LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: Will Deacon <will.deacon@arm.com>
To: Chintan Pandya <cpandya@codeaurora.org>
Cc: Arnd Bergmann <arnd@arndb.de>,
	Mark Rutland <mark.rutland@arm.com>,
	Ard Biesheuvel <ard.biesheuvel@linaro.org>,
	Marc Zyngier <marc.zyngier@arm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, "H. Peter Anvin" <hpa@zytor.com>,
	Philip Elcan <pelcan@codeaurora.org>,
	James Morse <james.morse@arm.com>,
	Kristina Martsenko <kristina.martsenko@arm.com>,
	Toshi Kani <toshi.kani@hpe.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>,
	Joerg Roedel <joro@8bytes.org>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
Subject: Re: [PATCH v9 3/4] arm64: Implement page table free interfaces
Date: Wed, 23 May 2018 15:01:58 +0100	[thread overview]
Message-ID: <20180523140157.GG26965@arm.com> (raw)
In-Reply-To: <1525074094-25839-4-git-send-email-cpandya@codeaurora.org>

Hi Chintan,

[as a side note: I'm confused on the status of this patch series, as part
 of it was reposted separately by Toshi. Please can you work together?]

On Mon, Apr 30, 2018 at 01:11:33PM +0530, Chintan Pandya wrote:
> Implement pud_free_pmd_page() and pmd_free_pte_page().
> 
> Implementation requires,
>  1) Clearing off the current pud/pmd entry
>  2) Invalidate TLB which could have previously
>     valid but not stale entry
>  3) Freeing of the un-used next level page tables
> 
> Signed-off-by: Chintan Pandya <cpandya@codeaurora.org>
> ---
>  arch/arm64/mm/mmu.c | 29 +++++++++++++++++++++++++----
>  1 file changed, 25 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index da98828..0f651db 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -45,6 +45,7 @@
>  #include <asm/memblock.h>
>  #include <asm/mmu_context.h>
>  #include <asm/ptdump.h>
> +#include <asm/tlbflush.h>
>  
>  #define NO_BLOCK_MAPPINGS	BIT(0)
>  #define NO_CONT_MAPPINGS	BIT(1)
> @@ -973,12 +974,32 @@ int pmd_clear_huge(pmd_t *pmdp)
>  	return 1;
>  }
>  
> -int pud_free_pmd_page(pud_t *pud, unsigned long addr)
> +int pmd_free_pte_page(pmd_t *pmdp, unsigned long addr)
>  {
> -	return pud_none(*pud);
> +	pmd_t *table;
> +
> +	if (pmd_present(READ_ONCE(*pmdp))) {

Might also be worth checking pmd_table here, just in case. (same for pud)

> +		table = __va(pmd_val(*pmdp));

Can you avoid dereferencing *pmdp twice, and instead READ_ONCE into a local
variable, please? (same for pud)

> +		pmd_clear(pmdp);
> +		__flush_tlb_kernel_pgtable(addr);
> +		free_page((unsigned long) table);

Shouldn't this be pte_free_kernel, to pair with pte_alloc_kernel which
was used to allocate the page in the first place? (similarly for pud)

> +	}
> +	return 1;
>  }
>  
> -int pmd_free_pte_page(pmd_t *pmd, unsigned long addr)
> +int pud_free_pmd_page(pud_t *pudp, unsigned long addr)
>  {
> -	return pmd_none(*pmd);
> +	pmd_t *table;
> +	int i;
> +
> +	if (pud_present(READ_ONCE(*pudp))) {
> +		table = __va(pud_val(*pudp));
> +		for (i = 0; i < PTRS_PER_PMD; i++)
> +			pmd_free_pte_page(&table[i], addr + (i * PMD_SIZE));

I think it would be cleaner to write this as a do { ... } while, for
consistency with the ioremap and vmalloc code.

Will

  reply	other threads:[~2018-05-23 14:01 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-30  7:41 [PATCH v9 0/4] Fix issues with huge mapping in ioremap for ARM64 Chintan Pandya
2018-04-30  7:41 ` [PATCH v9 1/4] ioremap: Update pgtable free interfaces with addr Chintan Pandya
2018-04-30  7:41 ` [PATCH v9 2/4] arm64: tlbflush: Introduce __flush_tlb_kernel_pgtable Chintan Pandya
2018-04-30  7:41 ` [PATCH v9 3/4] arm64: Implement page table free interfaces Chintan Pandya
2018-05-23 14:01   ` Will Deacon [this message]
2018-05-23 14:34     ` Kani, Toshi
2018-05-24  7:03       ` Chintan Pandya
2018-05-24  7:34     ` Chintan Pandya
2018-04-30  7:41 ` [PATCH v9 4/4] Revert "arm64: Enforce BBM for huge IO/VMAP mappings" Chintan Pandya

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180523140157.GG26965@arm.com \
    --to=will.deacon@arm.com \
    --cc=akpm@linux-foundation.org \
    --cc=ard.biesheuvel@linaro.org \
    --cc=arnd@arndb.de \
    --cc=cpandya@codeaurora.org \
    --cc=dave.hansen@linux.intel.com \
    --cc=gregkh@linuxfoundation.org \
    --cc=hpa@zytor.com \
    --cc=james.morse@arm.com \
    --cc=joro@8bytes.org \
    --cc=kristina.martsenko@arm.com \
    --cc=linux-arch@vger.kernel.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=marc.zyngier@arm.com \
    --cc=mark.rutland@arm.com \
    --cc=mingo@redhat.com \
    --cc=pelcan@codeaurora.org \
    --cc=tglx@linutronix.de \
    --cc=toshi.kani@hpe.com \
    --cc=vkuznets@redhat.com \
    --subject='Re: [PATCH v9 3/4] arm64: Implement page table free interfaces' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).