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mm: always inline _compound_head() with CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP=y

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We already force-inline page_fixed_fake_head(), page_is_fake_head() and
PageTail(), however the compiler might decide that _compound_head() is not
worthy to be inlined, because of page_fixed_fake_head().

The result is that, for example, PageAnonExclusive() now might involve a
function call when checking PageHuge(), which performs a
page_folio()->_compound_head() call.  This can lead to a slight regression
of the stress-ng.clone benchmark.

This is not super-urgent to fix, but always inlining _compound_head()
seems like the obvious thing to do for this primitive, similar to the
other ones.

This change restores the slight regression and a compilation with
CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP=y shows no relevant bloat [2]:

	add/remove: 15/14 grow/shrink: 79/87 up/down: 12836/-13917 (-1081)
	...
	Total: Before=32786363, After=32785282, chg -0.00%

[1] https://lkml.kernel.org/r/817150f2-abf7-430f-9973-540bd6cdd26f@intel.com
[2] https://lore.kernel.org/all/116e117c-2821-401d-8e62-b85cdec37f4a@redhat.com/

Link: https://lkml.kernel.org/r/20240820122210.660140-1-david@redhat.com
Fixes: c0bff412e6 ("mm: allow anon exclusive check over hugetlb tail pages")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202407301049.5051dc19-oliver.sang@intel.com
Tested-by: Yin Fengwei <fengwei.yin@intel.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Hildenbrand 2024-08-20 14:22:10 +02:00 committed by Andrew Morton
parent 8c86859289
commit ef5f379de3
1 changed files with 1 additions and 1 deletions
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2
include/linux/page-flags.h
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@ -232,7 +232,7 @@ static __always_inline int page_is_fake_head(const struct page *page)
return page_fixed_fake_head(page) != page; return page_fixed_fake_head(page) != page;
} }
static inline unsigned long _compound_head(const struct page *page) static __always_inline unsigned long _compound_head(const struct page *page)
{ {
unsigned long head = READ_ONCE(page->compound_head); unsigned long head = READ_ONCE(page->compound_head);