Andrew Morton wrote: > On Fri, 27 Sep 2013 16:16:26 +0300 "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx> wrote: > > > The basic idea is the same as with PTE level: the lock is embedded into > > struct page of table's page. > > > > We can't use mm->pmd_huge_pte to store pgtables for THP, since we don't > > take mm->page_table_lock anymore. Let's reuse page->lru of table's page > > for that. > > > > pgtable_pmd_page_ctor() returns true, if initialization is successful > > and false otherwise. Current implementation never fails, but assumption > > that constructor can fail will help to port it to -rt where spinlock_t > > is rather huge and cannot be embedded into struct page -- dynamic > > allocation is required. > > spinlock_t is rather large when lockdep is enabled. What happens? The same as with PTE split lock: CONFIG_SPLIT_PTLOCK_CPUS set to 999999 if DEBUG_SPINLOCK || DEBUG_LOCK_ALLOC. It effectively blocks split locks usage if spinlock_t is too big. -- Kirill A. Shutemov -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>