Skip to content

R
raspberrypi-kernel

openeuler / raspberrypi-kernel

通知 13
Star 1
Fork 0
R
raspberrypi-kernel
切换分支/标签
  1. 03 11月, 2011 2 次提交
    • A
      thp: share get_huge_page_tail() · b35a35b5
      由 Andrea Arcangeli 提交于 
      This avoids duplicating the function in every arch gup_fast.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      b35a35b5
    • A
      mm: thp: tail page refcounting fix · 70b50f94
      由 Andrea Arcangeli 提交于 
      Michel while working on the working set estimation code, noticed that
calling get_page_unless_zero() on a random pfn_to_page(random_pfn)
wasn't safe, if the pfn ended up being a tail page of a transparent
hugepage under splitting by __split_huge_page_refcount().

He then found the problem could also theoretically materialize with
page_cache_get_speculative() during the speculative radix tree lookups
that uses get_page_unless_zero() in SMP if the radix tree page is freed
and reallocated and get_user_pages is called on it before
page_cache_get_speculative has a chance to call get_page_unless_zero().

So the best way to fix the problem is to keep page_tail->_count zero at
all times.  This will guarantee that get_page_unless_zero() can never
succeed on any tail page.  page_tail->_mapcount is guaranteed zero and
is unused for all tail pages of a compound page, so we can simply
account the tail page references there and transfer them to
tail_page->_count in __split_huge_page_refcount() (in addition to the
head_page->_mapcount).

While debugging this s/_count/_mapcount/ change I also noticed get_page is
called by direct-io.c on pages returned by get_user_pages.  That wasn't
entirely safe because the two atomic_inc in get_page weren't atomic.  As
opposed to other get_user_page users like secondary-MMU page fault to
establish the shadow pagetables would never call any superflous get_page
after get_user_page returns.  It's safer to make get_page universally safe
for tail pages and to use get_page_foll() within follow_page (inside
get_user_pages()).  get_page_foll() is safe to do the refcounting for tail
pages without taking any locks because it is run within PT lock protected
critical sections (PT lock for pte and page_table_lock for
pmd_trans_huge).

The standard get_page() as invoked by direct-io instead will now take
the compound_lock but still only for tail pages.  The direct-io paths
are usually I/O bound and the compound_lock is per THP so very
finegrined, so there's no risk of scalability issues with it.  A simple
direct-io benchmarks with all lockdep prove locking and spinlock
debugging infrastructure enabled shows identical performance and no
overhead.  So it's worth it.  Ideally direct-io should stop calling
get_page() on pages returned by get_user_pages().  The spinlock in
get_page() is already optimized away for no-THP builds but doing
get_page() on tail pages returned by GUP is generally a rare operation
and usually only run in I/O paths.

This new refcounting on page_tail->_mapcount in addition to avoiding new
RCU critical sections will also allow the working set estimation code to
work without any further complexity associated to the tail page
refcounting with THP.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Reported-by: NMichel Lespinasse <walken@google.com>
Reviewed-by: NMichel Lespinasse <walken@google.com>
Reviewed-by: NMinchan Kim <minchan.kim@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: <stable@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      70b50f94
  3. 02 11月, 2011 24 次提交
  5. 01 11月, 2011 3 次提交
    • B
      i7core_edac: Drop the edac_mce facility · 4140c542
      由 Borislav Petkov 提交于 
      Remove edac_mce pieces and use the normal MCE decoder notifier chain by
retaining the same functionality with considerably less code.
Signed-off-by: NBorislav Petkov <borislav.petkov@amd.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
      4140c542
    • C
      Cross Memory Attach · fcf63409
      由 Christopher Yeoh 提交于 
      The basic idea behind cross memory attach is to allow MPI programs doing
intra-node communication to do a single copy of the message rather than a
double copy of the message via shared memory.

The following patch attempts to achieve this by allowing a destination
process, given an address and size from a source process, to copy memory
directly from the source process into its own address space via a system
call.  There is also a symmetrical ability to copy from the current
process's address space into a destination process's address space.

- Use of /proc/pid/mem has been considered, but there are issues with
  using it:
  - Does not allow for specifying iovecs for both src and dest, assuming
    preadv or pwritev was implemented either the area read from or
  written to would need to be contiguous.
  - Currently mem_read allows only processes who are currently
  ptrace'ing the target and are still able to ptrace the target to read
  from the target. This check could possibly be moved to the open call,
  but its not clear exactly what race this restriction is stopping
  (reason  appears to have been lost)
  - Having to send the fd of /proc/self/mem via SCM_RIGHTS on unix
  domain socket is a bit ugly from a userspace point of view,
  especially when you may have hundreds if not (eventually) thousands
  of processes  that all need to do this with each other
  - Doesn't allow for some future use of the interface we would like to
  consider adding in the future (see below)
  - Interestingly reading from /proc/pid/mem currently actually
  involves two copies! (But this could be fixed pretty easily)

As mentioned previously use of vmsplice instead was considered, but has
problems.  Since you need the reader and writer working co-operatively if
the pipe is not drained then you block.  Which requires some wrapping to
do non blocking on the send side or polling on the receive.  In all to all
communication it requires ordering otherwise you can deadlock.  And in the
example of many MPI tasks writing to one MPI task vmsplice serialises the
copying.

There are some cases of MPI collectives where even a single copy interface
does not get us the performance gain we could.  For example in an
MPI_Reduce rather than copy the data from the source we would like to
instead use it directly in a mathops (say the reduce is doing a sum) as
this would save us doing a copy.  We don't need to keep a copy of the data
from the source.  I haven't implemented this, but I think this interface
could in the future do all this through the use of the flags - eg could
specify the math operation and type and the kernel rather than just
copying the data would apply the specified operation between the source
and destination and store it in the destination.

Although we don't have a "second user" of the interface (though I've had
some nibbles from people who may be interested in using it for intra
process messaging which is not MPI).  This interface is something which
hardware vendors are already doing for their custom drivers to implement
fast local communication.  And so in addition to this being useful for
OpenMPI it would mean the driver maintainers don't have to fix things up
when the mm changes.

There was some discussion about how much faster a true zero copy would
go. Here's a link back to the email with some testing I did on that:

http://marc.info/?l=linux-mm&m=130105930902915&w=2

There is a basic man page for the proposed interface here:

http://ozlabs.org/~cyeoh/cma/process_vm_readv.txt

This has been implemented for x86 and powerpc, other architecture should
mainly (I think) just need to add syscall numbers for the process_vm_readv
and process_vm_writev. There are 32 bit compatibility versions for
64-bit kernels.

For arch maintainers there are some simple tests to be able to quickly
verify that the syscalls are working correctly here:

http://ozlabs.org/~cyeoh/cma/cma-test-20110718.tgzSigned-off-by: NChris Yeoh <yeohc@au1.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Cc: <linux-man@vger.kernel.org>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      fcf63409
    • B
      x86, MCE: Use notifier chain only for MCE decoding · f0cb5452
      由 Borislav Petkov 提交于 
      Drop the edac_mce custom hook in favor of the generic notifier
mechanism. Also, do not log the error to mcelog if the notified agent
was able to decode it.
Signed-off-by: NBorislav Petkov <borislav.petkov@amd.com>
Acked-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>
      f0cb5452
  7. 30 10月, 2011 1 次提交
    • J
      KVM: SVM: Keep intercepting task switching with NPT enabled · f1c1da2b
      由 Jan Kiszka 提交于 
      AMD processors apparently have a bug in the hardware task switching
support when NPT is enabled. If the task switch triggers a NPF, we can
get wrong EXITINTINFO along with that fault. On resume, spurious
exceptions may then be injected into the guest.

We were able to reproduce this bug when our guest triggered #SS and the
handler were supposed to run over a separate task with not yet touched
stack pages.

Work around the issue by continuing to emulate task switches even in
NPT mode.
Signed-off-by: NJan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: NMarcelo Tosatti <mtosatti@redhat.com>
      f1c1da2b
  9. 28 10月, 2011 1 次提交
    • E
      compat: sync compat_stats with statfs. · 1448c721
      由 Eric W. Biederman 提交于 
      This was found by inspection while tracking a similar
bug in compat_statfs64, that has been fixed in mainline
since decemeber.

- This fixes a bug where not all of the f_spare fields
  were cleared on mips and s390.
- Add the f_flags field to struct compat_statfs
- Copy f_flags to userspace in case someone cares.
- Use __clear_user to copy the f_spare field to userspace
  to ensure that all of the elements of f_spare are cleared.
  On some architectures f_spare is has 5 ints and on some
  architectures f_spare only has 4 ints.  Which makes
  the previous technique of clearing each int individually
  broken.

I don't expect anyone actually uses the old statfs system
call anymore but if they do let them benefit from having
the compat and the native version working the same.
Signed-off-by: NEric W. Biederman <ebiederm@xmission.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>
      1448c721
  11. 27 10月, 2011 1 次提交
  13. 25 10月, 2011 1 次提交
    • J
      x86: Fix compilation bug in kprobes' twobyte_is_boostable · 315eb8a2
      由 Josh Stone 提交于 
      When compiling an i386_defconfig kernel with gcc-4.6.1-9.fc15.i686, I
noticed a warning about the asm operand for test_bit in kprobes'
can_boost.  I discovered that this caused only the first long of
twobyte_is_boostable[] to be output.

Jakub filed and fixed gcc PR50571 to correct the warning and this output
issue.  But to solve it for less current gcc, we can make kprobes'
twobyte_is_boostable[] non-const, and it won't be optimized out.

Before:

    CC      arch/x86/kernel/kprobes.o
  In file included from include/linux/bitops.h:22:0,
                   from include/linux/kernel.h:17,
                   from [...]/arch/x86/include/asm/percpu.h:44,
                   from [...]/arch/x86/include/asm/current.h:5,
                   from [...]/arch/x86/include/asm/processor.h:15,
                   from [...]/arch/x86/include/asm/atomic.h:6,
                   from include/linux/atomic.h:4,
                   from include/linux/mutex.h:18,
                   from include/linux/notifier.h:13,
                   from include/linux/kprobes.h:34,
                   from arch/x86/kernel/kprobes.c:43:
  [...]/arch/x86/include/asm/bitops.h: In function ‘can_boost.part.1’:
  [...]/arch/x86/include/asm/bitops.h:319:2: warning: use of memory input
        without lvalue in asm operand 1 is deprecated [enabled by default]

  $ objdump -rd arch/x86/kernel/kprobes.o | grep -A1 -w bt
       551:	0f a3 05 00 00 00 00 	bt     %eax,0x0
                          554: R_386_32	.rodata.cst4

  $ objdump -s -j .rodata.cst4 -j .data arch/x86/kernel/kprobes.o

  arch/x86/kernel/kprobes.o:     file format elf32-i386

  Contents of section .data:
   0000 48000000 00000000 00000000 00000000  H...............
  Contents of section .rodata.cst4:
   0000 4c030000                             L...

Only a single long of twobyte_is_boostable[] is in the object file.

After, without the const on twobyte_is_boostable:

  $ objdump -rd arch/x86/kernel/kprobes.o | grep -A1 -w bt
       551:	0f a3 05 20 00 00 00 	bt     %eax,0x20
                          554: R_386_32	.data

  $ objdump -s -j .rodata.cst4 -j .data arch/x86/kernel/kprobes.o

  arch/x86/kernel/kprobes.o:     file format elf32-i386

  Contents of section .data:
   0000 48000000 00000000 00000000 00000000  H...............
   0010 00000000 00000000 00000000 00000000  ................
   0020 4c030000 0f000200 ffff0000 ffcff0c0  L...............
   0030 0000ffff 3bbbfff8 03ff2ebb 26bb2e77  ....;.......&..w

Now all 32 bytes are output into .data instead.
Signed-off-by: NJosh Stone <jistone@redhat.com>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Jakub Jelinek <jakub@redhat.com>
Cc: stable@kernel.org
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      315eb8a2
  15. 24 10月, 2011 3 次提交
  17. 21 10月, 2011 4 次提交