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From: Joerg Roedel <jroedel@suse.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>,
	Thomas Gleixner <tglx@linutronix.de>,
	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
Subject: Re: [PATCH 3/3] mm/vmalloc: Sync unmappings in vunmap_page_range()
Date: Mon, 22 Jul 2019 10:11:15 +0200	[thread overview]
Message-ID: <20190722081115.GH19068@suse.de> (raw)
In-Reply-To: <20190719184652.11391-4-joro@8bytes.org>

Srewed up the subject :(, it needs to be

	"mm/vmalloc: Sync unmappings in __purge_vmap_area_lazy()"

of course.

On Fri, Jul 19, 2019 at 08:46:52PM +0200, Joerg Roedel wrote:
> From: Joerg Roedel <jroedel@suse.de>
> 
> On x86-32 with PTI enabled, parts of the kernel page-tables
> are not shared between processes. This can cause mappings in
> the vmalloc/ioremap area to persist in some page-tables
> after the region is unmapped and released.
> 
> When the region is re-used the processes with the old
> mappings do not fault in the new mappings but still access
> the old ones.
> 
> This causes undefined behavior, in reality often data
> corruption, kernel oopses and panics and even spontaneous
> reboots.
> 
> Fix this problem by activly syncing unmaps in the
> vmalloc/ioremap area to all page-tables in the system before
> the regions can be re-used.
> 
> References: https://bugzilla.suse.com/show_bug.cgi?id=1118689
> Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
> Fixes: 5d72b4fba40ef ('x86, mm: support huge I/O mapping capability I/F')
> Signed-off-by: Joerg Roedel <jroedel@suse.de>
> ---
>  mm/vmalloc.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 4fa8d84599b0..e0fc963acc41 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1258,6 +1258,12 @@ static bool __purge_vmap_area_lazy(unsigned long start, unsigned long end)
>  	if (unlikely(valist == NULL))
>  		return false;
>  
> +	/*
> +	 * First make sure the mappings are removed from all page-tables
> +	 * before they are freed.
> +	 */
> +	vmalloc_sync_all();
> +
>  	/*
>  	 * TODO: to calculate a flush range without looping.
>  	 * The list can be up to lazy_max_pages() elements.
> @@ -3038,6 +3044,9 @@ EXPORT_SYMBOL(remap_vmalloc_range);
>  /*
>   * Implement a stub for vmalloc_sync_all() if the architecture chose not to
>   * have one.
> + *
> + * The purpose of this function is to make sure the vmalloc area
> + * mappings are identical in all page-tables in the system.
>   */
>  void __weak vmalloc_sync_all(void)
>  {
> -- 
> 2.17.1

  reply	other threads:[~2019-07-22  8:11 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-19 18:46 [PATCH 0/3 v3] Sync unmappings in vmalloc/ioremap areas Joerg Roedel
2019-07-19 18:46 ` [PATCH 1/3] x86/mm: Check for pfn instead of page in vmalloc_sync_one() Joerg Roedel
2019-07-22  8:22   ` [tip:x86/urgent] " tip-bot for Joerg Roedel
2019-07-19 18:46 ` [PATCH 2/3] x86/mm: Sync also unmappings in vmalloc_sync_all() Joerg Roedel
2019-07-22  8:22   ` [tip:x86/urgent] " tip-bot for Joerg Roedel
2019-07-19 18:46 ` [PATCH 3/3] mm/vmalloc: Sync unmappings in vunmap_page_range() Joerg Roedel
2019-07-22  8:11   ` Joerg Roedel [this message]
2019-07-22  8:19     ` Thomas Gleixner
2019-07-22  8:29       ` Joerg Roedel
2019-07-22  8:23   ` [tip:x86/urgent] mm/vmalloc: Sync unmappings in __purge_vmap_area_lazy() tip-bot for Joerg Roedel
  -- strict thread matches above, loose matches on Subject: below --
2019-07-17  7:14 [PATCH 0/3 v2] Sync unmappings in vmalloc/ioremap areas Joerg Roedel
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
2019-07-15 11:02 [PATCH 0/3] Sync unmappings in vmalloc/ioremap areas Joerg Roedel
2019-07-15 11:02 ` [PATCH 3/3] mm/vmalloc: Sync unmappings in vunmap_page_range() Joerg Roedel

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