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Kirill A. Shutemov ced108037c thp: fix MADV_DONTNEED vs. numa balancing race
In case prot_numa, we are under down_read(mmap_sem).  It's critical to
not clear pmd intermittently to avoid race with MADV_DONTNEED which is
also under down_read(mmap_sem):

	CPU0:				CPU1:
				change_huge_pmd(prot_numa=1)
				 pmdp_huge_get_and_clear_notify()
madvise_dontneed()
 zap_pmd_range()
  pmd_trans_huge(*pmd) == 0 (without ptl)
  // skip the pmd
				 set_pmd_at();
				 // pmd is re-established

The race makes MADV_DONTNEED miss the huge pmd and don't clear it
which may break userspace.

Found by code analysis, never saw triggered.

Link: http://lkml.kernel.org/r/20170302151034.27829-3-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-04-13 18:24:20 -07:00
arch Merge branch 'fixes' of git://git.armlinux.org.uk/~rmk/linux-arm 2017-04-09 09:05:25 -07:00
block
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Documentation Driver core fixes for 4.11-rc6 2017-04-09 09:03:51 -07:00
drivers Two pin control fixes arriving late: 2017-04-13 09:08:29 -07:00
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fs Merge branch 'for-next' of git://git.samba.org/sfrench/cifs-2.6 2017-04-09 09:10:02 -07:00
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kernel Merge branch 'stable-4.11' of git://git.infradead.org/users/pcmoore/audit 2017-04-12 00:02:33 -07:00
lib
mm thp: fix MADV_DONTNEED vs. numa balancing race 2017-04-13 18:24:20 -07:00
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MAINTAINERS Driver core fixes for 4.11-rc6 2017-04-09 09:03:51 -07:00
Makefile Linux 4.11-rc6 2017-04-09 09:49:44 -07:00
README

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.