Re: [PATCH v2] mm: Track page table modifications in __apply_to_page_range()

From: Pavel Machek
Date: Sat Aug 22 2020 - 17:25:54 EST


Hi!
> > > The __apply_to_page_range() function is also used to change and/or
> > > allocate page-table pages in the vmalloc area of the address space.
> > > Make sure these changes get synchronized to other page-tables in the
> > > system by calling arch_sync_kernel_mappings() when necessary.
> >
> > There's no description here of the user-visible effects of the bug.
> > Please always provide this, especially when proposing a -stable
> > backport. Take pity upon all the downstream kernel maintainers who are
> > staring at this wondering whether they should risk adding it to their
> > kernels.
>
> The impact appears limited to x86-32, where apply_to_page_range may miss
> updating the PMD. That leads to explosions in drivers like

Is this alone supposed to fix my problems with graphics on Thinkpad
X60? Let me try...

Best regards,
Pavel

--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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