linux-stable.git/mm/memory.c, branch v3.16

mm: debugfs: move rounddown_pow_of_two() out from do_fault path

2014-07-31T00:16:13+00:00

do_fault_around() expects fault_around_bytes rounded down to nearest page
order.  Instead of calling rounddown_pow_of_two every time in
fault_around_pages()/fault_around_mask() we could do round down when user
changes fault_around_bytes via debugfs interface.

This also fixes bug when user set fault_around_bytes to 0.  Result of
rounddown_pow_of_two(0) is not defined, therefore fault_around_bytes == 0
doesn't work without this patch.

Let's set fault_around_bytes to PAGE_SIZE if user sets to something less
than PAGE_SIZE

[akpm@linux-foundation.org: tweak code layout]
Fixes: a9b0f861("mm: nominate faultaround area in bytes rather than page order")
Signed-off-by: Andrey Ryabinin 
Reported-by: Sasha Levin 
Acked-by: Kirill A. Shutemov 
Cc: 	[3.15.x]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: do not call do_fault_around for non-linear fault

2014-07-23T22:10:54+00:00

Ingo Korb reported that "repeated mapping of the same file on tmpfs
using remap_file_pages sometimes triggers a BUG at mm/filemap.c:202 when
the process exits".

He bisected the bug to d7c1755179b8 ("mm: implement ->map_pages for
shmem/tmpfs"), although the bug was actually added by commit
8c6e50b0290c ("mm: introduce vm_ops->map_pages()").

The problem is caused by calling do_fault_around for a _non-linear_
fault.  In this case pgoff is shifted and might become negative during
calculation.

Faulting around non-linear page-fault makes no sense and breaks the
logic in do_fault_around because pgoff is shifted.

Signed-off-by: Konstantin Khlebnikov 
Reported-by: Ingo Korb 
Tested-by: Ingo Korb 
Cc: Hugh Dickins 
Cc: Sasha Levin 
Cc: Dave Jones 
Cc: Ning Qu 
Cc: "Kirill A. Shutemov" 
Cc: 	[3.15.x]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: document do_fault_around() feature

2014-06-04T23:54:12+00:00

Some clarification on how faultaround works.

[akpm@linux-foundation.org: tweak comment text]
Signed-off-by: Kirill A. Shutemov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: nominate faultaround area in bytes rather than page order

2014-06-04T23:54:12+00:00

There is evidencs that the faultaround feature is less relevant on
architectures with page size bigger then 4k.  Which makes sense since page
fault overhead per byte of mapped area should be less there.

Let's rework the feature to specify faultaround area in bytes instead of
page order.  It's 64 kilobytes for now.

The patch effectively disables faultaround on architectures with page size
>= 64k (like ppc64).

It's possible that some other size of faultaround area is relevant for a
platform.  We can expose `fault_around_bytes' variable to arch-specific
code once such platforms will be found.

Signed-off-by: Kirill A. Shutemov 
Cc: Rusty Russell 
Cc: Hugh Dickins 
Cc: Madhavan Srinivasan 
Cc: Benjamin Herrenschmidt 
Cc: Paul Mackerras 
Cc: Rik van Riel 
Cc: Mel Gorman 
Cc: Andi Kleen 
Cc: Peter Zijlstra 
Cc: Ingo Molnar 
Cc: Dave Hansen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: fix typo in comment in do_fault_around()

2014-06-04T23:54:11+00:00

Signed-off-by: Kirill A. Shutemov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: move get_user_pages()-related code to separate file

2014-06-04T23:54:04+00:00

mm/memory.c is overloaded: over 4k lines. get_user_pages() code is
pretty much self-contained let's move it to separate file.

No other changes made.

Signed-off-by: Kirill A. Shutemov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

x86: define _PAGE_NUMA by reusing software bits on the PMD and PTE levels

2014-06-04T23:53:55+00:00

_PAGE_NUMA is currently an alias of _PROT_PROTNONE to trap NUMA hinting
faults on x86.  Care is taken such that _PAGE_NUMA is used only in
situations where the VMA flags distinguish between NUMA hinting faults
and prot_none faults.  This decision was x86-specific and conceptually
it is difficult requiring special casing to distinguish between PROTNONE
and NUMA ptes based on context.

Fundamentally, we only need the _PAGE_NUMA bit to tell the difference
between an entry that is really unmapped and a page that is protected
for NUMA hinting faults as if the PTE is not present then a fault will
be trapped.

Swap PTEs on x86-64 use the bits after _PAGE_GLOBAL for the offset.
This patch shrinks the maximum possible swap size and uses the bit to
uniquely distinguish between NUMA hinting ptes and swap ptes.

Signed-off-by: Mel Gorman 
Cc: David Vrabel 
Cc: Ingo Molnar 
Cc: Peter Anvin 
Cc: Fengguang Wu 
Cc: Linus Torvalds 
Cc: Steven Noonan 
Cc: Rik van Riel 
Cc: Peter Zijlstra 
Cc: Andrea Arcangeli 
Cc: Dave Hansen 
Cc: Srikar Dronamraju 
Cc: Cyrill Gorcunov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'v3.15-rc6' into sched/core, to pick up the latest fixes

2014-05-22T08:28:56+00:00

Signed-off-by: Ingo Molnar

mm/numa: Remove BUG_ON() in __handle_mm_fault()

2014-05-07T11:33:48+00:00

Changing PTEs and PMDs to pte_numa & pmd_numa is done with the
mmap_sem held for reading, which means a pmd can be instantiated
and turned into a numa one while __handle_mm_fault() is examining
the value of old_pmd.

If that happens, __handle_mm_fault() should just return and let
the page fault retry, instead of throwing an oops. This is
handled by the test for pmd_trans_huge(*pmd) below.

Signed-off-by: Rik van Riel 
Reviewed-by: Naoya Horiguchi 
Reported-by: Sunil Pandey 
Signed-off-by: Peter Zijlstra 
Cc: Andrew Morton 
Cc: Johannes Weiner 
Cc: Kirill A. Shutemov 
Cc: Linus Torvalds 
Cc: Mel Gorman 
Cc: linux-mm@kvack.org
Cc: lwoodman@redhat.com
Cc: dave.hansen@intel.com
Link: http://lkml.kernel.org/r/20140429153615.2d72098e@annuminas.surriel.com
Signed-off-by: Ingo Molnar

mm: split 'tlb_flush_mmu()' into tlb flushing and memory freeing parts

2014-04-25T23:05:40+00:00

The mmu-gather operation 'tlb_flush_mmu()' has done two things: the
actual tlb flush operation, and the batched freeing of the pages that
the TLB entries pointed at.

This splits the operation into separate phases, so that the forced
batched flushing done by zap_pte_range() can now do the actual TLB flush
while still holding the page table lock, but delay the batched freeing
of all the pages to after the lock has been dropped.

This in turn allows us to avoid a race condition between
set_page_dirty() (as called by zap_pte_range() when it finds a dirty
shared memory pte) and page_mkclean(): because we now flush all the
dirty page data from the TLB's while holding the pte lock,
page_mkclean() will be held up walking the (recently cleaned) page
tables until after the TLB entries have been flushed from all CPU's.

Reported-by: Benjamin Herrenschmidt 
Tested-by: Dave Hansen 
Acked-by: Hugh Dickins 
Cc: Peter Zijlstra 
Cc: Russell King - ARM Linux 
Cc: Tony Luck 
Signed-off-by: Linus Torvalds