RE: LTP regressions due to 6dc296e7df4c ("mm: make sure all file VMAs have ->vm_ops set")

From: Kirill A. Shutemov
Date: Mon Sep 14 2015 - 07:58:09 EST

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Will Deacon wrote:
> Hi Kirill,
>
> Your patch 6dc296e7df4c ("mm: make sure all file VMAs have ->vm_ops set")
> causes some mmap regressions in LTP, which appears to use a MAP_PRIVATE
> mmap of /dev/zero as a way to get anonymous pages in some of its tests
> (specifically mmap10 [1]).
>
> Dead simple reproducer below. Is this change in behaviour intentional?

Ouch. Of couse it's a bug.

Fix is below. I don't really like it, but I cannot find any better
solution.

Next message: Meelis Roos: "Unable to handle kernel NULL pointer dereference at 000000f0, in arch_dma_alloc_attrs+0x5/0x80"
Previous message: SF Markus Elfring: "Re: [PATCH 00/39] drop null test before destroy functions"
In reply to: Will Deacon: "LTP regressions due to 6dc296e7df4c ("mm: make sure all file VMAs have ->vm_ops set")"
Next in thread: Will Deacon: "Re: LTP regressions due to 6dc296e7df4c ("mm: make sure all file VMAs have ->vm_ops set")"
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