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  1. 11 12月, 2012 3 次提交
    • L
      mm: mempolicy: Check for misplaced page · 771fb4d8
      由 Lee Schermerhorn 提交于 
      This patch provides a new function to test whether a page resides
on a node that is appropriate for the mempolicy for the vma and
address where the page is supposed to be mapped.  This involves
looking up the node where the page belongs.  So, the function
returns that node so that it may be used to allocated the page
without consulting the policy again.

A subsequent patch will call this function from the fault path.
Because of this, I don't want to go ahead and allocate the page, e.g.,
via alloc_page_vma() only to have to free it if it has the correct
policy.  So, I just mimic the alloc_page_vma() node computation
logic--sort of.

Note:  we could use this function to implement a MPOL_MF_STRICT
behavior when migrating pages to match mbind() mempolicy--e.g.,
to ensure that pages in an interleaved range are reinterleaved
rather than left where they are when they reside on any page in
the interleave nodemask.
Signed-off-by: NLee Schermerhorn <lee.schermerhorn@hp.com>
Reviewed-by: NRik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
[ Added MPOL_F_LAZY to trigger migrate-on-fault;
  simplified code now that we don't have to bother
  with special crap for interleaved ]
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NMel Gorman <mgorman@suse.de>
      771fb4d8
    • L
      mm: mempolicy: Add MPOL_NOOP · d3a71033
      由 Lee Schermerhorn 提交于 
      This patch augments the MPOL_MF_LAZY feature by adding a "NOOP" policy
to mbind().  When the NOOP policy is used with the 'MOVE and 'LAZY
flags, mbind() will map the pages PROT_NONE so that they will be
migrated on the next touch.

This allows an application to prepare for a new phase of operation
where different regions of shared storage will be assigned to
worker threads, w/o changing policy.  Note that we could just use
"default" policy in this case.  However, this also allows an
application to request that pages be migrated, only if necessary,
to follow any arbitrary policy that might currently apply to a
range of pages, without knowing the policy, or without specifying
multiple mbind()s for ranges with different policies.

[ Bug in early version of mpol_parse_str() reported by Fengguang Wu. ]
Bug-Reported-by: NReported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NLee Schermerhorn <lee.schermerhorn@hp.com>
Reviewed-by: NRik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NMel Gorman <mgorman@suse.de>
      d3a71033
    • P
      mm: mempolicy: Make MPOL_LOCAL a real policy · 479e2802
      由 Peter Zijlstra 提交于 
      Make MPOL_LOCAL a real and exposed policy such that applications that
relied on the previous default behaviour can explicitly request it.
Requested-by: NChristoph Lameter <cl@linux.com>
Reviewed-by: NRik van Riel <riel@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@kernel.org>
Signed-off-by: NMel Gorman <mgorman@suse.de>
      479e2802
  3. 17 11月, 2012 1 次提交
  5. 09 11月, 2012 1 次提交
    • A
      revert "epoll: support for disabling items, and a self-test app" · a80a6b85
      由 Andrew Morton 提交于 
      Revert commit 03a7beb5 ("epoll: support for disabling items, and a
self-test app") pending resolution of the issues identified by Michael
Kerrisk, copied below.

We'll revisit this for 3.8.

: I've taken a look at this patch as it currently stands in 3.7-rc1, and
: done a bit of testing. (By the way, the test program
: tools/testing/selftests/epoll/test_epoll.c does not compile...)
:
: There are one or two places where the behavior seems a little strange,
: so I have a question or two at the end of this mail. But other than
: that, I want to check my understanding so that the interface can be
: correctly documented.
:
: Just to go though my understanding, the problem is the following
: scenario in a multithreaded application:
:
: 1. Multiple threads are performing epoll_wait() operations,
:    and maintaining a user-space cache that contains information
:    corresponding to each file descriptor being monitored by
:    epoll_wait().
:
: 2. At some point, a thread wants to delete (EPOLL_CTL_DEL)
:    a file descriptor from the epoll interest list, and
:    delete the corresponding record from the user-space cache.
:
: 3. The problem with (2) is that some other thread may have
:    previously done an epoll_wait() that retrieved information
:    about the fd in question, and may be in the middle of using
:    information in the cache that relates to that fd. Thus,
:    there is a potential race.
:
: 4. The race can't solved purely in user space, because doing
:    so would require applying a mutex across the epoll_wait()
:    call, which would of course blow thread concurrency.
:
: Right?
:
: Your solution is the EPOLL_CTL_DISABLE operation. I want to
: confirm my understanding about how to use this flag, since
: the description that has accompanied the patches so far
: has been a bit sparse
:
: 0. In the scenario you're concerned about, deleting a file
:    descriptor means (safely) doing the following:
:    (a) Deleting the file descriptor from the epoll interest list
:        using EPOLL_CTL_DEL
:    (b) Deleting the corresponding record in the user-space cache
:
: 1. It's only meaningful to use this EPOLL_CTL_DISABLE in
:    conjunction with EPOLLONESHOT.
:
: 2. Using EPOLL_CTL_DISABLE without using EPOLLONESHOT in
:    conjunction is a logical error.
:
: 3. The correct way to code multithreaded applications using
:    EPOLL_CTL_DISABLE and EPOLLONESHOT is as follows:
:
:    a. All EPOLL_CTL_ADD and EPOLL_CTL_MOD operations should
:       should EPOLLONESHOT.
:
:    b. When a thread wants to delete a file descriptor, it
:       should do the following:
:
:       [1] Call epoll_ctl(EPOLL_CTL_DISABLE)
:       [2] If the return status from epoll_ctl(EPOLL_CTL_DISABLE)
:           was zero, then the file descriptor can be safely
:           deleted by the thread that made this call.
:       [3] If the epoll_ctl(EPOLL_CTL_DISABLE) fails with EBUSY,
:           then the descriptor is in use. In this case, the calling
:           thread should set a flag in the user-space cache to
:           indicate that the thread that is using the descriptor
:           should perform the deletion operation.
:
: Is all of the above correct?
:
: The implementation depends on checking on whether
: (events & ~EP_PRIVATE_BITS) == 0
: This replies on the fact that EPOLL_CTL_AD and EPOLL_CTL_MOD always
: set EPOLLHUP and EPOLLERR in the 'events' mask, and EPOLLONESHOT
: causes those flags (as well as all others in ~EP_PRIVATE_BITS) to be
: cleared.
:
: A corollary to the previous paragraph is that using EPOLL_CTL_DISABLE
: is only useful in conjunction with EPOLLONESHOT. However, as things
: stand, one can use EPOLL_CTL_DISABLE on a file descriptor that does
: not have EPOLLONESHOT set in 'events' This results in the following
: (slightly surprising) behavior:
:
: (a) The first call to epoll_ctl(EPOLL_CTL_DISABLE) returns 0
:     (the indicator that the file descriptor can be safely deleted).
: (b) The next call to epoll_ctl(EPOLL_CTL_DISABLE) fails with EBUSY.
:
: This doesn't seem particularly useful, and in fact is probably an
: indication that the user made a logic error: they should only be using
: epoll_ctl(EPOLL_CTL_DISABLE) on a file descriptor for which
: EPOLLONESHOT was set in 'events'. If that is correct, then would it
: not make sense to return an error to user space for this case?

Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: "Paton J. Lewis" <palewis@adobe.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      a80a6b85
  7. 23 10月, 2012 1 次提交
  9. 17 10月, 2012 5 次提交
  11. 13 10月, 2012 2 次提交
  13. 12 10月, 2012 1 次提交
  15. 11 10月, 2012 1 次提交
  17. 09 10月, 2012 19 次提交
  19. 05 10月, 2012 2 次提交
  21. 03 10月, 2012 3 次提交