linux-toradex.git/mm/sparse.c, branch v4.19-rc1

mm/sparse: delete old sparse_init and enable new one

2018-08-17T23:20:32+00:00

Rename new_sparse_init() to sparse_init() which enables it.  Delete old
sparse_init() and all the code that became obsolete with.

[pasha.tatashin@oracle.com: remove unused sparse_mem_maps_populate_node()]
  Link: http://lkml.kernel.org/r/20180716174447.14529-6-pasha.tatashin@oracle.com
Link: http://lkml.kernel.org/r/20180712203730.8703-6-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin 
Tested-by: Michael Ellerman 	[powerpc]
Tested-by: Oscar Salvador 
Reviewed-by: Oscar Salvador 
Cc: Pasha Tatashin 
Cc: Abdul Haleem 
Cc: Baoquan He 
Cc: Daniel Jordan 
Cc: Dan Williams 
Cc: Dave Hansen 
Cc: David Rientjes 
Cc: Greg Kroah-Hartman 
Cc: Ingo Molnar 
Cc: Jan Kara 
Cc: Jérôme Glisse 
Cc: "Kirill A. Shutemov" 
Cc: Michal Hocko 
Cc: Souptick Joarder 
Cc: Steven Sistare 
Cc: Vlastimil Babka 
Cc: Wei Yang 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/sparse: add new sparse_init_nid() and sparse_init()

2018-08-17T23:20:32+00:00

sparse_init() requires to temporary allocate two large buffers: usemap_map
and map_map.  Baoquan He has identified that these buffers are so large
that Linux is not bootable on small memory machines, such as a kdump boot.
The buffers are especially large when CONFIG_X86_5LEVEL is set, as they
are scaled to the maximum physical memory size.

Baoquan provided a fix, which reduces these sizes of these buffers, but it
is much better to get rid of them entirely.

Add a new way to initialize sparse memory: sparse_init_nid(), which only
operates within one memory node, and thus allocates memory either in large
contiguous block or allocates section by section.  This eliminates the
need for use of temporary buffers.

For simplified bisecting and review temporarly call sparse_init()
new_sparse_init(), the new interface is going to be enabled as well as old
code removed in the next patch.

Link: http://lkml.kernel.org/r/20180712203730.8703-5-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin 
Reviewed-by: Oscar Salvador 
Tested-by: Oscar Salvador 
Tested-by: Michael Ellerman 	[powerpc]
Cc: Pasha Tatashin 
Cc: Abdul Haleem 
Cc: Baoquan He 
Cc: Daniel Jordan 
Cc: Dan Williams 
Cc: Dave Hansen 
Cc: David Rientjes 
Cc: Greg Kroah-Hartman 
Cc: Ingo Molnar 
Cc: Jan Kara 
Cc: Jérôme Glisse 
Cc: "Kirill A. Shutemov" 
Cc: Michal Hocko 
Cc: Souptick Joarder 
Cc: Steven Sistare 
Cc: Vlastimil Babka 
Cc: Wei Yang 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/sparse: move buffer init/fini to the common place

2018-08-17T23:20:32+00:00

Now that both variants of sparse memory use the same buffers to populate
memory map, we can move sparse_buffer_init()/sparse_buffer_fini() to the
common place.

Link: http://lkml.kernel.org/r/20180712203730.8703-4-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin 
Tested-by: Michael Ellerman 	[powerpc]
Tested-by: Oscar Salvador 
Reviewed-by: Andrew Morton 
Cc: Pasha Tatashin 
Cc: Abdul Haleem 
Cc: Baoquan He 
Cc: Daniel Jordan 
Cc: Dan Williams 
Cc: Dave Hansen 
Cc: David Rientjes 
Cc: Greg Kroah-Hartman 
Cc: Ingo Molnar 
Cc: Jan Kara 
Cc: Jérôme Glisse 
Cc: "Kirill A. Shutemov" 
Cc: Michal Hocko 
Cc: Souptick Joarder 
Cc: Steven Sistare 
Cc: Vlastimil Babka 
Cc: Wei Yang 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/sparse: use the new sparse buffer functions in non-vmemmap

2018-08-17T23:20:32+00:00

non-vmemmap sparse also allocated large contiguous chunk of memory, and if
fails falls back to smaller allocations.  Use the same functions to
allocate buffer as the vmemmap-sparse

Link: http://lkml.kernel.org/r/20180712203730.8703-3-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin 
Tested-by: Michael Ellerman 	[powerpc]
Reviewed-by: Oscar Salvador 
Tested-by: Oscar Salvador 
Cc: Pasha Tatashin 
Cc: Abdul Haleem 
Cc: Baoquan He 
Cc: Daniel Jordan 
Cc: Dan Williams 
Cc: Dave Hansen 
Cc: David Rientjes 
Cc: Greg Kroah-Hartman 
Cc: Ingo Molnar 
Cc: Jan Kara 
Cc: Jérôme Glisse 
Cc: "Kirill A. Shutemov" 
Cc: Michal Hocko 
Cc: Souptick Joarder 
Cc: Steven Sistare 
Cc: Vlastimil Babka 
Cc: Wei Yang 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/sparse: abstract sparse buffer allocations

2018-08-17T23:20:32+00:00

Patch series "sparse_init rewrite", v6.

In sparse_init() we allocate two large buffers to temporary hold usemap
and memmap for the whole machine.  However, we can avoid doing that if
we changed sparse_init() to operated on per-node bases instead of doing
it on the whole machine beforehand.

As shown by Baoquan
  http://lkml.kernel.org/r/20180628062857.29658-1-bhe@redhat.com

The buffers are large enough to cause machine stop to boot on small
memory systems.

Another benefit of these changes is that they also obsolete
CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER.

This patch (of 5):

When struct pages are allocated for sparse-vmemmap VA layout, we first try
to allocate one large buffer, and than if that fails allocate struct pages
for each section as we go.

The code that allocates buffer is uses global variables and is spread
across several call sites.

Cleanup the code by introducing three functions to handle the global
buffer:

sparse_buffer_init()	initialize the buffer
sparse_buffer_fini()	free the remaining part of the buffer
sparse_buffer_alloc()	alloc from the buffer, and if buffer is empty
return NULL

Define these functions in sparse.c instead of sparse-vmemmap.c because
later we will use them for non-vmemmap sparse allocations as well.

[akpm@linux-foundation.org: use PTR_ALIGN()]
[akpm@linux-foundation.org: s/BUG_ON/WARN_ON/]
Link: http://lkml.kernel.org/r/20180712203730.8703-2-pasha.tatashin@oracle.com
Signed-off-by: Pavel Tatashin 
Tested-by: Michael Ellerman 	[powerpc]
Reviewed-by: Oscar Salvador 
Tested-by: Oscar Salvador 
Cc: Pasha Tatashin 
Cc: Steven Sistare 
Cc: Daniel Jordan 
Cc: "Kirill A. Shutemov" 
Cc: Michal Hocko 
Cc: Dan Williams 
Cc: Jan Kara 
Cc: Jérôme Glisse 
Cc: Souptick Joarder 
Cc: Baoquan He 
Cc: Greg Kroah-Hartman 
Cc: Vlastimil Babka 
Cc: Wei Yang 
Cc: Dave Hansen 
Cc: David Rientjes 
Cc: Ingo Molnar 
Cc: Abdul Haleem 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/sparse: optimize memmap allocation during sparse_init()

2018-08-17T23:20:31+00:00

In sparse_init(), two temporary pointer arrays, usemap_map and map_map
are allocated with the size of NR_MEM_SECTIONS.  They are used to store
each memory section's usemap and mem map if marked as present.  With the
help of these two arrays, continuous memory chunk is allocated for
usemap and memmap for memory sections on one node.  This avoids too many
memory fragmentations.  Like below diagram, '1' indicates the present
memory section, '0' means absent one.  The number 'n' could be much
smaller than NR_MEM_SECTIONS on most of systems.

  |1|1|1|1|0|0|0|0|1|1|0|0|...|1|0||1|0|...|1||0|1|...|0|
  -------------------------------------------------------
   0 1 2 3         4 5         i   i+1     n-1   n

If we fail to populate the page tables to map one section's memmap, its
->section_mem_map will be cleared finally to indicate that it's not
present.  After use, these two arrays will be released at the end of
sparse_init().

In 4-level paging mode, each array costs 4M which can be ignorable.
While in 5-level paging, they costs 256M each, 512M altogether.  Kdump
kernel Usually only reserves very few memory, e.g 256M.  So, even thouth
they are temporarily allocated, still not acceptable.

In fact, there's no need to allocate them with the size of
NR_MEM_SECTIONS.  Since the ->section_mem_map clearing has been deferred
to the last, the number of present memory sections are kept the same
during sparse_init() until we finally clear out the memory section's
->section_mem_map if its usemap or memmap is not correctly handled.
Thus in the middle whenever for_each_present_section_nr() loop is taken,
the i-th present memory section is always the same one.

Here only allocate usemap_map and map_map with the size of
'nr_present_sections'.  For the i-th present memory section, install its
usemap and memmap to usemap_map[i] and mam_map[i] during allocation.
Then in the last for_each_present_section_nr() loop which clears the
failed memory section's ->section_mem_map, fetch usemap and memmap from
usemap_map[] and map_map[] array and set them into mem_section[]
accordingly.

[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/20180628062857.29658-5-bhe@redhat.com
Signed-off-by: Baoquan He 
Reviewed-by: Pavel Tatashin 
Cc: Pasha Tatashin 
Cc: Dave Hansen 
Cc: Kirill A. Shutemov 
Cc: Oscar Salvador 
Cc: Pankaj Gupta 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/sparse.c: add a new parameter 'data_unit_size' for alloc_usemap_and_memmap

2018-08-17T23:20:31+00:00

It's used to pass the size of map data unit into
alloc_usemap_and_memmap, and is preparation for next patch.

Link: http://lkml.kernel.org/r/20180228032657.32385-4-bhe@redhat.com
Signed-off-by: Baoquan He 
Reviewed-by: Pavel Tatashin 
Reviewed-by: Oscar Salvador 
Cc: Pasha Tatashin 
Cc: Kirill A. Shutemov 
Cc: Pankaj Gupta 
Cc: Dave Hansen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/sparsemem.c: defer the ms->section_mem_map clearing

2018-08-17T23:20:31+00:00

In sparse_init(), if CONFIG_SPARSEMEM_ALLOC_MEM_MAP_TOGETHER=y, system
will allocate one continuous memory chunk for mem maps on one node and
populate the relevant page tables to map memory section one by one.  If
fail to populate for a certain mem section, print warning and its
->section_mem_map will be cleared to cancel the marking of being
present.  Like this, the number of mem sections marked as present could
become less during sparse_init() execution.

Here just defer the ms->section_mem_map clearing if failed to populate
its page tables until the last for_each_present_section_nr() loop.  This
is in preparation for later optimizing the mem map allocation.

[akpm@linux-foundation.org: remove now-unused local `ms', per Oscar]
Link: http://lkml.kernel.org/r/20180228032657.32385-3-bhe@redhat.com
Signed-off-by: Baoquan He 
Acked-by: Dave Hansen 
Reviewed-by: Pavel Tatashin 
Reviewed-by: Oscar Salvador 
Cc: Pasha Tatashin 
Cc: Kirill A. Shutemov 
Cc: Pankaj Gupta 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/sparse.c: add a static variable nr_present_sections

2018-08-17T23:20:31+00:00

Patch series "mm/sparse: Optimize memmap allocation during
sparse_init()", v6.

In sparse_init(), two temporary pointer arrays, usemap_map and map_map
are allocated with the size of NR_MEM_SECTIONS.  They are used to store
each memory section's usemap and mem map if marked as present.  In
5-level paging mode, this will cost 512M memory though they will be
released at the end of sparse_init().  System with few memory, like
kdump kernel which usually only has about 256M, will fail to boot
because of allocation failure if CONFIG_X86_5LEVEL=y.

In this patchset, optimize the memmap allocation code to only use
usemap_map and map_map with the size of nr_present_sections.  This makes
kdump kernel boot up with normal crashkernel='' setting when
CONFIG_X86_5LEVEL=y.

This patch (of 5):

nr_present_sections is used to record how many memory sections are
marked as present during system boot up, and will be used in the later
patch.

Link: http://lkml.kernel.org/r/20180228032657.32385-2-bhe@redhat.com
Signed-off-by: Baoquan He 
Acked-by: Dave Hansen 
Reviewed-by: Andrew Morton 
Reviewed-by: Pavel Tatashin 
Reviewed-by: Oscar Salvador 
Cc: Pasha Tatashin 
Cc: Kirill A. Shutemov 
Cc: Pankaj Gupta 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/sparse.c: make sparse_init_one_section void and remove check

2018-08-17T23:20:30+00:00

sparse_init_one_section() is being called from two sites: sparse_init()
and sparse_add_one_section().  The former calls it from a
for_each_present_section_nr() loop, and the latter marks the section as
present before calling it.  This means that when
sparse_init_one_section() gets called, we already know that the section
is present.  So there is no point to double check that in the function.

This removes the check and makes the function void.

[ross.zwisler@linux.intel.com: fix error path in sparse_add_one_section]
  Link: http://lkml.kernel.org/r/20180706190658.6873-1-ross.zwisler@linux.intel.com
[ross.zwisler@linux.intel.com: simplification suggested by Oscar]
  Link: http://lkml.kernel.org/r/20180706223358.742-1-ross.zwisler@linux.intel.com
Link: http://lkml.kernel.org/r/20180702154325.12196-1-osalvador@techadventures.net
Signed-off-by: Oscar Salvador 
Acked-by: Michal Hocko 
Reviewed-by: Pavel Tatashin 
Reviewed-by: Andrew Morton 
Cc: Pasha Tatashin 
Cc: Oscar Salvador 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds