Messages in this thread | | | Date | Sun, 12 Oct 2003 18:35:36 -0700 | From | Roland McGrath <> | Subject | Re: [PATCH] report user-readable fixmap area in /proc/PID/maps |
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> This special-casing, and the special-casing in get_user_pages() would go > away if each process had a real VMA for the fixmap area inserted into its > VMA tree.
Agreed.
> Remind me again why we cannot do that?
I don't know any reason to think we cannot. That's not the way it was done when I first looked at fixmap issues, and I try not to rock the boat more than necessary (really!). I know that Ingo had some kernel versions that used a normal vma for it (and randomized the location on each exec), so he certainly managed it. I always assumed that people (i.e. Linus) wouldn't like it because of the overhead in memory and setup time for an extra vma that is identical in every process. Given the constraint that the fixmap area is the last thing in the address space, I imagine that can be mitigated by some magic using a single shared fixmap_vma at the end of everybody's chain. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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