linux.git/mm/pgtable-generic.c, branch v4.4

mm,thp: introduce flush_pmd_tlb_range

2015-10-17T12:18:20+00:00

ARCHes with special requirements for evicting THP backing TLB entries
can implement this.

Otherwise also, it can help optimize TLB flush in THP regime.
stock flush_tlb_range() typically has optimization to nuke the entire
TLB if flush span is greater than a certain threshhold, which will
likely be true for a single huge page. Thus a single thp flush will
invalidate the entrire TLB which is not desirable.

e.g. see arch/arc: flush_pmd_tlb_range

Acked-by: Kirill A. Shutemov 
Link: http://lkml.kernel.org/r/20151009100816.GC7873@node
Signed-off-by: Vineet Gupta

mm,thp: reduce ifdef'ery for THP in generic code

2015-10-17T12:18:20+00:00

- pgtable-generic.c: Fold individual #ifdef for each helper into a top
  level #ifdef. Makes code more readable

- Converted the stub helpers for !THP to BUILD_BUG() vs. runtime BUG()

Acked-by: Kirill A. Shutemov 
Link: http://lkml.kernel.org/r/20151009133450.GA8597@node
Signed-off-by: Vineet Gupta

mm: group pte related helpers together

2015-10-17T12:18:19+00:00

This reduces/simplifies the diff for the next patch which moves THP
specific code.

No semantical changes !

Acked-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com
Link: http://lkml.kernel.org/r/1442918096-17454-9-git-send-email-vgupta@synopsys.com
Signed-off-by: Vineet Gupta

mm: clarify that the function operates on hugepage pte

2015-06-25T00:49:44+00:00

We have confusing functions to clear pmd, pmd_clear_* and pmd_clear.  Add
_huge_ to pmdp_clear functions so that we are clear that they operate on
hugepage pte.

We don't bother about other functions like pmdp_set_wrprotect,
pmdp_clear_flush_young, because they operate on PTE bits and hence
indicate they are operating on hugepage ptes

Signed-off-by: Aneesh Kumar K.V 
Acked-by: Kirill A. Shutemov 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Michael Ellerman 
Cc: Andrea Arcangeli 
Cc: Martin Schwidefsky 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

powerpc/mm: use generic version of pmdp_clear_flush()

2015-06-25T00:49:44+00:00

Also move the pmd_trans_huge check to generic code.

Signed-off-by: Aneesh Kumar K.V 
Acked-by: Kirill A. Shutemov 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Michael Ellerman 
Cc: Andrea Arcangeli 
Cc: Martin Schwidefsky 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: convert p[te|md]_mknonnuma and remaining page table manipulations

2015-02-13T02:54:08+00:00

With PROT_NONE, the traditional page table manipulation functions are
sufficient.

[andre.przywara@arm.com: fix compiler warning in pmdp_invalidate()]
[akpm@linux-foundation.org: fix build with STRICT_MM_TYPECHECKS]
Signed-off-by: Mel Gorman 
Acked-by: Linus Torvalds 
Acked-by: Aneesh Kumar 
Tested-by: Sasha Levin 
Cc: Benjamin Herrenschmidt 
Cc: Dave Jones 
Cc: Hugh Dickins 
Cc: Ingo Molnar 
Cc: Kirill Shutemov 
Cc: Paul Mackerras 
Cc: Rik van Riel 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: convert p[te|md]_numa users to p[te|md]_protnone_numa

2015-02-13T02:54:08+00:00

Convert existing users of pte_numa and friends to the new helper.  Note
that the kernel is broken after this patch is applied until the other page
table modifiers are also altered.  This patch layout is to make review
easier.

Signed-off-by: Mel Gorman 
Acked-by: Linus Torvalds 
Acked-by: Aneesh Kumar 
Acked-by: Benjamin Herrenschmidt 
Tested-by: Sasha Levin 
Cc: Dave Jones 
Cc: Hugh Dickins 
Cc: Ingo Molnar 
Cc: Kirill Shutemov 
Cc: Paul Mackerras 
Cc: Rik van Riel 
Cc: Sasha Levin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: actually clear pmd_numa before invalidating

2014-08-29T23:28:15+00:00

Commit 67f87463d3a3 ("mm: clear pmd_numa before invalidating") cleared
the NUMA bit in a copy of the PMD entry, but then wrote back the
original

Signed-off-by: Matthew Wilcox 
Acked-by: Mel Gorman 
Reviewed-by: Rik van Riel 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: fix TLB flush race between migration, and change_protection_range

2013-12-19T03:04:51+00:00

There are a few subtle races, between change_protection_range (used by
mprotect and change_prot_numa) on one side, and NUMA page migration and
compaction on the other side.

The basic race is that there is a time window between when the PTE gets
made non-present (PROT_NONE or NUMA), and the TLB is flushed.

During that time, a CPU may continue writing to the page.

This is fine most of the time, however compaction or the NUMA migration
code may come in, and migrate the page away.

When that happens, the CPU may continue writing, through the cached
translation, to what is no longer the current memory location of the
process.

This only affects x86, which has a somewhat optimistic pte_accessible.
All other architectures appear to be safe, and will either always flush,
or flush whenever there is a valid mapping, even with no permissions
(SPARC).

The basic race looks like this:

CPU A			CPU B			CPU C

						load TLB entry
make entry PTE/PMD_NUMA
			fault on entry
						read/write old page
			start migrating page
			change PTE/PMD to new page
						read/write old page [*]
flush TLB
						reload TLB from new entry
						read/write new page
						lose data

[*] the old page may belong to a new user at this point!

The obvious fix is to flush remote TLB entries, by making sure that
pte_accessible aware of the fact that PROT_NONE and PROT_NUMA memory may
still be accessible if there is a TLB flush pending for the mm.

This should fix both NUMA migration and compaction.

[mgorman@suse.de: fix build]
Signed-off-by: Rik van Riel 
Signed-off-by: Mel Gorman 
Cc: Alex Thorlton 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: clear pmd_numa before invalidating

2013-12-19T03:04:51+00:00

On x86, PMD entries are similar to _PAGE_PROTNONE protection and are
handled as NUMA hinting faults.  The following two page table protection
bits are what defines them

	_PAGE_NUMA:set	_PAGE_PRESENT:clear

A PMD is considered present if any of the _PAGE_PRESENT, _PAGE_PROTNONE,
_PAGE_PSE or _PAGE_NUMA bits are set.  If pmdp_invalidate encounters a
pmd_numa, it clears the present bit leaving _PAGE_NUMA which will be
considered not present by the CPU but present by pmd_present.  The
existing caller of pmdp_invalidate should handle it but it's an
inconsistent state for a PMD.  This patch keeps the state consistent
when calling pmdp_invalidate.

Signed-off-by: Mel Gorman 
Reviewed-by: Rik van Riel 
Cc: Alex Thorlton 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds