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mm, page_alloc: don't duplicate code in free_pcp_prepare 

The new free_pcp_prepare() function shares a lot of code with
free_pages_prepare(), which makes this a maintenance risk when some
future patch modifies only one of them.  We should be able to achieve
the same effect (skipping free_pages_check() from !DEBUG_VM configs) by
adding a parameter to free_pages_prepare() and making it inline, so the
checks (and the order != 0 parts) are eliminated from the call from
free_pcp_prepare().

!DEBUG_VM: bloat-o-meter reports no difference, as my gcc was already
inlining free_pages_prepare() and the elimination seems to work as
expected

DEBUG_VM bloat-o-meter:

  add/remove: 0/1 grow/shrink: 2/0 up/down: 1035/-778 (257)
  function                                     old     new   delta
  __free_pages_ok                              297    1060    +763
  free_hot_cold_page                           480     752    +272
  free_pages_prepare                           778       -    -778

Here inlining didn't occur before, and added some code, but it's ok for
a debug option.

[akpm@linux-foundation.org: fix build]
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mel Gorman 2016-05-19 17:14:38 -07:00 committed by Linus Torvalds
parent 479f854a20
commit e2769dbdc5
1 changed files with 57 additions and 80 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

137
mm/page_alloc.c
View File

@ -991,12 +991,65 @@ static int free_tail_pages_check(struct page *head_page, struct page *page)
return ret;
}
static bool free_pages_prepare(struct page *page, unsigned int order);
static __always_inline bool free_pages_prepare(struct page *page,
unsigned int order, bool check_free)
{
int bad = 0;
VM_BUG_ON_PAGE(PageTail(page), page);
trace_mm_page_free(page, order);
kmemcheck_free_shadow(page, order);
kasan_free_pages(page, order);
/*
* Check tail pages before head page information is cleared to
* avoid checking PageCompound for order-0 pages.
*/
if (unlikely(order)) {
bool compound = PageCompound(page);
int i;
VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
for (i = 1; i < (1 << order); i++) {
if (compound)
bad += free_tail_pages_check(page, page + i);
if (unlikely(free_pages_check(page + i))) {
bad++;
continue;
}
(page + i)->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
}
}
if (PageAnonHead(page))
page->mapping = NULL;
if (check_free)
bad += free_pages_check(page);
if (bad)
return false;
page_cpupid_reset_last(page);
page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
reset_page_owner(page, order);
if (!PageHighMem(page)) {
debug_check_no_locks_freed(page_address(page),
PAGE_SIZE << order);
debug_check_no_obj_freed(page_address(page),
PAGE_SIZE << order);
}
arch_free_page(page, order);
kernel_poison_pages(page, 1 << order, 0);
kernel_map_pages(page, 1 << order, 0);
return true;
}
#ifdef CONFIG_DEBUG_VM
static inline bool free_pcp_prepare(struct page *page)
{
return free_pages_prepare(page, 0);
return free_pages_prepare(page, 0, true);
}
static inline bool bulkfree_pcp_prepare(struct page *page)
@ -1006,30 +1059,7 @@ static inline bool bulkfree_pcp_prepare(struct page *page)
#else
static bool free_pcp_prepare(struct page *page)
{
VM_BUG_ON_PAGE(PageTail(page), page);
trace_mm_page_free(page, 0);
kmemcheck_free_shadow(page, 0);
kasan_free_pages(page, 0);
if (PageAnonHead(page))
page->mapping = NULL;
reset_page_owner(page, 0);
if (!PageHighMem(page)) {
debug_check_no_locks_freed(page_address(page),
PAGE_SIZE);
debug_check_no_obj_freed(page_address(page),
PAGE_SIZE);
}
arch_free_page(page, 0);
kernel_poison_pages(page, 0, 0);
kernel_map_pages(page, 0, 0);
page_cpupid_reset_last(page);
page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
return true;
return free_pages_prepare(page, 0, false);
}
static bool bulkfree_pcp_prepare(struct page *page)
@ -1201,66 +1231,13 @@ void __meminit reserve_bootmem_region(unsigned long start, unsigned long end)
}
}
static bool free_pages_prepare(struct page *page, unsigned int order)
{
int bad = 0;
VM_BUG_ON_PAGE(PageTail(page), page);
trace_mm_page_free(page, order);
kmemcheck_free_shadow(page, order);
kasan_free_pages(page, order);
/*
* Check tail pages before head page information is cleared to
* avoid checking PageCompound for order-0 pages.
*/
if (unlikely(order)) {
bool compound = PageCompound(page);
int i;
VM_BUG_ON_PAGE(compound && compound_order(page) != order, page);
for (i = 1; i < (1 << order); i++) {
if (compound)
bad += free_tail_pages_check(page, page + i);
if (unlikely(free_pages_check(page + i))) {
bad++;
continue;
}
(page + i)->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
}
}
if (PageAnonHead(page))
page->mapping = NULL;
bad += free_pages_check(page);
if (bad)
return false;
page_cpupid_reset_last(page);
page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
reset_page_owner(page, order);
if (!PageHighMem(page)) {
debug_check_no_locks_freed(page_address(page),
PAGE_SIZE << order);
debug_check_no_obj_freed(page_address(page),
PAGE_SIZE << order);
}
arch_free_page(page, order);
kernel_poison_pages(page, 1 << order, 0);
kernel_map_pages(page, 1 << order, 0);
return true;
}
static void __free_pages_ok(struct page *page, unsigned int order)
{
unsigned long flags;
int migratetype;
unsigned long pfn = page_to_pfn(page);
if (!free_pages_prepare(page, order))
if (!free_pages_prepare(page, order, true))
return;
migratetype = get_pfnblock_migratetype(page, pfn);