Re: [PATCH] mm/vmalloc: Fix regression caused by needless vmalloc_sync_all()

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On Thu, 14 Nov 2019 18:12:31 +0100 Joerg Roedel <jroedel@xxxxxxx> wrote:

> On Wed, Nov 13, 2019 at 05:55:30PM +0800, Shile Zhang wrote:
> > +#if defined(CONFIG_X86_32) && defined(CONFIG_X86_PAE)
> >  	/*
> >  	 * First make sure the mappings are removed from all page-tables
> >  	 * before they are freed.
> > +	 *
> > +	 * This is only needed on x86-32 with !SHARED_KERNEL_PMD, which is
> > +	 * the case on a PAE kernel with PTI enabled.
> >  	 */
> > -	vmalloc_sync_all();
> > +	if (!SHARED_KERNEL_PMD && boot_cpu_has(X86_FEATURE_PTI))
> > +		vmalloc_sync_all();
> > +#endif
> 
> I already submitted another fix for this quite some time ago:
> 
> 	https://lore.kernel.org/lkml/20191009124418.8286-1-joro@xxxxxxxxxx/
> 

Your patch is more verbose but looks quite a bit nicer than this patch
(Link:
http://lkml.kernel.org/r/20191113095530.228959-1-shile.zhang@xxxxxxxxxxxxxxxxx).
The separation of sync-for-a-mapping versus sync-for-an-unmapping adds
clarity.


It's fairly urgent - I consider this to be -stable material.

Thomas & co, was that a deliberate skip?





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