Re: Test case for "mm/thp: carry over dirty bit when thp splits on pmd"

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On 16.11.22 11:45, Anatoly Pugachev wrote:
On Wed, Nov 16, 2022 at 11:49 AM hev <r@xxxxxx> wrote:

Hello Peter,

I see a random crash issue  on the LoongArch system, that is caused by
commit 0ccf7f1 ("mm/thp: carry over dirty bit when thp splits on
pmd").

Now, the thing is already resolved. The root cause is arch's mkdirty
is set hardware writable bit in unconditional. That breaks
write-protect and then breaks COW.

Ehm, does this imply that

pte = maybe_mkwrite(pte_mkdirty(pte), vma);

will result in a writable PTE, even though the VMA does not include VM_WRITE?

That would be really broken.

--
Thanks,

David / dhildenb




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