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Commit 539edb58 authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Linus Torvalds
Browse files

mm: properly separate the bloated ptl from the regular case 



Use kernel/bounds.c to convert build-time spinlock_t size check into a
preprocessor symbol and apply that to properly separate the page::ptl
situation.

Signed-off-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 49076ec2

include/linux/mm.h

+13 −11
Original line number Diff line number Diff line
@@ -1317,27 +1317,29 @@ static inline pmd_t *pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long a 
#endif /* CONFIG_MMU && !__ARCH_HAS_4LEVEL_HACK */



#if USE_SPLIT_PTE_PTLOCKS

bool __ptlock_alloc(struct page *page);

void __ptlock_free(struct page *page);

#if BLOATED_SPINLOCKS

extern bool ptlock_alloc(struct page *page);

extern void ptlock_free(struct page *page);



static inline spinlock_t *ptlock_ptr(struct page *page)

{

	return page->ptl;

}

#else /* BLOATED_SPINLOCKS */

static inline bool ptlock_alloc(struct page *page)

{

	if (sizeof(spinlock_t) > sizeof(page->ptl))

		return __ptlock_alloc(page);

	return true;

}



static inline void ptlock_free(struct page *page)

{

	if (sizeof(spinlock_t) > sizeof(page->ptl))

		__ptlock_free(page);

}



static inline spinlock_t *ptlock_ptr(struct page *page)

{

	if (sizeof(spinlock_t) > sizeof(page->ptl))

		return (spinlock_t *) page->ptl;

	else

		return (spinlock_t *) &page->ptl;

	return &page->ptl;

}

#endif /* BLOATED_SPINLOCKS */



static inline spinlock_t *pte_lockptr(struct mm_struct *mm, pmd_t *pmd)

{
@@ -1354,7 +1356,7 @@ static inline bool ptlock_init(struct page *page) 
	 * slab code uses page->slab_cache and page->first_page (for tail

	 * pages), which share storage with page->ptl.

	 */

	VM_BUG_ON(page->ptl);

	VM_BUG_ON(*(unsigned long *)&page->ptl);

	if (!ptlock_alloc(page))

		return false;

	spin_lock_init(ptlock_ptr(page));

include/linux/mm_types.h

+5 −4
Original line number Diff line number Diff line
@@ -147,10 +147,11 @@ struct page { 
						 * system if PG_buddy is set.

						 */

#if USE_SPLIT_PTE_PTLOCKS

		unsigned long ptl; /* It's spinlock_t if it fits to long,

				    * otherwise it's pointer to dynamicaly

				    * allocated spinlock_t.

				    */

#if BLOATED_SPINLOCKS

		spinlock_t *ptl;

#else

		spinlock_t ptl;

#endif

#endif

		struct kmem_cache *slab_cache;	/* SL[AU]B: Pointer to slab */

		struct page *first_page;	/* Compound tail pages */

kernel/bounds.c

+2 −0
Original line number Diff line number Diff line
@@ -11,6 +11,7 @@ 
#include <linux/kbuild.h>

#include <linux/page_cgroup.h>

#include <linux/log2.h>

#include <linux/spinlock.h>



void foo(void)

{
@@ -21,5 +22,6 @@ void foo(void) 
#ifdef CONFIG_SMP

	DEFINE(NR_CPUS_BITS, ilog2(CONFIG_NR_CPUS));

#endif

	DEFINE(BLOATED_SPINLOCKS, sizeof(spinlock_t) > sizeof(int));

	/* End of constants */

}

mm/memory.c

+5 −6
Original line number Diff line number Diff line
@@ -4271,21 +4271,20 @@ void copy_user_huge_page(struct page *dst, struct page *src, 
}

#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */



#if USE_SPLIT_PTE_PTLOCKS

bool __ptlock_alloc(struct page *page)

#if USE_SPLIT_PTE_PTLOCKS && BLOATED_SPINLOCKS

bool ptlock_alloc(struct page *page)

{

	spinlock_t *ptl;



	ptl = kmalloc(sizeof(spinlock_t), GFP_KERNEL);

	if (!ptl)

		return false;

	page->ptl = (unsigned long)ptl;

	page->ptl = ptl;

	return true;

}



void __ptlock_free(struct page *page)

void ptlock_free(struct page *page)

{

	if (sizeof(spinlock_t) > sizeof(page->ptl))

		kfree((spinlock_t *)page->ptl);

	kfree(page->ptl);

}

#endif