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: Wed, 17 Jul 2019 23:43:43 +0200 (CEST) [thread overview]
Message-ID: <alpine.DEB.2.21.1907172337590.1778@nanos.tec.linutronix.de> (raw)
In-Reply-To: <20190717071439.14261-3-joro@8bytes.org>
On Wed, 17 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.
>
> Fixes: 5d72b4fba40ef ('x86, mm: support huge I/O mapping capability I/F')
> Signed-off-by: Joerg Roedel <jroedel@suse.de>
> ---
> 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);
> +
> + if (!pmd_present(*pmd_k))
> + return NULL;
> else
> BUG_ON(pmd_pfn(*pmd) != pmd_pfn(*pmd_k));
So in case of unmap, this updates only the first entry in the pgd_list
because vmalloc_sync_all() will break out of the iteration over pgd_list
when NULL is returned from vmalloc_sync_one().
I'm surely missing something, but how is that supposed to sync _all_ page
tables on unmap as the changelog claims?
Thanks,
tglx
next prev parent reply other threads:[~2019-07-17 21:43 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-17 7:14 [PATCH 0/3 v2] Sync unmappings in vmalloc/ioremap areas Joerg Roedel
2019-07-17 7:14 ` [PATCH 1/3] x86/mm: Check for pfn instead of page in vmalloc_sync_one() Joerg Roedel
2019-07-17 7:14 ` [PATCH 2/3] x86/mm: Sync also unmappings " Joerg Roedel
2019-07-17 21:06 ` Dave Hansen
2019-07-18 8:44 ` Joerg Roedel
2019-07-17 21:43 ` Thomas Gleixner [this message]
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
2019-07-17 7:14 ` [PATCH 3/3] mm/vmalloc: Sync unmappings in vunmap_page_range() Joerg Roedel
2019-07-17 21:24 ` Andy Lutomirski
2019-07-18 9:17 ` Joerg Roedel
2019-07-18 19:04 ` Andy Lutomirski
2019-07-19 12:21 ` Joerg Roedel
2019-07-19 12:24 ` Andy Lutomirski
2019-07-19 13:00 ` Joerg Roedel
-- strict thread matches above, loose matches on Subject: below --
2019-07-15 11:02 [PATCH 0/3] Sync unmappings in vmalloc/ioremap areas Joerg Roedel
2019-07-15 11:02 ` [PATCH 2/3] x86/mm: Sync also unmappings in vmalloc_sync_one() Joerg Roedel
2019-07-15 13:08 ` Thomas Gleixner
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