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  1. 17 4月, 2008 4 次提交
  3. 04 3月, 2008 1 次提交
  5. 03 3月, 2008 1 次提交
  7. 01 3月, 2008 1 次提交
    • H
      x86: fix pmd_bad and pud_bad to support huge pages · cded932b
      由 Hans Rosenfeld 提交于 
      I recently stumbled upon a problem in the support for huge pages. If a
program using huge pages does not explicitly unmap them, they remain
mapped (and therefore, are lost) after the program exits.

I observed that the free huge page count in /proc/meminfo decreased when
running my program, and it did not increase after the program exited.
After running the program a few times, no more huge pages could be
allocated.

The reason for this seems to be that the x86 pmd_bad and pud_bad
consider pmd/pud entries having the PSE bit set invalid. I think there
is nothing wrong with this bit being set, it just indicates that the
lowest level of translation has been reached. This bit has to be (and
is) checked after the basic validity of the entry has been checked, like
in this fragment from follow_page() in mm/memory.c:

  if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
          goto no_page_table;

  if (pmd_huge(*pmd)) {
          BUG_ON(flags & FOLL_GET);
          page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
          goto out;
  }

Note that this code currently doesn't work as intended if the pmd refers
to a huge page, the pmd_huge() check can not be reached if the page is
huge.

Extending pmd_bad() (and, for future 1GB page support, pud_bad()) to
allow for the PSE bit being set fixes this. For similar reasons,
allowing the NX bit being set is necessary, too. I have seen huge pages
having the NX bit set in their pmd entry, which would cause the same
problem.
Signed-Off-By: NHans Rosenfeld <hans.rosenfeld@amd.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      cded932b
  9. 19 2月, 2008 2 次提交
  11. 04 2月, 2008 2 次提交
  13. 30 1月, 2008 20 次提交
  15. 20 10月, 2007 1 次提交
  17. 17 10月, 2007 1 次提交
  19. 11 10月, 2007 1 次提交
  21. 22 9月, 2007 1 次提交
  23. 23 7月, 2007 1 次提交
    • A
      x86: Fix alternatives and kprobes to remap write-protected kernel text · 19d36ccd
      由 Andi Kleen 提交于 
      Reenable kprobes and alternative patching when the kernel text is write
protected by DEBUG_RODATA

Add a general utility function to change write protected text.  The new
function remaps the code using vmap to write it and takes care of CPU
synchronization.  It also does CLFLUSH to make icache recovery faster.

There are some limitations on when the function can be used, see the
comment.

This is a newer version that also changes the paravirt_ops code.
text_poke also supports multi byte patching now.

Contains bug fixes from Zach Amsden and suggestions from Mathieu
Desnoyers.

Cc: Jan Beulich <jbeulich@novell.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Cc: Zach Amsden <zach@vmware.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      19d36ccd
  25. 22 7月, 2007 1 次提交
  27. 18 7月, 2007 1 次提交
  29. 17 7月, 2007 1 次提交
  31. 17 6月, 2007 1 次提交