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mm: dynamically allocate page->ptl if it cannot be embedded to struct page

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If split page table lock is in use, we embed the lock into struct page
of table's page.  We have to disable split lock, if spinlock_t is too
big be to be embedded, like when DEBUG_SPINLOCK or DEBUG_LOCK_ALLOC
enabled.

This patch add support for dynamic allocation of split page table lock
if we can't embed it to struct page.

page->ptl is unsigned long now and we use it as spinlock_t if
sizeof(spinlock_t) <= sizeof(long), otherwise it's pointer to spinlock_t.

The spinlock_t allocated in pgtable_page_ctor() for PTE table and in
pgtable_pmd_page_ctor() for PMD table.  All other helpers converted to
support dynamically allocated page->ptl.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov
2013-11-14 14:31:51 -08:00
committed by Linus Torvalds
parent f820e2805c
commit 49076ec2cc
6 changed files with 179 additions and 24 deletions
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19
mm/memory.c
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@@ -4270,3 +4270,22 @@ 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)
{
spinlock_t *ptl;
ptl = kmalloc(sizeof(spinlock_t), GFP_KERNEL);
if (!ptl)
return false;
page->ptl = (unsigned long)ptl;
return true;
}
void __ptlock_free(struct page *page)
{
if (sizeof(spinlock_t) > sizeof(page->ptl))
kfree((spinlock_t *)page->ptl);
}
#endif