Re: [PATCH v5 19/25] arm64/mm: Wire up PTE_CONT for user mappings
From: David Hildenbrand <hidden>
Date: 2024-02-12 13:54:33
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quoted
If so, I wonder if we could instead do that comparison modulo the access/dirty bits,I think that would work - but will need to think a bit more on it.quoted
and leave ptep_get_lockless() only reading a single entry?I think we will need to do something a bit less fragile. ptep_get() does collect the access/dirty bits so its confusing if ptep_get_lockless() doesn't IMHO. So we will likely want to rename the function and make its documentation explicit that it does not return those bits. ptep_get_lockless_noyoungdirty()? yuk... Any ideas? Of course if I could convince you the current implementation is safe, I might be able to sidestep this optimization until a later date?
As discussed (and pointed out abive), there might be quite some callsites where we don't really care about uptodate accessed/dirty bits -- where ptep_get() is used nowadays. One way to approach that I had in mind was having an explicit interface: ptep_get() ptep_get_uptodate() ptep_get_lockless() ptep_get_lockless_uptodate() Especially the last one might not be needed. Futher, "uptodate" might not be the best choice because of PageUptodate() and friends. But it's better than "youngdirty"/"noyoungdirty" IMHO. Of course, any such changes require care and are better done one step at at time separately. -- Cheers, David / dhildenb _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel