Re: 2.4.10pre13aa1

Manfred Spraul (
Sun, 23 Sep 2001 11:46:18 +0200

>> with only the dirty bit set? Does somebody know for sure? I can
>> imagine the cpu finding the tlb state writeable, and issuing
>> just a locked bit test and set in the pte without caring to
>> check if the pte is zero or not.
>> If the cpu just set the bit this patch will avoid to lose a shared
>> mapping update. Otherwise it's a safe noop so I keep it applied
>> until this issue is sorted out
>I've tested this on all the machines I could get my hands on, and every
>single CPU will take a page fault if the pte is not present on dirtying
>the page. If people are truely paranoid, then make it a boot time
> assertion.

I don't think that this is a valid argument:
you are testing on i386 and make design decisions for the architecture
independant part.

I'd prefer ptep_get_and_clear_and_flush(), then the arch part can do
what's needed to get the final pte value. (if a single page is modified,
otherwise the arch can define a suitable mmu_gather)


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