Re: [PATCH] sh: remove unneeded constructor.
From: Geert Uytterhoeven <geert@linux-m68k.org>
Date: 2018-08-01 09:26:36
Also in:
linux-sh
Hi Sato-san, CC Rob , Willy, linux-arch On Tue, Jul 31, 2018 at 7:15 AM Yoshinori Sato [off-list ref] wrote:
pgd_cache specifies __GFP_ZERO when allocating. This constructor is meaningless. Signed-off-by: Yoshinori Sato <ysato@users.sourceforge.jp>
Thanks for your patch!
quoted hunk
--- 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@linux-m68k.org
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