Messages in this thread | | | Date | Tue, 21 May 2002 21:04:03 -0700 (PDT) | From | Linus Torvalds <> | Subject | Re: Make 2.5.17 TLB even more friendlier |
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On Wed, 22 May 2002, Paul Mackerras wrote: > > It seems to me that there is a race in this code in zap_pte_range, > because there is a gap between when we read the pte and when we clear > it:
Yes and no.
There is a race, and yes, another thread might mark it dirty.
However, I've not decided whether we care about it yet. I think we _do_ care, for people doing strange things with their own internal VM management using mmap/munmap of shared mappings, but on the other hand it _is_ fairly expensive to do a "ptep_get_and_clear()".
> Shouldn't we do this as "pte = ptep_get_and_clear(ptep)", at least in > the case where we are unmapping stuff?
Yeah, I want to do it, but I also would really want to avoid the overhead for the exit case. Which is another reason I'd like to have exit() not use zap_page_range() at all.
But I'll make that change now, so that we don't lose it. We should just remember to not do it if we split up exit.
Linus
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