Subject: Re: pmap_unwire: wiring for pmap 0xfoo va 0xbar didn't change!
To: None <>
From: YAMAMOTO Takashi <>
List: current-users
Date: 08/29/2005 11:10:16

> the attached patch fixes this problem, by removing an optimization that would
> incorrectly skip TLB flushes in some cases where a pmap mapping is replaced
> with another mapping of the same page, but with different permissions.
> skipping the TLB flush is incorrect if the new entry is supposed to be wired,
> since a stale read-only entry that's supposed to be writable might cause
> a fault which would replace the wired entry with a non-wired entry
> (which is what causes the warning messages).  increasing the permissions
> an entry is not a common occurance, so it doesn't seem worthwhile to
> complicate the code with the optimization, thus the proposal to just
> remove it rather than fix it.
> any objections?
> -Chuck

i have no objection.

but isn't it more generic uvm_vslock/unlock problem?
ie. anyone can modify the mapping between uvm_vslock and uvm_vsunlock.