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Date: Sat, 16 Apr 2011 10:44:56 +0100 From: Matt Fleming <matt@...sole-pimps.org> To: Dave Hansen <dave@...ux.vnet.ibm.com> Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org Subject: Re: [RFC][PATCH 2/3] track numbers of pagetable pages On Fri, 15 Apr 2011 10:38:23 -0700 Dave Hansen <dave@...ux.vnet.ibm.com> wrote: > > Now that we have the mm in the constructor and destructor, it's > simple to to bump a counter. Add the counter to the mm and use > the existing MM_* counter infrastructure. > > Signed-off-by: Dave Hansen <dave@...ux.vnet.ibm.com> > --- > > linux-2.6.git-dave/include/linux/mm.h | 2 ++ > linux-2.6.git-dave/include/linux/mm_types.h | 1 + > 2 files changed, 3 insertions(+) > > diff -puN include/linux/mm.h~track-pagetable-pages include/linux/mm.h > --- linux-2.6.git/include/linux/mm.h~track-pagetable-pages 2011-04-15 10:37:10.768832396 -0700 > +++ linux-2.6.git-dave/include/linux/mm.h 2011-04-15 10:37:10.780832393 -0700 > @@ -1245,12 +1245,14 @@ static inline pmd_t *pmd_alloc(struct mm > static inline void pgtable_page_ctor(struct mm_struct *mm, struct page *page) > { > pte_lock_init(page); > + inc_mm_counter(mm, MM_PTEPAGES); > inc_zone_page_state(page, NR_PAGETABLE); > } > > static inline void pgtable_page_dtor(struct mm_struct *mm, struct page *page) > { > pte_lock_deinit(page); > + dec_mm_counter(mm, MM_PTEPAGES); > dec_zone_page_state(page, NR_PAGETABLE); > } I'm probably missing something really obvious but... Is this safe in the non-USE_SPLIT_PTLOCKS case? If we're not using split-ptlocks then inc/dec_mm_counter() are only safe when done under mm->page_table_lock, right? But it looks to me like we can end up doing, __pte_alloc() pte_alloc_one() pgtable_page_ctor() before acquiring mm->page_table_lock in __pte_alloc(). -- Matt Fleming, Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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