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SubjectRe: [PATCH 1/3] x86/mm: Check for pfn instead of page in vmalloc_sync_one()
On Mon, Jul 15, 2019 at 03:08:42PM +0200, Thomas Gleixner wrote:
> On Mon, 15 Jul 2019, Joerg Roedel wrote:
> > From: Joerg Roedel <>
> >
> > Do not require a struct page for the mapped memory location
> > because it might not exist. This can happen when an
> > ioremapped region is mapped with 2MB pages.
> >
> > Signed-off-by: Joerg Roedel <>
> Lacks a Fixes tag, hmm?

Yeah, right, the question is, which commit to put in there. The problem
results from two changes:

1) Introduction of !SHARED_KERNEL_PMD path in x86-32. In itself
this is not a problem, and the path was only enabled for

2) Huge IORemapings which use the PMD level. Also not a problem
by itself, but together with !SHARED_KERNEL_PMD problematic
because it requires to sync the PMD entries between all
page-tables, and that was not implemented.

Before PTI-x32 was merged this problem did not show up, maybe because
the 32-bit Xen-PV users did not trigger it. But with PTI-x32 all PAE
users run with !SHARED_KERNEL_PMD and the problem popped up.

For the last patch I put the PTI-x32 enablement commit in the fixes tag,
because that was the one that showed up during bisection. But more
correct would probably be

5d72b4fba40e ('x86, mm: support huge I/O mapping capability I/F')

Or do I miss something?



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