mm: do not allocate page->ptl dynamically, if spinlock_t fits to long
In struct page we have enough space to fit long-size page->ptl there, but we use dynamically-allocated page->ptl if size(spinlock_t) is larger than sizeof(int). It hurts 64-bit architectures with CONFIG_GENERIC_LOCKBREAK, where sizeof(spinlock_t) == 8, but it easily fits into struct page. Signed-off-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: NHugh Dickins <hughd@google.com> Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
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