ found:
/* last_pos unchanged */
bdata->last_offset = offset + size;
ret = phys_to_virt(bdata->last_pos * PAGE_SIZE +
- offset +
- bdata->node_boot_start);
+ offset + node_boot_start);
} else {
remaining_size = size - remaining_size;
areasize = (remaining_size + PAGE_SIZE-1) / PAGE_SIZE;
ret = phys_to_virt(bdata->last_pos * PAGE_SIZE +
- offset +
- bdata->node_boot_start);
+ offset + node_boot_start);
bdata->last_pos = start + areasize - 1;
bdata->last_offset = remaining_size;
}
@@ -318,14 +325,14 @@ found:
} else {
bdata->last_pos = start + areasize - 1;
bdata->last_offset = size & ~PAGE_MASK;
- ret = phys_to_virt(start * PAGE_SIZE + bdata->node_boot_start);
+ ret = phys_to_virt(start * PAGE_SIZE + node_boot_start);
}

/*
* Reserve the area now:
*/
for (i = start; i < start + areasize; i++)
- if (unlikely(test_and_set_bit(i, bdata->node_bootmem_map)))
+ if (unlikely(test_and_set_bit(i, node_bootmem_map)))
BUG();
memset(ret, 0, size);
return ret;
\
 
 \ /
  Last update: 2008-03-17 22:29    [W:0.083 / U:1.944 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site