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SubjectRe: quicklists confuse meminfo

* Ingo Molnar <mingo@elte.hu> wrote:

> > careful with this; the quicklists aren't JUST for speed they are
> > also there to make sure a page we free that is a pagetable, is not
> > reused until we have finished flushing the tlbs on all the cpus that
> > saw it. This is a really hard correctness requirement, and while I
> > can see that quicklists are probably not the best way to achieve
> > this, we can't just throw away the behavior ;(
>
> no, that's not true anymore - and the current quicklists code doesnt
> do anything like that AFAICS. It used to be a lot more complex, but
> now it's just a thin wrapper around the page allocator.

i.e. the patch below should do the trick.

(it's still work in progress but it seems to boot just fine)

Ingo

------------>
Subject: x86: patches/remove-quicklists.patch
From: Ingo Molnar <mingo@elte.hu>
Date: Sun Mar 09 20:04:32 CET 2008

---
arch/x86/mm/pgtable_32.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)

Index: linux-x86.q/arch/x86/mm/pgtable_32.c
===================================================================
--- linux-x86.q.orig/arch/x86/mm/pgtable_32.c
+++ linux-x86.q/arch/x86/mm/pgtable_32.c
@@ -10,7 +10,6 @@
#include <linux/pagemap.h>
#include <linux/spinlock.h>
#include <linux/module.h>
-#include <linux/quicklist.h>

#include <asm/system.h>
#include <asm/pgtable.h>
@@ -338,12 +337,16 @@ static void pgd_mop_up_pmds(struct mm_st

pgd_t *pgd_alloc(struct mm_struct *mm)
{
- pgd_t *pgd = quicklist_alloc(0, GFP_KERNEL, pgd_ctor);
+ pgd_t *pgd;
+
+ pgd = (void *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
+ if (pgd)
+ pgd_ctor(pgd);

mm->pgd = pgd; /* so that alloc_pd can use it */

if (pgd && !pgd_prepopulate_pmd(mm, pgd)) {
- quicklist_free(0, pgd_dtor, pgd);
+ free_page((unsigned long)pgd);
pgd = NULL;
}

@@ -353,12 +356,12 @@ pgd_t *pgd_alloc(struct mm_struct *mm)
void pgd_free(struct mm_struct *mm, pgd_t *pgd)
{
pgd_mop_up_pmds(mm, pgd);
- quicklist_free(0, pgd_dtor, pgd);
+ pgd_dtor(pgd);
+ free_page((unsigned long)pgd);
}

void check_pgt_cache(void)
{
- quicklist_trim(0, pgd_dtor, 25, 16);
}

void __pte_free_tlb(struct mmu_gather *tlb, struct page *pte)

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