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mm: sparse: fix usemap allocation above node descriptor section 

After commit f5bf18fa22 ("bootmem/sparsemem: remove limit constraint
in alloc_bootmem_section"), usemap allocations may easily be placed
outside the optimal section that holds the node descriptor, even if
there is space available in that section.  This results in unnecessary
hotplug dependencies that need to have the node unplugged before the
section holding the usemap.

The reason is that the bootmem allocator doesn't guarantee a linear
search starting from the passed allocation goal but may start out at a
much higher address absent an upper limit.

Fix this by trying the allocation with the limit at the section end,
then retry without if that fails.  This keeps the fix from f5bf18fa22
of not panicking if the allocation does not fit in the section, but
still makes sure to try to stay within the section at first.

Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org>	[3.3.x, 3.4.x]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Yinghai Lu 2012-07-11 14:02:53 -07:00 committed by Linus Torvalds
parent 07b4e2bc9c
commit 99ab7b1944
4 changed files with 20 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
include/linux/bootmem.h
View File

@ -91,6 +91,11 @@ extern void *__alloc_bootmem_node_nopanic(pg_data_t *pgdat,
unsigned long size,
unsigned long align,
unsigned long goal);
void *___alloc_bootmem_node_nopanic(pg_data_t *pgdat,
unsigned long size,
unsigned long align,
unsigned long goal,
unsigned long limit);
extern void *__alloc_bootmem_low(unsigned long size,
unsigned long align,
unsigned long goal);

2
mm/bootmem.c
View File

@ -698,7 +698,7 @@ void * __init __alloc_bootmem(unsigned long size, unsigned long align,
return ___alloc_bootmem(size, align, goal, limit);
}
static void * __init ___alloc_bootmem_node_nopanic(pg_data_t *pgdat,
void * __init ___alloc_bootmem_node_nopanic(pg_data_t *pgdat,
unsigned long size, unsigned long align,
unsigned long goal, unsigned long limit)
{

2
mm/nobootmem.c
View File

@ -274,7 +274,7 @@ void * __init __alloc_bootmem(unsigned long size, unsigned long align,
return ___alloc_bootmem(size, align, goal, limit);
}
static void * __init ___alloc_bootmem_node_nopanic(pg_data_t *pgdat,
void * __init ___alloc_bootmem_node_nopanic(pg_data_t *pgdat,
unsigned long size,
unsigned long align,
unsigned long goal,

18
mm/sparse.c
View File

@ -275,8 +275,9 @@ static unsigned long * __init
sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
unsigned long size)
{
pg_data_t *host_pgdat;
unsigned long goal;
unsigned long goal, limit;
unsigned long *p;
int nid;
/*
* A page may contain usemaps for other sections preventing the
* page being freed and making a section unremovable while
@ -288,9 +289,16 @@ sparse_early_usemaps_alloc_pgdat_section(struct pglist_data *pgdat,
* this problem.
*/
goal = __pa(pgdat) & (PAGE_SECTION_MASK << PAGE_SHIFT);
host_pgdat = NODE_DATA(early_pfn_to_nid(goal >> PAGE_SHIFT));
return __alloc_bootmem_node_nopanic(host_pgdat, size,
SMP_CACHE_BYTES, goal);
limit = goal + (1UL << PA_SECTION_SHIFT);
nid = early_pfn_to_nid(goal >> PAGE_SHIFT);
again:
p = ___alloc_bootmem_node_nopanic(NODE_DATA(nid), size,
SMP_CACHE_BYTES, goal, limit);
if (!p && limit) {
limit = 0;
goto again;
}
return p;
}
static void __init check_usemap_section_nr(int nid, unsigned long *usemap)