From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Will Deacon <will.deacon@arm.com>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Nicholas Piggin <npiggin@gmail.com>,
Linux-Arch <linux-arch@vger.kernel.org>,
Linux MM <linux-mm@kvack.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Russell King <linux@armlinux.org.uk>,
Heiko Carstens <heiko.carstens@de.ibm.com>,
Rik van Riel <riel@surriel.com>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Rich Felker <dalias@libc.org>,
Linux-sh list <linux-sh@vger.kernel.org>,
Guenter Roeck <linux@roeck-us.net>
Subject: Re: [PATCH v6 10/18] sh/tlb: Convert SH to generic mmu_gather
Date: Thu, 5 Dec 2019 16:26:57 +0100 [thread overview]
Message-ID: <CAMuHMdVQO6vMDuns7rwk8sD+cPhEVQjEU_DiKiTQn0NY2ppzag@mail.gmail.com> (raw)
In-Reply-To: <20191204164143.GB2810@hirez.programming.kicks-ass.net>
Hoi Peter,
On Wed, Dec 4, 2019 at 5:42 PM Peter Zijlstra <peterz@infradead.org> wrote:
> On Wed, Dec 04, 2019 at 04:07:53PM +0100, Geert Uytterhoeven wrote:
> > On Wed, Dec 4, 2019 at 2:35 PM Peter Zijlstra <peterz@infradead.org> wrote:
> > > Does this fare better?
> >
> > Yes. Migo-R is happy again.
> > Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
> >
> > > --- a/arch/sh/include/asm/pgalloc.h
> > > +++ b/arch/sh/include/asm/pgalloc.h
> > > @@ -36,9 +36,7 @@ do { \
> > > #if CONFIG_PGTABLE_LEVELS > 2
> > > #define __pmd_free_tlb(tlb, pmdp, addr) \
> > > do { \
> > > - struct page *page = virt_to_page(pmdp); \
> > > - pgtable_pmd_page_dtor(page); \
> > > - tlb_remove_page((tlb), page); \
> > > + pmd_free((tlb)->mm, (pmdp)); \
> > > } while (0);
> > > #endif
>
> OK, so I was going to write a Changelog to go with that, but then I
> realized that while this works and is similar to before the patch, I'm
> not sure this is in fact correct.
>
> With this on (and also before) we're freeing the PMD before we've done
> the TLB invalidate, that seems wrong!
>
> Looking at the size of that pmd_cache, that looks to be 30-(12+12-3)+3
> == 12, which is exactly 1 page, for PAGE_SIZE_4K, less for the larger
> pages.
>
> I'm thinking perhaps we should do something like the below instead?
Your advice is better when in close vicinity of an SH cross compiler,
though ;-)
> --- a/arch/sh/mm/pgtable.c
> +++ b/arch/sh/mm/pgtable.c
> @@ -5,9 +5,6 @@
> #define PGALLOC_GFP GFP_KERNEL | __GFP_ZERO
>
> static struct kmem_cache *pgd_cachep;
> -#if PAGETABLE_LEVELS > 2
> -static struct kmem_cache *pmd_cachep;
> -#endif
>
> void pgd_ctor(void *x)
> {
> @@ -23,11 +20,6 @@ void pgtable_cache_init(void)
> pgd_cachep = kmem_cache_create("pgd_cache",
> PTRS_PER_PGD * (1<<PTE_MAGNITUDE),
> PAGE_SIZE, SLAB_PANIC, pgd_ctor);
> -#if PAGETABLE_LEVELS > 2
> - pmd_cachep = kmem_cache_create("pmd_cache",
> - PTRS_PER_PMD * (1<<PTE_MAGNITUDE),
> - PAGE_SIZE, SLAB_PANIC, NULL);
> -#endif
> }
>
> pgd_t *pgd_alloc(struct mm_struct *mm)
> @@ -48,11 +40,7 @@ void pud_populate(struct mm_struct *mm, pud_t *pud, pmd_t *pmd)
>
> pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
> {
> - return kmem_cache_alloc(pmd_cachep, PGALLOC_GFP);
> -}
> -
> -void pmd_free(struct mm_struct *mm, pmd_t *pmd)
mm/memory.o: In function `__pmd_alloc':
memory.c:(.text+0x1d74): undefined reference to `pmd_free'
> -{
> - kmem_cache_free(pmd_cachep, pmd);
> + BUILD_BUG_ON(PTRS_PER_PMD * (1<<PTE_MAGNITUDE) <= PAGE_SIZE);
... > PAGE_SIZE ?
Else it triggers all the time.
> + return (pmd_t *)__get_free_page(PGALLOC_GFP);
> }
> #endif /* PAGETABLE_LEVELS > 2 */
BTW, I'm still running Willy's fix that never made it upstream
to kill an ugly boot warning, which also touches this code:
https://patchwork.kernel.org/patch/10549883/#22166333
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
next prev parent reply other threads:[~2019-12-05 15:27 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-19 10:31 [PATCH v6 00/18] generic mmu_gather patches Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 01/18] asm-generic/tlb: Provide a comment Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 02/18] asm-generic/tlb: Provide HAVE_MMU_GATHER_PAGE_SIZE Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 03/18] asm-generic/tlb: Provide generic VIPT cache flush Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 04/18] asm-generic/tlb: Provide generic tlb_flush() based on flush_tlb_range() Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 05/18] asm-generic/tlb: Provide generic tlb_flush() based on flush_tlb_mm() Peter Zijlstra
2019-02-19 12:47 ` Will Deacon
2019-02-19 10:31 ` [PATCH v6 06/18] asm-generic/tlb: Conditionally provide tlb_migrate_finish() Peter Zijlstra
2019-02-19 12:47 ` Will Deacon
2019-02-19 13:41 ` Peter Zijlstra
2019-02-20 14:47 ` Will Deacon
2019-02-20 15:02 ` Matthew Wilcox
2019-02-19 10:31 ` [PATCH v6 07/18] asm-generic/tlb: Invert HAVE_RCU_TABLE_INVALIDATE Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 08/18] arm/tlb: Convert to generic mmu_gather Peter Zijlstra
2019-02-19 10:31 ` [PATCH v6 09/18] ia64/tlb: Conver " Peter Zijlstra
2019-02-19 12:47 ` Will Deacon
2019-02-21 2:52 ` Souptick Joarder
2019-02-19 10:31 ` [PATCH v6 10/18] sh/tlb: Convert SH " Peter Zijlstra
2019-12-03 11:19 ` Geert Uytterhoeven
2019-12-04 10:47 ` Peter Zijlstra
2019-12-04 12:32 ` Geert Uytterhoeven
2019-12-04 13:22 ` Guenter Roeck
2019-12-04 15:17 ` Geert Uytterhoeven
2019-12-04 19:03 ` Guenter Roeck
2019-12-04 13:34 ` Peter Zijlstra
2019-12-04 15:07 ` Geert Uytterhoeven
2019-12-04 16:41 ` Peter Zijlstra
2019-12-05 15:26 ` Geert Uytterhoeven [this message]
2020-07-15 19:45 ` John Paul Adrian Glaubitz
2019-12-05 19:24 ` Rob Landley
2019-12-05 19:23 ` Rich Felker
2020-07-15 19:49 ` John Paul Adrian Glaubitz
2019-12-05 19:30 ` John Paul Adrian Glaubitz
2019-12-05 22:56 ` Guenter Roeck
2019-12-06 13:38 ` John Paul Adrian Glaubitz
2019-12-06 14:03 ` Guenter Roeck
2019-02-19 10:31 ` [PATCH v6 11/18] um/tlb: Convert " Peter Zijlstra
2019-02-19 10:32 ` [PATCH v6 12/18] arch/tlb: Clean up simple architectures Peter Zijlstra
2019-02-19 10:32 ` [PATCH v6 13/18] asm-generic/tlb: Introduce HAVE_MMU_GATHER_NO_GATHER Peter Zijlstra
2019-02-19 12:47 ` Will Deacon
2019-02-19 10:32 ` [PATCH v6 14/18] s390/tlb: convert to generic mmu_gather Peter Zijlstra
2019-02-19 12:47 ` Will Deacon
2019-02-19 10:32 ` [PATCH v6 15/18] asm-generic/tlb: Remove arch_tlb*_mmu() Peter Zijlstra
2019-02-19 10:32 ` [PATCH v6 16/18] asm-generic/tlb: Remove HAVE_GENERIC_MMU_GATHER Peter Zijlstra
2019-02-19 10:32 ` [PATCH v6 17/18] asm-generic/tlb: Remove tlb_flush_mmu_free() Peter Zijlstra
2019-02-19 10:32 ` [PATCH v6 18/18] asm-generic/tlb: Remove tlb_table_flush() Peter Zijlstra
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