memblock: free allocated memblock_reserved_regions later
memblock_free_reserved_regions() calls memblock_free(), but
memblock_free() would double reserved.regions too, so we could free the
old range for reserved.regions.
Also tj said there is another bug which could be related to this.
| I don't think we're saving any noticeable
| amount by doing this "free - give it to page allocator - reserve
| again" dancing. We should just allocate regions aligned to page
| boundaries and free them later when memblock is no longer in use.
in that case, when DEBUG_PAGEALLOC, will get panic:
memblock_free: [0x0000102febc080-0x0000102febf080] memblock_free_reserved_regions+0x37/0x39
BUG: unable to handle kernel paging request at ffff88102febd948
IP: [<ffffffff836a5774>] __next_free_mem_range+0x9b/0x155
PGD 4826063 PUD cf67a067 PMD cf7fa067 PTE 800000102febd160
Oops: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC
CPU 0
Pid: 0, comm: swapper Not tainted 3.5.0-rc2-next-20120614-sasha #447
RIP: 0010:[<ffffffff836a5774>] [<ffffffff836a5774>] __next_free_mem_range+0x9b/0x155
See the discussion at https://lkml.org/lkml/2012/6/13/469
So try to allocate with PAGE_SIZE alignment and free it later.
Reported-by: Sasha Levin <levinsasha928@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/nobootmem.c b/mm/nobootmem.c
index 0900b39..4055730 100644
--- a/mm/nobootmem.c
+++ b/mm/nobootmem.c
@@ -105,27 +105,35 @@
__free_pages_bootmem(pfn_to_page(i), 0);
}
+static unsigned long __init __free_memory_core(phys_addr_t start,
+ phys_addr_t end)
+{
+ unsigned long start_pfn = PFN_UP(start);
+ unsigned long end_pfn = min_t(unsigned long,
+ PFN_DOWN(end), max_low_pfn);
+
+ if (start_pfn > end_pfn)
+ return 0;
+
+ __free_pages_memory(start_pfn, end_pfn);
+
+ return end_pfn - start_pfn;
+}
+
unsigned long __init free_low_memory_core_early(int nodeid)
{
unsigned long count = 0;
- phys_addr_t start, end;
+ phys_addr_t start, end, size;
u64 i;
- /* free reserved array temporarily so that it's treated as free area */
- memblock_free_reserved_regions();
+ for_each_free_mem_range(i, MAX_NUMNODES, &start, &end, NULL)
+ count += __free_memory_core(start, end);
- for_each_free_mem_range(i, MAX_NUMNODES, &start, &end, NULL) {
- unsigned long start_pfn = PFN_UP(start);
- unsigned long end_pfn = min_t(unsigned long,
- PFN_DOWN(end), max_low_pfn);
- if (start_pfn < end_pfn) {
- __free_pages_memory(start_pfn, end_pfn);
- count += end_pfn - start_pfn;
- }
- }
+ /* free range that is used for reserved array if we allocate it */
+ size = get_allocated_memblock_reserved_regions_info(&start);
+ if (size)
+ count += __free_memory_core(start, start + size);
- /* put region array back? */
- memblock_reserve_reserved_regions();
return count;
}