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  1. 05 8月, 2010 1 次提交
    • J
      mm,kdb,kgdb: Add a debug reference for the kdb kmap usage · eac79005
      由 Jason Wessel 提交于 
      The kdb kmap should never get used outside of the kernel debugger
exception context.

Signed-off-by: Jason Wessel<jason.wessel@windriver.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Ingo Molnar <mingo@elte.hu>
CC: linux-mm@kvack.org
      eac79005
  3. 25 5月, 2010 1 次提交
  5. 05 2月, 2010 1 次提交
  7. 10 11月, 2009 2 次提交
  9. 16 6月, 2009 1 次提交
  11. 01 4月, 2009 1 次提交
  13. 16 3月, 2009 1 次提交
    • N
      highmem: atomic highmem kmap page pinning · 3297e760
      由 Nicolas Pitre 提交于 
      Most ARM machines have a non IO coherent cache, meaning that the
dma_map_*() set of functions must clean and/or invalidate the affected
memory manually before DMA occurs.  And because the majority of those
machines have a VIVT cache, the cache maintenance operations must be
performed using virtual
addresses.

When a highmem page is kunmap'd, its mapping (and cache) remains in place
in case it is kmap'd again. However if dma_map_page() is then called with
such a page, some cache maintenance on the remaining mapping must be
performed. In that case, page_address(page) is non null and we can use
that to synchronize the cache.

It is unlikely but still possible for kmap() to race and recycle the
virtual address obtained above, and use it for another page before some
on-going cache invalidation loop in dma_map_page() is done. In that case,
the new mapping could end up with dirty cache lines for another page,
and the unsuspecting cache invalidation loop in dma_map_page() might
simply discard those dirty cache lines resulting in data loss.

For example, let's consider this sequence of events:

	- dma_map_page(..., DMA_FROM_DEVICE) is called on a highmem page.

	-->	- vaddr = page_address(page) is non null. In this case
		it is likely that the page has valid cache lines
		associated with vaddr. Remember that the cache is VIVT.

		-->	for (i = vaddr; i < vaddr + PAGE_SIZE; i += 32)
				invalidate_cache_line(i);

	*** preemption occurs in the middle of the loop above ***

	- kmap_high() is called for a different page.

	-->	- last_pkmap_nr wraps to zero and flush_all_zero_pkmaps()
		  is called.  The pkmap_count value for the page passed
		  to dma_map_page() above happens to be 1, so the page
		  is unmapped.  But prior to that, flush_cache_kmaps()
		  cleared the cache for it.  So far so good.

		- A fresh pkmap entry is assigned for this kmap request.
		  The Murphy law says this pkmap entry will eventually
		  happen to use the same vaddr as the one which used to
		  belong to the other page being processed by
		  dma_map_page() in the preempted thread above.

	- The kmap_high() caller start dirtying the cache using the
	  just assigned virtual mapping for its page.

	*** the first thread is rescheduled ***

			- The for(...) loop is resumed, but now cached
			  data belonging to a different physical page is
			  being discarded !

And this is not only a preemption issue as ARM can be SMP as well,
making the above scenario just as likely. Hence the need for some kind
of pkmap page pinning which can be used in any context, primarily for
the benefit of dma_map_page() on ARM.

This provides the necessary interface to cope with the above issue if
ARCH_NEEDS_KMAP_HIGH_GET is defined, otherwise the resulting code is
unchanged.
Signed-off-by: NNicolas Pitre <nico@marvell.com>
Reviewed-by: NMinChan Kim <minchan.kim@gmail.com>
Acked-by: NAndrew Morton <akpm@linux-foundation.org>
      3297e760
  15. 15 8月, 2008 1 次提交
    • N
      x86, pat: avoid highmem cache attribute aliasing · 5843d9a4
      由 Nick Piggin 提交于 
      Highmem code can leave ptes and tlb entries around for a given page even after
kunmap, and after it has been freed.

>From what I can gather, the PAT code may change the cache attributes of
arbitrary physical addresses (ie. including highmem pages), which would result
in aliases in the case that it operates on one of these lazy tlb highmem
pages.

Flushing kmaps should solve the problem.

I've also just added code for conditional flushing if we haven't got
any dangling highmem aliases -- this should help performance if we
change page attributes frequently or systems that aren't using much
highmem pages (eg. if < 4G RAM). Should be turned into 2 patches, but
just for RFC...
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      5843d9a4
  17. 20 7月, 2008 1 次提交
  19. 20 3月, 2008 1 次提交
  21. 06 2月, 2008 1 次提交
  23. 18 7月, 2007 1 次提交
    • M
      Create the ZONE_MOVABLE zone · 2a1e274a
      由 Mel Gorman 提交于 
      The following 8 patches against 2.6.20-mm2 create a zone called ZONE_MOVABLE
that is only usable by allocations that specify both __GFP_HIGHMEM and
__GFP_MOVABLE.  This has the effect of keeping all non-movable pages within a
single memory partition while allowing movable allocations to be satisfied
from either partition.  The patches may be applied with the list-based
anti-fragmentation patches that groups pages together based on mobility.

The size of the zone is determined by a kernelcore= parameter specified at
boot-time.  This specifies how much memory is usable by non-movable
allocations and the remainder is used for ZONE_MOVABLE.  Any range of pages
within ZONE_MOVABLE can be released by migrating the pages or by reclaiming.

When selecting a zone to take pages from for ZONE_MOVABLE, there are two
things to consider.  First, only memory from the highest populated zone is
used for ZONE_MOVABLE.  On the x86, this is probably going to be ZONE_HIGHMEM
but it would be ZONE_DMA on ppc64 or possibly ZONE_DMA32 on x86_64.  Second,
the amount of memory usable by the kernel will be spread evenly throughout
NUMA nodes where possible.  If the nodes are not of equal size, the amount of
memory usable by the kernel on some nodes may be greater than others.

By default, the zone is not as useful for hugetlb allocations because they are
pinned and non-migratable (currently at least).  A sysctl is provided that
allows huge pages to be allocated from that zone.  This means that the huge
page pool can be resized to the size of ZONE_MOVABLE during the lifetime of
the system assuming that pages are not mlocked.  Despite huge pages being
non-movable, we do not introduce additional external fragmentation of note as
huge pages are always the largest contiguous block we care about.

Credit goes to Andy Whitcroft for catching a large variety of problems during
review of the patches.

This patch creates an additional zone, ZONE_MOVABLE.  This zone is only usable
by allocations which specify both __GFP_HIGHMEM and __GFP_MOVABLE.  Hot-added
memory continues to be placed in their existing destination as there is no
mechanism to redirect them to a specific zone.

[y-goto@jp.fujitsu.com: Fix section mismatch of memory hotplug related code]
[akpm@linux-foundation.org: various fixes]
Signed-off-by: NMel Gorman <mel@csn.ul.ie>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: NYasunori Goto <y-goto@jp.fujitsu.com>
Cc: William Lee Irwin III <wli@holomorphy.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      2a1e274a
  25. 03 5月, 2007 1 次提交
    • J
      [PATCH] i386: PARAVIRT: add kmap_atomic_pte for mapping highpte pages · ce6234b5
      由 Jeremy Fitzhardinge 提交于 
      Xen and VMI both have special requirements when mapping a highmem pte
page into the kernel address space.  These can be dealt with by adding
a new kmap_atomic_pte() function for mapping highptes, and hooking it
into the paravirt_ops infrastructure.

Xen specifically wants to map the pte page RO, so this patch exposes a
helper function, kmap_atomic_prot, which maps the page with the
specified page protections.

This also adds a kmap_flush_unused() function to clear out the cached
kmap mappings.  Xen needs this to clear out any potential stray RW
mappings of pages which will become part of a pagetable.

[ Zach - vmi.c will need some attention after this patch.  It wasn't
  immediately obvious to me what needs to be done. ]
Signed-off-by: NJeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Cc: Zachary Amsden <zach@vmware.com>
      ce6234b5
  27. 12 2月, 2007 1 次提交
  29. 01 10月, 2006 1 次提交
  31. 26 9月, 2006 1 次提交
  33. 01 7月, 2006 1 次提交
  35. 02 4月, 2006 1 次提交
  37. 27 3月, 2006 1 次提交
  39. 24 3月, 2006 1 次提交
  41. 28 10月, 2005 1 次提交
  43. 09 10月, 2005 1 次提交
  45. 01 5月, 2005 1 次提交
  47. 17 4月, 2005 1 次提交
    • L
      Linux-2.6.12-rc2 · 1da177e4
      由 Linus Torvalds 提交于 
      Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
      1da177e4