Re: [PATCH STABLE 4.9] x86, mm, gup: prevent get_page() race with munmap in paravirt guest

[Ben Hutchings]

On Mon, 2019-08-19 at 18:58 +0100, Vlastimil Babka wrote:
[...]
> Hi, I'm sending this stable-only patch for consideration because it's probably
> unrealistic to backport the 4.13 switch to generic GUP. I can look at 4.4 and
> 3.16 if accepted. The RCU page table freeing could be also considered.

I would be interested in backports for 3.16 and 4.4.

> Note the patch also includes page refcount protection. I found out that
> 8fde12ca79af ("mm: prevent get_user_pages() from overflowing page refcount")
> backport to 4.9 missed the arch-specific gup implementations:
> https://lore.kernel.org/lkml/6650323f-dbc9-f069-000b-f6b0f941a065@xxxxxxx/
[...]

I suppose that still needs to be addressed for 4.9, right?

Ben.

-- 
Ben Hutchings
Quantity is no substitute for quality, but it's the only one we've got.

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