Hello Russell,
(I didn't add you to the recipients of that mail, because your mail had
a Reply-To: header. So I assume that's what you want.)
> > > Removing the calls to dec_zone_page_state() and pte_lock_deinit() in
> > > free_pgd_slow() fixed it for me.
> >
> > That is imho the best way to fix it.
>
> ... but at what cost?
I don't see any costs. Can you please enlighten me?
> > > For a complete fix we might want to change the type of pte?
> >
> > You mean instead of a "struct page *" use a pgtable_t ? Yes, that would
> > be cleaner even if it is the same type.
>
> Would someone mind investigating how the code ended up in this mess in
> the first place, so we can avoid this kind of thing in the future?
>
> It looks like the pte_lock_deinit() appeared in
> 4c21e2f2441dc5fbb957b030333f5a3f2d02dea7.
>
> The dec_zone_page_state() used to be dec_page_state(nr_page_table_pages);
> which then became a dec_zone_page_state() in
> df849a1529c106f7460e51479ca78fe07b07dc8c.
>
> Both changes of those changes on their own look correct.
>
> Ah, is it that someone skipped over ARM when they changed the page table
> freeing code? Yes - 2f569afd9ced9ebec9a6eb3dbf6f83429be0a7b4 has:
If you look at the subject line or the earlier mails in that thread,
that is the exact commit I blamed, too.
So below comes a patch. In my eyes this has to go in before 2.6.25.
Best regards
Uwe
---->8----
Fix freeing of page tables for ARM in free_pgd_slow
Since 2f569af (CONFIG_HIGHPTE vs. sub-page page tables.) pte_free() calls
pte_lock_deinit() and dec_zone_page_state(). So free_pgd_slow must not call
the latter two when calling the first.
Signed-off-by: Uwe Kleine-König <Uwe.Kleine-Koenig@xxxxxxxx>
Cc: Russell King <rmk@xxxxxxxxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
---
arch/arm/mm/pgd.c | 6 ++----
1 files changed, 2 insertions(+), 4 deletions(-)
diff --git a/arch/arm/mm/pgd.c b/arch/arm/mm/pgd.c
index 500c961..e0f19ab 100644
--- a/arch/arm/mm/pgd.c
+++ b/arch/arm/mm/pgd.c
@@ -75,7 +75,7 @@ no_pgd:
void free_pgd_slow(struct mm_struct *mm, pgd_t *pgd)
{
pmd_t *pmd;
- struct page *pte;
+ pgtable_t pte;
if (!pgd)
return;
@@ -90,10 +90,8 @@ void free_pgd_slow(struct mm_struct *mm, pgd_t *pgd)
goto free;
}
- pte = pmd_page(*pmd);
+ pte = pmd_pgtable(*pmd);
pmd_clear(pmd);
- dec_zone_page_state(virt_to_page((unsigned long *)pgd), NR_PAGETABLE);
- pte_lock_deinit(pte);
pte_free(mm, pte);
pmd_free(mm, pmd);
free:
--
1.5.4.3
--
Uwe Kleine-König, Software Engineer
Digi International GmbH Branch Breisach, Küferstrasse 8, 79206 Breisach, Germany
Tax: 315/5781/0242 / VAT: DE153662976 / Reg. Amtsgericht Dortmund HRB 13962
-
To unsubscribe from this list: send the line "unsubscribe linux-arch" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
