DragonFly commits List (threaded) for 2012-08
git: kernel - Fix pmap_remove() issue.
Author: Matthew Dillon <email@example.com>
Date: Thu Aug 23 20:44:53 2012 -0700
kernel - Fix pmap_remove() issue.
* When the inner loop of pmap_remove() broke out due to pmap_remove_pte()
blocking it 'jumped' the sindex to pdnxt, thus any remaining pages in
that page table page would get skipped.
* pmap_remove_pte() and friends used to return non-zero if they 'blocked'.
Unfortunately they could actually block whether they returned 0 or non-zero,
causing the problem. Remove the check entirely.
* Adjust misc functions which we no longer need the return value for.
* I don't know if this had anything to do with the wire_count panic.
The failure mode should have been caught by numerous other assertions
in the code but wasn't. get_ptbase() relies on a test of pmap->pm_cached
to determine if a page directory page mapping changes so it should not
have been possible for it to continue the loop and access a stale ptep.
If it were possible it might account for a wire_count panic later on but
it doesn't seem like it should be possible.
Summary of changes:
sys/platform/pc32/i386/pmap.c | 94 +++++++++++++++++++---------------------
1 files changed, 45 insertions(+), 49 deletions(-)
DragonFly BSD source repository