svn commit: r269134 - head/sys/vm
Slawa Olhovchenkov
slw at zxy.spb.ru
Tue Jul 29 10:38:15 UTC 2014
On Sat, Jul 26, 2014 at 06:10:18PM +0000, Alan Cox wrote:
> Author: alc
> Date: Sat Jul 26 18:10:18 2014
> New Revision: 269134
> URL: http://svnweb.freebsd.org/changeset/base/269134
>
> Log:
> When unwiring a region of an address space, do not assume that the
> underlying physical pages are mapped by the pmap. If, for example, the
> application has performed an mprotect(..., PROT_NONE) on any part of the
> wired region, then those pages will no longer be mapped by the pmap.
> So, using the pmap to lookup the wired pages in order to unwire them
> doesn't always work, and when it doesn't work wired pages are leaked.
>
> To avoid the leak, introduce and use a new function vm_object_unwire()
> that locates the wired pages by traversing the object and its backing
> objects.
MFC planed?
> At the same time, switch from using pmap_change_wiring() to the recently
> introduced function pmap_unwire() for unwiring the region's mappings.
> pmap_unwire() is faster, because it operates a range of virtual addresses
> rather than a single virtual page at a time. Moreover, by operating on
> a range, it is superpage friendly. It doesn't waste time performing
> unnecessary demotions.
>
> Reported by: markj
> Reviewed by: kib
> Tested by: pho, jmg (arm)
> Sponsored by: EMC / Isilon Storage Division
More information about the svn-src-head
mailing list