Hi Sato-san,
CC Rob , Willy, linux-arch
On Tue, Jul 31, 2018 at 7:15 AM Yoshinori Sato
<ysato@xxxxxxxxxxxxxxxxxxxx> wrote:
> pgd_cache specifies __GFP_ZERO when allocating.
> This constructor is meaningless.
>
> Signed-off-by: Yoshinori Sato <ysato@xxxxxxxxxxxxxxxxxxxx>
Thanks for your patch!
> --- a/arch/sh/mm/pgtable.c
> +++ b/arch/sh/mm/pgtable.c
> @@ -9,20 +9,11 @@ static struct kmem_cache *pgd_cachep;
> static struct kmem_cache *pmd_cachep;
> #endif
>
> -void pgd_ctor(void *x)
> -{
> - pgd_t *pgd = x;
> -
> - memcpy(pgd + USER_PTRS_PER_PGD,
> - swapper_pg_dir + USER_PTRS_PER_PGD,
> - (PTRS_PER_PGD - USER_PTRS_PER_PGD) * sizeof(pgd_t));
> -}
> -
> void pgtable_cache_init(void)
> {
> pgd_cachep = kmem_cache_create("pgd_cache",
> PTRS_PER_PGD * (1<<PTE_MAGNITUDE),
> - PAGE_SIZE, SLAB_PANIC, pgd_ctor);
> + PAGE_SIZE, SLAB_PANIC, NULL);
> #if PAGETABLE_LEVELS > 2
> pmd_cachep = kmem_cache_create("pmd_cache",
> PTRS_PER_PMD * (1<<PTE_MAGNITUDE),
While I can confirm your patch fixes the
WARNING: CPU: 0 PID: 1 at mm/slub.c:2412
___slab_alloc.constprop.34+0x196/0x288
seen since commit 128227e7fe4087b6 ("slab: __GFP_ZERO is incompatible
with a constructor"), I'm not 100% sure this is the correct fix.
swapper_pg_dir[] does have two non-zero entries (768 and 895), which were
copied by the constructor. Perhaps SH does have a need for these two
entries, and thus for the constructor?
Unfortunately I'm too SH-illiterate to answer this myself.
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
