mirror of
https://git.FreeBSD.org/src.git
synced 2024-12-03 09:00:21 +00:00
Mirror of the FreeBSD src repository https://git.FreeBSD.org/src.git .
7eeda22793
Remove the code to dyanmically change the pv_entry limits. Go back to a single fixed kva reservation for pv entries, like was done before when using the uma zone. Go back to never freeing pages back to the free pool after they are no longer used, just like before. This stops the lock order reversal due to aquiring the kernel map lock while pmap was locked. This fixes the recursive panic if invariants are enabled. The problem was that allocating/freeing kva causes vm_map_entry nodes to be allocated/freed. That can recurse back into pmap as new pages are hooked up to kvm and hence all the problem. Allocating/freeing kva indirectly allocate/frees memory. So, by going back to a single fixed size kva block and an index, we avoid the recursion panics and the LOR. The problem is that now with a linear block of kva, we have no mechanism to track holes once pages are freed. UMA has the same problem when using custom object for a zone and a fixed reservation of kva. Simple solutions like having a bitmap would work, but would be very inefficient when there are hundreds of thousands of bits in the map. A first-free pointer is similarly flawed because pages can be freed at random and the first-free pointer would be rewinding huge amounts. If we could allocate memory for tree strucures or an external freelist, that would work. Except we cannot allocate/free memory here because we cannot allocate/free address space to use it in. Anyway, my change here reverts back to the UMA behavior of not freeing pages for now, thereby avoiding holes in the map. ups@ had a truely evil idea that I'll investigate. It should allow freeing unused pages again by giving us a no-cost way to track the holes in the kva block. But in the meantime, this should get people booting with witness and/or invariants again. Footnote: amd64 doesn't have this problem because of the direct map access method. I'd done all my witness/invariants testing there. I'd never considered that the harmless-looking kmem_alloc/kmem_free calls would cause such a problem and it didn't show up on the boot test. |
||
|---|---|---|
| bin | ||
| contrib | ||
| crypto | ||
| etc | ||
| games | ||
| gnu | ||
| include | ||
| kerberos5 | ||
| lib | ||
| libexec | ||
| release | ||
| rescue | ||
| sbin | ||
| secure | ||
| share | ||
| sys | ||
| tools | ||
| usr.bin | ||
| usr.sbin | ||
| COPYRIGHT | ||
| LOCKS | ||
| MAINTAINERS | ||
| Makefile | ||
| Makefile.inc1 | ||
| ObsoleteFiles.inc | ||
| README | ||
| UPDATING | ||
This is the top level of the FreeBSD source directory. This file was last revised on: $FreeBSD$ For copyright information, please see the file COPYRIGHT in this directory (additional copyright information also exists for some sources in this tree - please see the specific source directories for more information). The Makefile in this directory supports a number of targets for building components (or all) of the FreeBSD source tree, the most commonly used one being ``world'', which rebuilds and installs everything in the FreeBSD system from the source tree except the kernel, the kernel-modules and the contents of /etc. The ``buildkernel'' and ``installkernel'' targets build and install the kernel and the modules (see below). Please see the top of the Makefile in this directory for more information on the standard build targets and compile-time flags. Building a kernel is a somewhat more involved process, documentation for which can be found at: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/kernelconfig.html And in the config(8) man page. Note: If you want to build and install the kernel with the ``buildkernel'' and ``installkernel'' targets, you might need to build world before. More information is available in the handbook. The sample kernel configuration files reside in the sys/<arch>/conf sub-directory (assuming that you've installed the kernel sources), the file named GENERIC being the one used to build your initial installation kernel. The file NOTES contains entries and documentation for all possible devices, not just those commonly used. It is the successor of the ancient LINT file, but in contrast to LINT, it is not buildable as a kernel but a pure reference and documentation file. Source Roadmap: --------------- bin System/user commands. contrib Packages contributed by 3rd parties. crypto Cryptography stuff (see crypto/README). etc Template files for /etc. games Amusements. gnu Various commands and libraries under the GNU Public License. Please see gnu/COPYING* for more information. include System include files. kerberos5 Kerberos5 (Heimdal) package. lib System libraries. libexec System daemons. release Release building Makefile & associated tools. rescue Build system for statically linked /rescue utilities. sbin System commands. secure Cryptographic libraries and commands. share Shared resources. sys Kernel sources. tools Utilities for regression testing and miscellaneous tasks. usr.bin User commands. usr.sbin System administration commands. For information on synchronizing your source tree with one or more of the FreeBSD Project's development branches, please see: http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/synching.html