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From: Thomas Gleixner <tglx@linutronix.de>
To: Joerg Roedel <joro@8bytes.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
	Andy Lutomirski <luto@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	Joerg Roedel <jroedel@suse.de>
Subject: Re: [PATCH 2/3] x86/mm: Sync also unmappings in vmalloc_sync_one()
Date: Mon, 15 Jul 2019 15:08:14 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.21.1907151504190.1722@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20190715110212.18617-3-joro@8bytes.org>

On Mon, 15 Jul 2019, Joerg Roedel wrote:

> From: Joerg Roedel <jroedel@suse.de>
> 
> With huge-page ioremap areas the unmappings also need to be
> synced between all page-tables. Otherwise it can cause data
> corruption when a region is unmapped and later re-used.
> 
> Make the vmalloc_sync_one() function ready to sync
> unmappings.
> 
> Signed-off-by: Joerg Roedel <jroedel@suse.de>

Lacks a Fixes tag methinks.

> ---
>  arch/x86/mm/fault.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
> index 4a4049f6d458..d71e167662c3 100644
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -194,11 +194,12 @@ static inline pmd_t *vmalloc_sync_one(pgd_t *pgd, unsigned long address)
>  
>  	pmd = pmd_offset(pud, address);
>  	pmd_k = pmd_offset(pud_k, address);
> -	if (!pmd_present(*pmd_k))
> -		return NULL;
>  
> -	if (!pmd_present(*pmd))
> +	if (pmd_present(*pmd) ^ pmd_present(*pmd_k))
>  		set_pmd(pmd, *pmd_k);

It took me a while to understand what this is doing. Can we please have a
comment here?

> +
> +	if (!pmd_present(*pmd_k))
> +		return NULL;

Thanks,

	tglx

  reply	other threads:[~2019-07-15 13:08 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-15 11:02 [PATCH 0/3] Sync unmappings in vmalloc/ioremap areas Joerg Roedel
2019-07-15 11:02 ` [PATCH 1/3] x86/mm: Check for pfn instead of page in vmalloc_sync_one() Joerg Roedel
2019-07-15 13:08   ` Thomas Gleixner
2019-07-15 15:44     ` Joerg Roedel
2019-07-15 18:48       ` Thomas Gleixner
2019-07-15 11:02 ` [PATCH 2/3] x86/mm: Sync also unmappings " Joerg Roedel
2019-07-15 13:08   ` Thomas Gleixner [this message]
2019-07-15 11:02 ` [PATCH 3/3] mm/vmalloc: Sync unmappings in vunmap_page_range() Joerg Roedel
2019-07-17  7:14 [PATCH 0/3 v2] Sync unmappings in vmalloc/ioremap areas Joerg Roedel
2019-07-17  7:14 ` [PATCH 2/3] x86/mm: Sync also unmappings in vmalloc_sync_one() Joerg Roedel
2019-07-17 21:06   ` Dave Hansen
2019-07-18  8:44     ` Joerg Roedel
2019-07-17 21:43   ` Thomas Gleixner
2019-07-18  8:46     ` Joerg Roedel
2019-07-18  9:04       ` Thomas Gleixner
2019-07-18  9:25         ` Joerg Roedel
2019-07-19 14:01         ` Joerg Roedel
2019-07-19 21:10           ` Thomas Gleixner

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