<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/mm/sparse.c, branch v5.13.2</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>mm/sparse: fix check_usemap_section_nr warnings</title>
<updated>2021-06-16T16:24:43+00:00</updated>
<author>
<name>Miles Chen</name>
<email>miles.chen@mediatek.com</email>
</author>
<published>2021-06-16T01:24:10+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=ccbd6283a9b640c8d5c2b44db318fd72a63338ff'/>
<id>ccbd6283a9b640c8d5c2b44db318fd72a63338ff</id>
<content type='text'>
I see a "virt_to_phys used for non-linear address" warning from
check_usemap_section_nr() on arm64 platforms.

In current implementation of NODE_DATA, if CONFIG_NEED_MULTIPLE_NODES=y,
pglist_data is dynamically allocated and assigned to node_data[].

For example, in arch/arm64/include/asm/mmzone.h:

  extern struct pglist_data *node_data[];
  #define NODE_DATA(nid)          (node_data[(nid)])

If CONFIG_NEED_MULTIPLE_NODES=n, pglist_data is defined as a global
variable named "contig_page_data".

For example, in include/linux/mmzone.h:

  extern struct pglist_data contig_page_data;
  #define NODE_DATA(nid)          (&amp;contig_page_data)

If CONFIG_DEBUG_VIRTUAL is not enabled, __pa() can handle both
dynamically allocated linear addresses and symbol addresses.  However,
if (CONFIG_DEBUG_VIRTUAL=y &amp;&amp; CONFIG_NEED_MULTIPLE_NODES=n) we can see
the "virt_to_phys used for non-linear address" warning because that
&amp;contig_page_data is not a linear address on arm64.

Warning message:

  virt_to_phys used for non-linear address: (contig_page_data+0x0/0x1c00)
  WARNING: CPU: 0 PID: 0 at arch/arm64/mm/physaddr.c:15 __virt_to_phys+0x58/0x68
  Modules linked in:
  CPU: 0 PID: 0 Comm: swapper Tainted: G        W         5.13.0-rc1-00074-g1140ab592e2e #3
  Hardware name: linux,dummy-virt (DT)
  pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO BTYPE=--)
  Call trace:
     __virt_to_phys+0x58/0x68
     check_usemap_section_nr+0x50/0xfc
     sparse_init_nid+0x1ac/0x28c
     sparse_init+0x1c4/0x1e0
     bootmem_init+0x60/0x90
     setup_arch+0x184/0x1f0
     start_kernel+0x78/0x488

To fix it, create a small function to handle both translation.

Link: https://lkml.kernel.org/r/1623058729-27264-1-git-send-email-miles.chen@mediatek.com
Signed-off-by: Miles Chen &lt;miles.chen@mediatek.com&gt;
Cc: Mike Rapoport &lt;rppt@kernel.org&gt;
Cc: Baoquan He &lt;bhe@redhat.com&gt;
Cc: Kazu &lt;k-hagio-ab@nec.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
I see a "virt_to_phys used for non-linear address" warning from
check_usemap_section_nr() on arm64 platforms.

In current implementation of NODE_DATA, if CONFIG_NEED_MULTIPLE_NODES=y,
pglist_data is dynamically allocated and assigned to node_data[].

For example, in arch/arm64/include/asm/mmzone.h:

  extern struct pglist_data *node_data[];
  #define NODE_DATA(nid)          (node_data[(nid)])

If CONFIG_NEED_MULTIPLE_NODES=n, pglist_data is defined as a global
variable named "contig_page_data".

For example, in include/linux/mmzone.h:

  extern struct pglist_data contig_page_data;
  #define NODE_DATA(nid)          (&amp;contig_page_data)

If CONFIG_DEBUG_VIRTUAL is not enabled, __pa() can handle both
dynamically allocated linear addresses and symbol addresses.  However,
if (CONFIG_DEBUG_VIRTUAL=y &amp;&amp; CONFIG_NEED_MULTIPLE_NODES=n) we can see
the "virt_to_phys used for non-linear address" warning because that
&amp;contig_page_data is not a linear address on arm64.

Warning message:

  virt_to_phys used for non-linear address: (contig_page_data+0x0/0x1c00)
  WARNING: CPU: 0 PID: 0 at arch/arm64/mm/physaddr.c:15 __virt_to_phys+0x58/0x68
  Modules linked in:
  CPU: 0 PID: 0 Comm: swapper Tainted: G        W         5.13.0-rc1-00074-g1140ab592e2e #3
  Hardware name: linux,dummy-virt (DT)
  pstate: 600000c5 (nZCv daIF -PAN -UAO -TCO BTYPE=--)
  Call trace:
     __virt_to_phys+0x58/0x68
     check_usemap_section_nr+0x50/0xfc
     sparse_init_nid+0x1ac/0x28c
     sparse_init+0x1c4/0x1e0
     bootmem_init+0x60/0x90
     setup_arch+0x184/0x1f0
     start_kernel+0x78/0x488

To fix it, create a small function to handle both translation.

Link: https://lkml.kernel.org/r/1623058729-27264-1-git-send-email-miles.chen@mediatek.com
Signed-off-by: Miles Chen &lt;miles.chen@mediatek.com&gt;
Cc: Mike Rapoport &lt;rppt@kernel.org&gt;
Cc: Baoquan He &lt;bhe@redhat.com&gt;
Cc: Kazu &lt;k-hagio-ab@nec.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm/mempool: minor coding style tweaks</title>
<updated>2021-05-05T18:27:27+00:00</updated>
<author>
<name>Zhiyuan Dai</name>
<email>daizhiyuan@phytium.com.cn</email>
</author>
<published>2021-05-05T01:40:12+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=68d68ff6ebbf69d02511dd48f16b3795671c9b0b'/>
<id>68d68ff6ebbf69d02511dd48f16b3795671c9b0b</id>
<content type='text'>
Various coding style tweaks to various files under mm/

[daizhiyuan@phytium.com.cn: mm/swapfile: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1614223624-16055-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/sparse: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1614227288-19363-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/vmscan: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1614227649-19853-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/compaction: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1614228218-20770-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/oom_kill: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1614228360-21168-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/shmem: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1614228504-21491-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/page_alloc: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1614228613-21754-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/filemap: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1614228936-22337-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/mlock: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1613956588-2453-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/frontswap: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1613962668-15045-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/vmalloc: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1613963379-15988-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/memory_hotplug: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1613971784-24878-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/mempolicy: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1613972228-25501-1-git-send-email-daizhiyuan@phytium.com.cn

Link: https://lkml.kernel.org/r/1614222374-13805-1-git-send-email-daizhiyuan@phytium.com.cn
Signed-off-by: Zhiyuan Dai &lt;daizhiyuan@phytium.com.cn&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Various coding style tweaks to various files under mm/

[daizhiyuan@phytium.com.cn: mm/swapfile: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1614223624-16055-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/sparse: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1614227288-19363-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/vmscan: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1614227649-19853-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/compaction: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1614228218-20770-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/oom_kill: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1614228360-21168-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/shmem: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1614228504-21491-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/page_alloc: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1614228613-21754-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/filemap: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1614228936-22337-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/mlock: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1613956588-2453-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/frontswap: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1613962668-15045-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/vmalloc: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1613963379-15988-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/memory_hotplug: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1613971784-24878-1-git-send-email-daizhiyuan@phytium.com.cn
[daizhiyuan@phytium.com.cn: mm/mempolicy: minor coding style tweaks]
  Link: https://lkml.kernel.org/r/1613972228-25501-1-git-send-email-daizhiyuan@phytium.com.cn

Link: https://lkml.kernel.org/r/1614222374-13805-1-git-send-email-daizhiyuan@phytium.com.cn
Signed-off-by: Zhiyuan Dai &lt;daizhiyuan@phytium.com.cn&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm,memory_hotplug: allocate memmap from the added memory range</title>
<updated>2021-05-05T18:27:26+00:00</updated>
<author>
<name>Oscar Salvador</name>
<email>osalvador@suse.de</email>
</author>
<published>2021-05-05T01:39:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=a08a2ae3461383c2d50d0997dcc6cd1dd1fefb08'/>
<id>a08a2ae3461383c2d50d0997dcc6cd1dd1fefb08</id>
<content type='text'>
Physical memory hotadd has to allocate a memmap (struct page array) for
the newly added memory section.  Currently, alloc_pages_node() is used
for those allocations.

This has some disadvantages:
 a) an existing memory is consumed for that purpose
    (eg: ~2MB per 128MB memory section on x86_64)
    This can even lead to extreme cases where system goes OOM because
    the physically hotplugged memory depletes the available memory before
    it is onlined.
 b) if the whole node is movable then we have off-node struct pages
    which has performance drawbacks.
 c) It might be there are no PMD_ALIGNED chunks so memmap array gets
    populated with base pages.

This can be improved when CONFIG_SPARSEMEM_VMEMMAP is enabled.

Vmemap page tables can map arbitrary memory.  That means that we can
reserve a part of the physically hotadded memory to back vmemmap page
tables.  This implementation uses the beginning of the hotplugged memory
for that purpose.

There are some non-obviously things to consider though.

Vmemmap pages are allocated/freed during the memory hotplug events
(add_memory_resource(), try_remove_memory()) when the memory is
added/removed.  This means that the reserved physical range is not
online although it is used.  The most obvious side effect is that
pfn_to_online_page() returns NULL for those pfns.  The current design
expects that this should be OK as the hotplugged memory is considered a
garbage until it is onlined.  For example hibernation wouldn't save the
content of those vmmemmaps into the image so it wouldn't be restored on
resume but this should be OK as there no real content to recover anyway
while metadata is reachable from other data structures (e.g.  vmemmap
page tables).

The reserved space is therefore (de)initialized during the {on,off}line
events (mhp_{de}init_memmap_on_memory).  That is done by extracting page
allocator independent initialization from the regular onlining path.
The primary reason to handle the reserved space outside of
{on,off}line_pages is to make each initialization specific to the
purpose rather than special case them in a single function.

As per above, the functions that are introduced are:

 - mhp_init_memmap_on_memory:
   Initializes vmemmap pages by calling move_pfn_range_to_zone(), calls
   kasan_add_zero_shadow(), and onlines as many sections as vmemmap pages
   fully span.

 - mhp_deinit_memmap_on_memory:
   Offlines as many sections as vmemmap pages fully span, removes the
   range from zhe zone by remove_pfn_range_from_zone(), and calls
   kasan_remove_zero_shadow() for the range.

The new function memory_block_online() calls mhp_init_memmap_on_memory()
before doing the actual online_pages().  Should online_pages() fail, we
clean up by calling mhp_deinit_memmap_on_memory().  Adjusting of
present_pages is done at the end once we know that online_pages()
succedeed.

On offline, memory_block_offline() needs to unaccount vmemmap pages from
present_pages() before calling offline_pages().  This is necessary because
offline_pages() tears down some structures based on the fact whether the
node or the zone become empty.  If offline_pages() fails, we account back
vmemmap pages.  If it succeeds, we call mhp_deinit_memmap_on_memory().

Hot-remove:

 We need to be careful when removing memory, as adding and
 removing memory needs to be done with the same granularity.
 To check that this assumption is not violated, we check the
 memory range we want to remove and if a) any memory block has
 vmemmap pages and b) the range spans more than a single memory
 block, we scream out loud and refuse to proceed.

 If all is good and the range was using memmap on memory (aka vmemmap pages),
 we construct an altmap structure so free_hugepage_table does the right
 thing and calls vmem_altmap_free instead of free_pagetable.

Link: https://lkml.kernel.org/r/20210421102701.25051-5-osalvador@suse.de
Signed-off-by: Oscar Salvador &lt;osalvador@suse.de&gt;
Reviewed-by: David Hildenbrand &lt;david@redhat.com&gt;
Acked-by: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: Anshuman Khandual &lt;anshuman.khandual@arm.com&gt;
Cc: Pavel Tatashin &lt;pasha.tatashin@soleen.com&gt;
Cc: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Physical memory hotadd has to allocate a memmap (struct page array) for
the newly added memory section.  Currently, alloc_pages_node() is used
for those allocations.

This has some disadvantages:
 a) an existing memory is consumed for that purpose
    (eg: ~2MB per 128MB memory section on x86_64)
    This can even lead to extreme cases where system goes OOM because
    the physically hotplugged memory depletes the available memory before
    it is onlined.
 b) if the whole node is movable then we have off-node struct pages
    which has performance drawbacks.
 c) It might be there are no PMD_ALIGNED chunks so memmap array gets
    populated with base pages.

This can be improved when CONFIG_SPARSEMEM_VMEMMAP is enabled.

Vmemap page tables can map arbitrary memory.  That means that we can
reserve a part of the physically hotadded memory to back vmemmap page
tables.  This implementation uses the beginning of the hotplugged memory
for that purpose.

There are some non-obviously things to consider though.

Vmemmap pages are allocated/freed during the memory hotplug events
(add_memory_resource(), try_remove_memory()) when the memory is
added/removed.  This means that the reserved physical range is not
online although it is used.  The most obvious side effect is that
pfn_to_online_page() returns NULL for those pfns.  The current design
expects that this should be OK as the hotplugged memory is considered a
garbage until it is onlined.  For example hibernation wouldn't save the
content of those vmmemmaps into the image so it wouldn't be restored on
resume but this should be OK as there no real content to recover anyway
while metadata is reachable from other data structures (e.g.  vmemmap
page tables).

The reserved space is therefore (de)initialized during the {on,off}line
events (mhp_{de}init_memmap_on_memory).  That is done by extracting page
allocator independent initialization from the regular onlining path.
The primary reason to handle the reserved space outside of
{on,off}line_pages is to make each initialization specific to the
purpose rather than special case them in a single function.

As per above, the functions that are introduced are:

 - mhp_init_memmap_on_memory:
   Initializes vmemmap pages by calling move_pfn_range_to_zone(), calls
   kasan_add_zero_shadow(), and onlines as many sections as vmemmap pages
   fully span.

 - mhp_deinit_memmap_on_memory:
   Offlines as many sections as vmemmap pages fully span, removes the
   range from zhe zone by remove_pfn_range_from_zone(), and calls
   kasan_remove_zero_shadow() for the range.

The new function memory_block_online() calls mhp_init_memmap_on_memory()
before doing the actual online_pages().  Should online_pages() fail, we
clean up by calling mhp_deinit_memmap_on_memory().  Adjusting of
present_pages is done at the end once we know that online_pages()
succedeed.

On offline, memory_block_offline() needs to unaccount vmemmap pages from
present_pages() before calling offline_pages().  This is necessary because
offline_pages() tears down some structures based on the fact whether the
node or the zone become empty.  If offline_pages() fails, we account back
vmemmap pages.  If it succeeds, we call mhp_deinit_memmap_on_memory().

Hot-remove:

 We need to be careful when removing memory, as adding and
 removing memory needs to be done with the same granularity.
 To check that this assumption is not violated, we check the
 memory range we want to remove and if a) any memory block has
 vmemmap pages and b) the range spans more than a single memory
 block, we scream out loud and refuse to proceed.

 If all is good and the range was using memmap on memory (aka vmemmap pages),
 we construct an altmap structure so free_hugepage_table does the right
 thing and calls vmem_altmap_free instead of free_pagetable.

Link: https://lkml.kernel.org/r/20210421102701.25051-5-osalvador@suse.de
Signed-off-by: Oscar Salvador &lt;osalvador@suse.de&gt;
Reviewed-by: David Hildenbrand &lt;david@redhat.com&gt;
Acked-by: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: Anshuman Khandual &lt;anshuman.khandual@arm.com&gt;
Cc: Pavel Tatashin &lt;pasha.tatashin@soleen.com&gt;
Cc: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm/sparse: add the missing sparse_buffer_fini() in error branch</title>
<updated>2021-04-30T18:20:39+00:00</updated>
<author>
<name>Wang Wensheng</name>
<email>wangwensheng4@huawei.com</email>
</author>
<published>2021-04-30T05:57:58+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=2284f47fe9fe2ed2ef619e5474e155cfeeebd569'/>
<id>2284f47fe9fe2ed2ef619e5474e155cfeeebd569</id>
<content type='text'>
sparse_buffer_init() and sparse_buffer_fini() should appear in pair, or a
WARN issue would be through the next time sparse_buffer_init() runs.

Add the missing sparse_buffer_fini() in error branch.

Link: https://lkml.kernel.org/r/20210325113155.118574-1-wangwensheng4@huawei.com
Fixes: 85c77f791390 ("mm/sparse: add new sparse_init_nid() and sparse_init()")
Signed-off-by: Wang Wensheng &lt;wangwensheng4@huawei.com&gt;
Reviewed-by: David Hildenbrand &lt;david@redhat.com&gt;
Reviewed-by: Oscar Salvador &lt;osalvador@suse.de&gt;
Cc: Pavel Tatashin &lt;pasha.tatashin@oracle.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
sparse_buffer_init() and sparse_buffer_fini() should appear in pair, or a
WARN issue would be through the next time sparse_buffer_init() runs.

Add the missing sparse_buffer_fini() in error branch.

Link: https://lkml.kernel.org/r/20210325113155.118574-1-wangwensheng4@huawei.com
Fixes: 85c77f791390 ("mm/sparse: add new sparse_init_nid() and sparse_init()")
Signed-off-by: Wang Wensheng &lt;wangwensheng4@huawei.com&gt;
Reviewed-by: David Hildenbrand &lt;david@redhat.com&gt;
Reviewed-by: Oscar Salvador &lt;osalvador@suse.de&gt;
Cc: Pavel Tatashin &lt;pasha.tatashin@oracle.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm/memory_hotplug: guard more declarations by CONFIG_MEMORY_HOTPLUG</title>
<updated>2020-10-16T18:11:18+00:00</updated>
<author>
<name>David Hildenbrand</name>
<email>david@redhat.com</email>
</author>
<published>2020-10-16T03:08:39+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=3a0aaefe4134951b4e89feb873c457428154530c'/>
<id>3a0aaefe4134951b4e89feb873c457428154530c</id>
<content type='text'>
We soon want to pass flags via a new type to add_memory() and friends.
That revealed that we currently don't guard some declarations by
CONFIG_MEMORY_HOTPLUG.

While some definitions could be moved to different places, let's keep it
minimal for now and use CONFIG_MEMORY_HOTPLUG for all functions only
compiled with CONFIG_MEMORY_HOTPLUG.

Wrap sparse_decode_mem_map() into CONFIG_MEMORY_HOTPLUG, it's only called
from CONFIG_MEMORY_HOTPLUG code.

While at it, remove allow_online_pfn_range(), which is no longer around,
and mhp_notimplemented(), which is unused.

Signed-off-by: David Hildenbrand &lt;david@redhat.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: Dan Williams &lt;dan.j.williams@intel.com&gt;
Cc: Pankaj Gupta &lt;pankaj.gupta.linux@gmail.com&gt;
Cc: Baoquan He &lt;bhe@redhat.com&gt;
Cc: Wei Yang &lt;richardw.yang@linux.intel.com&gt;
Cc: Anton Blanchard &lt;anton@ozlabs.org&gt;
Cc: Ard Biesheuvel &lt;ardb@kernel.org&gt;
Cc: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Cc: Boris Ostrovsky &lt;boris.ostrovsky@oracle.com&gt;
Cc: Christian Borntraeger &lt;borntraeger@de.ibm.com&gt;
Cc: Dave Jiang &lt;dave.jiang@intel.com&gt;
Cc: Eric Biederman &lt;ebiederm@xmission.com&gt;
Cc: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Cc: Haiyang Zhang &lt;haiyangz@microsoft.com&gt;
Cc: Heiko Carstens &lt;hca@linux.ibm.com&gt;
Cc: Jason Gunthorpe &lt;jgg@ziepe.ca&gt;
Cc: Jason Wang &lt;jasowang@redhat.com&gt;
Cc: Juergen Gross &lt;jgross@suse.com&gt;
Cc: Julien Grall &lt;julien@xen.org&gt;
Cc: Kees Cook &lt;keescook@chromium.org&gt;
Cc: "K. Y. Srinivasan" &lt;kys@microsoft.com&gt;
Cc: Len Brown &lt;lenb@kernel.org&gt;
Cc: Leonardo Bras &lt;leobras.c@gmail.com&gt;
Cc: Libor Pechacek &lt;lpechacek@suse.cz&gt;
Cc: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Cc: "Michael S. Tsirkin" &lt;mst@redhat.com&gt;
Cc: Nathan Lynch &lt;nathanl@linux.ibm.com&gt;
Cc: "Oliver O'Halloran" &lt;oohall@gmail.com&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Pingfan Liu &lt;kernelfans@gmail.com&gt;
Cc: "Rafael J. Wysocki" &lt;rjw@rjwysocki.net&gt;
Cc: Roger Pau Monné &lt;roger.pau@citrix.com&gt;
Cc: Stefano Stabellini &lt;sstabellini@kernel.org&gt;
Cc: Stephen Hemminger &lt;sthemmin@microsoft.com&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Vasily Gorbik &lt;gor@linux.ibm.com&gt;
Cc: Vishal Verma &lt;vishal.l.verma@intel.com&gt;
Cc: Wei Liu &lt;wei.liu@kernel.org&gt;
Link: https://lkml.kernel.org/r/20200911103459.10306-4-david@redhat.com
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
We soon want to pass flags via a new type to add_memory() and friends.
That revealed that we currently don't guard some declarations by
CONFIG_MEMORY_HOTPLUG.

While some definitions could be moved to different places, let's keep it
minimal for now and use CONFIG_MEMORY_HOTPLUG for all functions only
compiled with CONFIG_MEMORY_HOTPLUG.

Wrap sparse_decode_mem_map() into CONFIG_MEMORY_HOTPLUG, it's only called
from CONFIG_MEMORY_HOTPLUG code.

While at it, remove allow_online_pfn_range(), which is no longer around,
and mhp_notimplemented(), which is unused.

Signed-off-by: David Hildenbrand &lt;david@redhat.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Michal Hocko &lt;mhocko@suse.com&gt;
Cc: Dan Williams &lt;dan.j.williams@intel.com&gt;
Cc: Pankaj Gupta &lt;pankaj.gupta.linux@gmail.com&gt;
Cc: Baoquan He &lt;bhe@redhat.com&gt;
Cc: Wei Yang &lt;richardw.yang@linux.intel.com&gt;
Cc: Anton Blanchard &lt;anton@ozlabs.org&gt;
Cc: Ard Biesheuvel &lt;ardb@kernel.org&gt;
Cc: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Cc: Boris Ostrovsky &lt;boris.ostrovsky@oracle.com&gt;
Cc: Christian Borntraeger &lt;borntraeger@de.ibm.com&gt;
Cc: Dave Jiang &lt;dave.jiang@intel.com&gt;
Cc: Eric Biederman &lt;ebiederm@xmission.com&gt;
Cc: Greg Kroah-Hartman &lt;gregkh@linuxfoundation.org&gt;
Cc: Haiyang Zhang &lt;haiyangz@microsoft.com&gt;
Cc: Heiko Carstens &lt;hca@linux.ibm.com&gt;
Cc: Jason Gunthorpe &lt;jgg@ziepe.ca&gt;
Cc: Jason Wang &lt;jasowang@redhat.com&gt;
Cc: Juergen Gross &lt;jgross@suse.com&gt;
Cc: Julien Grall &lt;julien@xen.org&gt;
Cc: Kees Cook &lt;keescook@chromium.org&gt;
Cc: "K. Y. Srinivasan" &lt;kys@microsoft.com&gt;
Cc: Len Brown &lt;lenb@kernel.org&gt;
Cc: Leonardo Bras &lt;leobras.c@gmail.com&gt;
Cc: Libor Pechacek &lt;lpechacek@suse.cz&gt;
Cc: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Cc: "Michael S. Tsirkin" &lt;mst@redhat.com&gt;
Cc: Nathan Lynch &lt;nathanl@linux.ibm.com&gt;
Cc: "Oliver O'Halloran" &lt;oohall@gmail.com&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Pingfan Liu &lt;kernelfans@gmail.com&gt;
Cc: "Rafael J. Wysocki" &lt;rjw@rjwysocki.net&gt;
Cc: Roger Pau Monné &lt;roger.pau@citrix.com&gt;
Cc: Stefano Stabellini &lt;sstabellini@kernel.org&gt;
Cc: Stephen Hemminger &lt;sthemmin@microsoft.com&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Vasily Gorbik &lt;gor@linux.ibm.com&gt;
Cc: Vishal Verma &lt;vishal.l.verma@intel.com&gt;
Cc: Wei Liu &lt;wei.liu@kernel.org&gt;
Link: https://lkml.kernel.org/r/20200911103459.10306-4-david@redhat.com
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>arch, mm: replace for_each_memblock() with for_each_mem_pfn_range()</title>
<updated>2020-10-14T01:38:35+00:00</updated>
<author>
<name>Mike Rapoport</name>
<email>rppt@linux.ibm.com</email>
</author>
<published>2020-10-13T23:58:03+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c9118e6c37bff9ade90b638207a6e0db676ee6a9'/>
<id>c9118e6c37bff9ade90b638207a6e0db676ee6a9</id>
<content type='text'>
There are several occurrences of the following pattern:

	for_each_memblock(memory, reg) {
		start_pfn = memblock_region_memory_base_pfn(reg);
		end_pfn = memblock_region_memory_end_pfn(reg);

		/* do something with start_pfn and end_pfn */
	}

Rather than iterate over all memblock.memory regions and each time query
for their start and end PFNs, use for_each_mem_pfn_range() iterator to get
simpler and clearer code.

Signed-off-by: Mike Rapoport &lt;rppt@linux.ibm.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Reviewed-by: Baoquan He &lt;bhe@redhat.com&gt;
Acked-by: Miguel Ojeda &lt;miguel.ojeda.sandonis@gmail.com&gt;	[.clang-format]
Cc: Andy Lutomirski &lt;luto@kernel.org&gt;
Cc: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Cc: Borislav Petkov &lt;bp@alien8.de&gt;
Cc: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Cc: Christoph Hellwig &lt;hch@lst.de&gt;
Cc: Daniel Axtens &lt;dja@axtens.net&gt;
Cc: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
Cc: Emil Renner Berthing &lt;kernel@esmil.dk&gt;
Cc: Hari Bathini &lt;hbathini@linux.ibm.com&gt;
Cc: Ingo Molnar &lt;mingo@kernel.org&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
Cc: Marek Szyprowski &lt;m.szyprowski@samsung.com&gt;
Cc: Max Filippov &lt;jcmvbkbc@gmail.com&gt;
Cc: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Cc: Michal Simek &lt;monstr@monstr.eu&gt;
Cc: Palmer Dabbelt &lt;palmer@dabbelt.com&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Paul Walmsley &lt;paul.walmsley@sifive.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Russell King &lt;linux@armlinux.org.uk&gt;
Cc: Stafford Horne &lt;shorne@gmail.com&gt;
Cc: Thomas Bogendoerfer &lt;tsbogend@alpha.franken.de&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Will Deacon &lt;will@kernel.org&gt;
Cc: Yoshinori Sato &lt;ysato@users.sourceforge.jp&gt;
Link: https://lkml.kernel.org/r/20200818151634.14343-12-rppt@kernel.org
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
There are several occurrences of the following pattern:

	for_each_memblock(memory, reg) {
		start_pfn = memblock_region_memory_base_pfn(reg);
		end_pfn = memblock_region_memory_end_pfn(reg);

		/* do something with start_pfn and end_pfn */
	}

Rather than iterate over all memblock.memory regions and each time query
for their start and end PFNs, use for_each_mem_pfn_range() iterator to get
simpler and clearer code.

Signed-off-by: Mike Rapoport &lt;rppt@linux.ibm.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Reviewed-by: Baoquan He &lt;bhe@redhat.com&gt;
Acked-by: Miguel Ojeda &lt;miguel.ojeda.sandonis@gmail.com&gt;	[.clang-format]
Cc: Andy Lutomirski &lt;luto@kernel.org&gt;
Cc: Benjamin Herrenschmidt &lt;benh@kernel.crashing.org&gt;
Cc: Borislav Petkov &lt;bp@alien8.de&gt;
Cc: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Cc: Christoph Hellwig &lt;hch@lst.de&gt;
Cc: Daniel Axtens &lt;dja@axtens.net&gt;
Cc: Dave Hansen &lt;dave.hansen@linux.intel.com&gt;
Cc: Emil Renner Berthing &lt;kernel@esmil.dk&gt;
Cc: Hari Bathini &lt;hbathini@linux.ibm.com&gt;
Cc: Ingo Molnar &lt;mingo@kernel.org&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Jonathan Cameron &lt;Jonathan.Cameron@huawei.com&gt;
Cc: Marek Szyprowski &lt;m.szyprowski@samsung.com&gt;
Cc: Max Filippov &lt;jcmvbkbc@gmail.com&gt;
Cc: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Cc: Michal Simek &lt;monstr@monstr.eu&gt;
Cc: Palmer Dabbelt &lt;palmer@dabbelt.com&gt;
Cc: Paul Mackerras &lt;paulus@samba.org&gt;
Cc: Paul Walmsley &lt;paul.walmsley@sifive.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Russell King &lt;linux@armlinux.org.uk&gt;
Cc: Stafford Horne &lt;shorne@gmail.com&gt;
Cc: Thomas Bogendoerfer &lt;tsbogend@alpha.franken.de&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Will Deacon &lt;will@kernel.org&gt;
Cc: Yoshinori Sato &lt;ysato@users.sourceforge.jp&gt;
Link: https://lkml.kernel.org/r/20200818151634.14343-12-rppt@kernel.org
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm/sparse: cleanup the code surrounding memory_present()</title>
<updated>2020-08-07T18:33:27+00:00</updated>
<author>
<name>Mike Rapoport</name>
<email>rppt@linux.ibm.com</email>
</author>
<published>2020-08-07T06:24:02+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=c89ab04febf97d2db8ca4ef8e2866fadc474351b'/>
<id>c89ab04febf97d2db8ca4ef8e2866fadc474351b</id>
<content type='text'>
After removal of CONFIG_HAVE_MEMBLOCK_NODE_MAP we have two equivalent
functions that call memory_present() for each region in memblock.memory:
sparse_memory_present_with_active_regions() and membocks_present().

Moreover, all architectures have a call to either of these functions
preceding the call to sparse_init() and in the most cases they are called
one after the other.

Mark the regions from memblock.memory as present during sparce_init() by
making sparse_init() call memblocks_present(), make memblocks_present()
and memory_present() functions static and remove redundant
sparse_memory_present_with_active_regions() function.

Also remove no longer required HAVE_MEMORY_PRESENT configuration option.

Signed-off-by: Mike Rapoport &lt;rppt@linux.ibm.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Link: http://lkml.kernel.org/r/20200712083130.22919-1-rppt@kernel.org
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
After removal of CONFIG_HAVE_MEMBLOCK_NODE_MAP we have two equivalent
functions that call memory_present() for each region in memblock.memory:
sparse_memory_present_with_active_regions() and membocks_present().

Moreover, all architectures have a call to either of these functions
preceding the call to sparse_init() and in the most cases they are called
one after the other.

Mark the regions from memblock.memory as present during sparce_init() by
making sparse_init() call memblocks_present(), make memblocks_present()
and memory_present() functions static and remove redundant
sparse_memory_present_with_active_regions() function.

Also remove no longer required HAVE_MEMORY_PRESENT configuration option.

Signed-off-by: Mike Rapoport &lt;rppt@linux.ibm.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Link: http://lkml.kernel.org/r/20200712083130.22919-1-rppt@kernel.org
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm/sparse: never partially remove memmap for early section</title>
<updated>2020-08-07T18:33:27+00:00</updated>
<author>
<name>Wei Yang</name>
<email>richard.weiyang@linux.alibaba.com</email>
</author>
<published>2020-08-07T06:23:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=ef69bc9f689de8380688be742f9b9df615d42429'/>
<id>ef69bc9f689de8380688be742f9b9df615d42429</id>
<content type='text'>
For early sections, its memmap is handled specially even sub-section is
enabled.  The memmap could only be populated as a whole.

Quoted from the comment of section_activate():

    * The early init code does not consider partially populated
    * initial sections, it simply assumes that memory will never be
    * referenced.  If we hot-add memory into such a section then we
    * do not need to populate the memmap and can simply reuse what
    * is already there.

While current section_deactivate() breaks this rule.  When hot-remove a
sub-section, section_deactivate() would depopulate its memmap.  The
consequence is if we hot-add this subsection again, its memmap never get
proper populated.

We can reproduce the case by following steps:

1. Hacking qemu to allow sub-section early section

:   diff --git a/hw/i386/pc.c b/hw/i386/pc.c
:   index 51b3050d01..c6a78d83c0 100644
:   --- a/hw/i386/pc.c
:   +++ b/hw/i386/pc.c
:   @@ -1010,7 +1010,7 @@ void pc_memory_init(PCMachineState *pcms,
:            }
:
:            machine-&gt;device_memory-&gt;base =
:   -            ROUND_UP(0x100000000ULL + x86ms-&gt;above_4g_mem_size, 1 * GiB);
:   +            0x100000000ULL + x86ms-&gt;above_4g_mem_size;
:
:            if (pcmc-&gt;enforce_aligned_dimm) {
:                /* size device region assuming 1G page max alignment per slot */

2. Bootup qemu with PSE disabled and a sub-section aligned memory size

   Part of the qemu command would look like this:

   sudo x86_64-softmmu/qemu-system-x86_64 \
       --enable-kvm -cpu host,pse=off \
       -m 4160M,maxmem=20G,slots=1 \
       -smp sockets=2,cores=16 \
       -numa node,nodeid=0,cpus=0-1 -numa node,nodeid=1,cpus=2-3 \
       -machine pc,nvdimm \
       -nographic \
       -object memory-backend-ram,id=mem0,size=8G \
       -device nvdimm,id=vm0,memdev=mem0,node=0,addr=0x144000000,label-size=128k

3. Re-config a pmem device with sub-section size in guest

   ndctl create-namespace --force --reconfig=namespace0.0 --mode=devdax --size=16M

Then you would see the following call trace:

   pmem0: detected capacity change from 0 to 16777216
   BUG: unable to handle page fault for address: ffffec73c51000b4
   #PF: supervisor write access in kernel mode
   #PF: error_code(0x0002) - not-present page
   PGD 81ff8067 P4D 81ff8067 PUD 81ff7067 PMD 1437cb067 PTE 0
   Oops: 0002 [#1] SMP NOPTI
   CPU: 16 PID: 1348 Comm: ndctl Kdump: loaded Tainted: G        W         5.8.0-rc2+ #24
   Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.4
   RIP: 0010:memmap_init_zone+0x154/0x1c2
   Code: 77 16 f6 40 10 02 74 10 48 03 48 08 48 89 cb 48 c1 eb 0c e9 3a ff ff ff 48 89 df 48 c1 e7 06 48f
   RSP: 0018:ffffbdc7011a39b0 EFLAGS: 00010282
   RAX: ffffec73c5100088 RBX: 0000000000144002 RCX: 0000000000144000
   RDX: 0000000000000004 RSI: 007ffe0000000000 RDI: ffffec73c5100080
   RBP: 027ffe0000000000 R08: 0000000000000001 R09: ffff9f8d38f6d708
   R10: ffffec73c0000000 R11: 0000000000000000 R12: 0000000000000004
   R13: 0000000000000001 R14: 0000000000144200 R15: 0000000000000000
   FS:  00007efe6b65d780(0000) GS:ffff9f8d3f780000(0000) knlGS:0000000000000000
   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
   CR2: ffffec73c51000b4 CR3: 000000007d718000 CR4: 0000000000340ee0
   Call Trace:
    move_pfn_range_to_zone+0x128/0x150
    memremap_pages+0x4e4/0x5a0
    devm_memremap_pages+0x1e/0x60
    dev_dax_probe+0x69/0x160 [device_dax]
    really_probe+0x298/0x3c0
    driver_probe_device+0xe1/0x150
    ? driver_allows_async_probing+0x50/0x50
    bus_for_each_drv+0x7e/0xc0
    __device_attach+0xdf/0x160
    bus_probe_device+0x8e/0xa0
    device_add+0x3b9/0x740
    __devm_create_dev_dax+0x127/0x1c0
    __dax_pmem_probe+0x1f2/0x219 [dax_pmem_core]
    dax_pmem_probe+0xc/0x1b [dax_pmem]
    nvdimm_bus_probe+0x69/0x1c0 [libnvdimm]
    really_probe+0x147/0x3c0
    driver_probe_device+0xe1/0x150
    device_driver_attach+0x53/0x60
    bind_store+0xd1/0x110
    kernfs_fop_write+0xce/0x1b0
    vfs_write+0xb6/0x1a0
    ksys_write+0x5f/0xe0
    do_syscall_64+0x4d/0x90
    entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug")
Signed-off-by: Wei Yang &lt;richard.weiyang@linux.alibaba.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Acked-by: David Hildenbrand &lt;david@redhat.com&gt;
Cc: Oscar Salvador &lt;osalvador@suse.de&gt;
Cc: Dan Williams &lt;dan.j.williams@intel.com&gt;
Link: http://lkml.kernel.org/r/20200625223534.18024-1-richard.weiyang@linux.alibaba.com
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
For early sections, its memmap is handled specially even sub-section is
enabled.  The memmap could only be populated as a whole.

Quoted from the comment of section_activate():

    * The early init code does not consider partially populated
    * initial sections, it simply assumes that memory will never be
    * referenced.  If we hot-add memory into such a section then we
    * do not need to populate the memmap and can simply reuse what
    * is already there.

While current section_deactivate() breaks this rule.  When hot-remove a
sub-section, section_deactivate() would depopulate its memmap.  The
consequence is if we hot-add this subsection again, its memmap never get
proper populated.

We can reproduce the case by following steps:

1. Hacking qemu to allow sub-section early section

:   diff --git a/hw/i386/pc.c b/hw/i386/pc.c
:   index 51b3050d01..c6a78d83c0 100644
:   --- a/hw/i386/pc.c
:   +++ b/hw/i386/pc.c
:   @@ -1010,7 +1010,7 @@ void pc_memory_init(PCMachineState *pcms,
:            }
:
:            machine-&gt;device_memory-&gt;base =
:   -            ROUND_UP(0x100000000ULL + x86ms-&gt;above_4g_mem_size, 1 * GiB);
:   +            0x100000000ULL + x86ms-&gt;above_4g_mem_size;
:
:            if (pcmc-&gt;enforce_aligned_dimm) {
:                /* size device region assuming 1G page max alignment per slot */

2. Bootup qemu with PSE disabled and a sub-section aligned memory size

   Part of the qemu command would look like this:

   sudo x86_64-softmmu/qemu-system-x86_64 \
       --enable-kvm -cpu host,pse=off \
       -m 4160M,maxmem=20G,slots=1 \
       -smp sockets=2,cores=16 \
       -numa node,nodeid=0,cpus=0-1 -numa node,nodeid=1,cpus=2-3 \
       -machine pc,nvdimm \
       -nographic \
       -object memory-backend-ram,id=mem0,size=8G \
       -device nvdimm,id=vm0,memdev=mem0,node=0,addr=0x144000000,label-size=128k

3. Re-config a pmem device with sub-section size in guest

   ndctl create-namespace --force --reconfig=namespace0.0 --mode=devdax --size=16M

Then you would see the following call trace:

   pmem0: detected capacity change from 0 to 16777216
   BUG: unable to handle page fault for address: ffffec73c51000b4
   #PF: supervisor write access in kernel mode
   #PF: error_code(0x0002) - not-present page
   PGD 81ff8067 P4D 81ff8067 PUD 81ff7067 PMD 1437cb067 PTE 0
   Oops: 0002 [#1] SMP NOPTI
   CPU: 16 PID: 1348 Comm: ndctl Kdump: loaded Tainted: G        W         5.8.0-rc2+ #24
   Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.4
   RIP: 0010:memmap_init_zone+0x154/0x1c2
   Code: 77 16 f6 40 10 02 74 10 48 03 48 08 48 89 cb 48 c1 eb 0c e9 3a ff ff ff 48 89 df 48 c1 e7 06 48f
   RSP: 0018:ffffbdc7011a39b0 EFLAGS: 00010282
   RAX: ffffec73c5100088 RBX: 0000000000144002 RCX: 0000000000144000
   RDX: 0000000000000004 RSI: 007ffe0000000000 RDI: ffffec73c5100080
   RBP: 027ffe0000000000 R08: 0000000000000001 R09: ffff9f8d38f6d708
   R10: ffffec73c0000000 R11: 0000000000000000 R12: 0000000000000004
   R13: 0000000000000001 R14: 0000000000144200 R15: 0000000000000000
   FS:  00007efe6b65d780(0000) GS:ffff9f8d3f780000(0000) knlGS:0000000000000000
   CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
   CR2: ffffec73c51000b4 CR3: 000000007d718000 CR4: 0000000000340ee0
   Call Trace:
    move_pfn_range_to_zone+0x128/0x150
    memremap_pages+0x4e4/0x5a0
    devm_memremap_pages+0x1e/0x60
    dev_dax_probe+0x69/0x160 [device_dax]
    really_probe+0x298/0x3c0
    driver_probe_device+0xe1/0x150
    ? driver_allows_async_probing+0x50/0x50
    bus_for_each_drv+0x7e/0xc0
    __device_attach+0xdf/0x160
    bus_probe_device+0x8e/0xa0
    device_add+0x3b9/0x740
    __devm_create_dev_dax+0x127/0x1c0
    __dax_pmem_probe+0x1f2/0x219 [dax_pmem_core]
    dax_pmem_probe+0xc/0x1b [dax_pmem]
    nvdimm_bus_probe+0x69/0x1c0 [libnvdimm]
    really_probe+0x147/0x3c0
    driver_probe_device+0xe1/0x150
    device_driver_attach+0x53/0x60
    bind_store+0xd1/0x110
    kernfs_fop_write+0xce/0x1b0
    vfs_write+0xb6/0x1a0
    ksys_write+0x5f/0xe0
    do_syscall_64+0x4d/0x90
    entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: ba72b4c8cf60 ("mm/sparsemem: support sub-section hotplug")
Signed-off-by: Wei Yang &lt;richard.weiyang@linux.alibaba.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Acked-by: David Hildenbrand &lt;david@redhat.com&gt;
Cc: Oscar Salvador &lt;osalvador@suse.de&gt;
Cc: Dan Williams &lt;dan.j.williams@intel.com&gt;
Link: http://lkml.kernel.org/r/20200625223534.18024-1-richard.weiyang@linux.alibaba.com
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm: remove unneeded includes of &lt;asm/pgalloc.h&gt;</title>
<updated>2020-08-07T18:33:26+00:00</updated>
<author>
<name>Mike Rapoport</name>
<email>rppt@linux.ibm.com</email>
</author>
<published>2020-08-07T06:22:28+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=ca15ca406f660ad5fab55b851d2b269ce915c88d'/>
<id>ca15ca406f660ad5fab55b851d2b269ce915c88d</id>
<content type='text'>
Patch series "mm: cleanup usage of &lt;asm/pgalloc.h&gt;"

Most architectures have very similar versions of pXd_alloc_one() and
pXd_free_one() for intermediate levels of page table.  These patches add
generic versions of these functions in &lt;asm-generic/pgalloc.h&gt; and enable
use of the generic functions where appropriate.

In addition, functions declared and defined in &lt;asm/pgalloc.h&gt; headers are
used mostly by core mm and early mm initialization in arch and there is no
actual reason to have the &lt;asm/pgalloc.h&gt; included all over the place.
The first patch in this series removes unneeded includes of
&lt;asm/pgalloc.h&gt;

In the end it didn't work out as neatly as I hoped and moving
pXd_alloc_track() definitions to &lt;asm-generic/pgalloc.h&gt; would require
unnecessary changes to arches that have custom page table allocations, so
I've decided to move lib/ioremap.c to mm/ and make pgalloc-track.h local
to mm/.

This patch (of 8):

In most cases &lt;asm/pgalloc.h&gt; header is required only for allocations of
page table memory.  Most of the .c files that include that header do not
use symbols declared in &lt;asm/pgalloc.h&gt; and do not require that header.

As for the other header files that used to include &lt;asm/pgalloc.h&gt;, it is
possible to move that include into the .c file that actually uses symbols
from &lt;asm/pgalloc.h&gt; and drop the include from the header file.

The process was somewhat automated using

	sed -i -E '/[&lt;"]asm\/pgalloc\.h/d' \
                $(grep -L -w -f /tmp/xx \
                        $(git grep -E -l '[&lt;"]asm/pgalloc\.h'))

where /tmp/xx contains all the symbols defined in
arch/*/include/asm/pgalloc.h.

[rppt@linux.ibm.com: fix powerpc warning]

Signed-off-by: Mike Rapoport &lt;rppt@linux.ibm.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Reviewed-by: Pekka Enberg &lt;penberg@kernel.org&gt;
Acked-by: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;	[m68k]
Cc: Abdul Haleem &lt;abdhalee@linux.vnet.ibm.com&gt;
Cc: Andy Lutomirski &lt;luto@kernel.org&gt;
Cc: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Christophe Leroy &lt;christophe.leroy@csgroup.eu&gt;
Cc: Joerg Roedel &lt;joro@8bytes.org&gt;
Cc: Max Filippov &lt;jcmvbkbc@gmail.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Satheesh Rajendran &lt;sathnaga@linux.vnet.ibm.com&gt;
Cc: Stafford Horne &lt;shorne@gmail.com&gt;
Cc: Stephen Rothwell &lt;sfr@canb.auug.org.au&gt;
Cc: Steven Rostedt &lt;rostedt@goodmis.org&gt;
Cc: Joerg Roedel &lt;jroedel@suse.de&gt;
Cc: Matthew Wilcox &lt;willy@infradead.org&gt;
Link: http://lkml.kernel.org/r/20200627143453.31835-1-rppt@kernel.org
Link: http://lkml.kernel.org/r/20200627143453.31835-2-rppt@kernel.org
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Patch series "mm: cleanup usage of &lt;asm/pgalloc.h&gt;"

Most architectures have very similar versions of pXd_alloc_one() and
pXd_free_one() for intermediate levels of page table.  These patches add
generic versions of these functions in &lt;asm-generic/pgalloc.h&gt; and enable
use of the generic functions where appropriate.

In addition, functions declared and defined in &lt;asm/pgalloc.h&gt; headers are
used mostly by core mm and early mm initialization in arch and there is no
actual reason to have the &lt;asm/pgalloc.h&gt; included all over the place.
The first patch in this series removes unneeded includes of
&lt;asm/pgalloc.h&gt;

In the end it didn't work out as neatly as I hoped and moving
pXd_alloc_track() definitions to &lt;asm-generic/pgalloc.h&gt; would require
unnecessary changes to arches that have custom page table allocations, so
I've decided to move lib/ioremap.c to mm/ and make pgalloc-track.h local
to mm/.

This patch (of 8):

In most cases &lt;asm/pgalloc.h&gt; header is required only for allocations of
page table memory.  Most of the .c files that include that header do not
use symbols declared in &lt;asm/pgalloc.h&gt; and do not require that header.

As for the other header files that used to include &lt;asm/pgalloc.h&gt;, it is
possible to move that include into the .c file that actually uses symbols
from &lt;asm/pgalloc.h&gt; and drop the include from the header file.

The process was somewhat automated using

	sed -i -E '/[&lt;"]asm\/pgalloc\.h/d' \
                $(grep -L -w -f /tmp/xx \
                        $(git grep -E -l '[&lt;"]asm/pgalloc\.h'))

where /tmp/xx contains all the symbols defined in
arch/*/include/asm/pgalloc.h.

[rppt@linux.ibm.com: fix powerpc warning]

Signed-off-by: Mike Rapoport &lt;rppt@linux.ibm.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Reviewed-by: Pekka Enberg &lt;penberg@kernel.org&gt;
Acked-by: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;	[m68k]
Cc: Abdul Haleem &lt;abdhalee@linux.vnet.ibm.com&gt;
Cc: Andy Lutomirski &lt;luto@kernel.org&gt;
Cc: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Christophe Leroy &lt;christophe.leroy@csgroup.eu&gt;
Cc: Joerg Roedel &lt;joro@8bytes.org&gt;
Cc: Max Filippov &lt;jcmvbkbc@gmail.com&gt;
Cc: Peter Zijlstra &lt;peterz@infradead.org&gt;
Cc: Satheesh Rajendran &lt;sathnaga@linux.vnet.ibm.com&gt;
Cc: Stafford Horne &lt;shorne@gmail.com&gt;
Cc: Stephen Rothwell &lt;sfr@canb.auug.org.au&gt;
Cc: Steven Rostedt &lt;rostedt@goodmis.org&gt;
Cc: Joerg Roedel &lt;jroedel@suse.de&gt;
Cc: Matthew Wilcox &lt;willy@infradead.org&gt;
Link: http://lkml.kernel.org/r/20200627143453.31835-1-rppt@kernel.org
Link: http://lkml.kernel.org/r/20200627143453.31835-2-rppt@kernel.org
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mm: don't include asm/pgtable.h if linux/mm.h is already included</title>
<updated>2020-06-09T16:39:13+00:00</updated>
<author>
<name>Mike Rapoport</name>
<email>rppt@linux.ibm.com</email>
</author>
<published>2020-06-09T04:32:33+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=e31cf2f4ca422ac9b14ecc4a1295b8977a20f812'/>
<id>e31cf2f4ca422ac9b14ecc4a1295b8977a20f812</id>
<content type='text'>
Patch series "mm: consolidate definitions of page table accessors", v2.

The low level page table accessors (pXY_index(), pXY_offset()) are
duplicated across all architectures and sometimes more than once.  For
instance, we have 31 definition of pgd_offset() for 25 supported
architectures.

Most of these definitions are actually identical and typically it boils
down to, e.g.

static inline unsigned long pmd_index(unsigned long address)
{
        return (address &gt;&gt; PMD_SHIFT) &amp; (PTRS_PER_PMD - 1);
}

static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address)
{
        return (pmd_t *)pud_page_vaddr(*pud) + pmd_index(address);
}

These definitions can be shared among 90% of the arches provided
XYZ_SHIFT, PTRS_PER_XYZ and xyz_page_vaddr() are defined.

For architectures that really need a custom version there is always
possibility to override the generic version with the usual ifdefs magic.

These patches introduce include/linux/pgtable.h that replaces
include/asm-generic/pgtable.h and add the definitions of the page table
accessors to the new header.

This patch (of 12):

The linux/mm.h header includes &lt;asm/pgtable.h&gt; to allow inlining of the
functions involving page table manipulations, e.g.  pte_alloc() and
pmd_alloc().  So, there is no point to explicitly include &lt;asm/pgtable.h&gt;
in the files that include &lt;linux/mm.h&gt;.

The include statements in such cases are remove with a simple loop:

	for f in $(git grep -l "include &lt;linux/mm.h&gt;") ; do
		sed -i -e '/include &lt;asm\/pgtable.h&gt;/ d' $f
	done

Signed-off-by: Mike Rapoport &lt;rppt@linux.ibm.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Borislav Petkov &lt;bp@alien8.de&gt;
Cc: Brian Cain &lt;bcain@codeaurora.org&gt;
Cc: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Cc: Chris Zankel &lt;chris@zankel.net&gt;
Cc: "David S. Miller" &lt;davem@davemloft.net&gt;
Cc: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Cc: Greentime Hu &lt;green.hu@gmail.com&gt;
Cc: Greg Ungerer &lt;gerg@linux-m68k.org&gt;
Cc: Guan Xuetao &lt;gxt@pku.edu.cn&gt;
Cc: Guo Ren &lt;guoren@kernel.org&gt;
Cc: Heiko Carstens &lt;heiko.carstens@de.ibm.com&gt;
Cc: Helge Deller &lt;deller@gmx.de&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Ley Foon Tan &lt;ley.foon.tan@intel.com&gt;
Cc: Mark Salter &lt;msalter@redhat.com&gt;
Cc: Matthew Wilcox &lt;willy@infradead.org&gt;
Cc: Matt Turner &lt;mattst88@gmail.com&gt;
Cc: Max Filippov &lt;jcmvbkbc@gmail.com&gt;
Cc: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Cc: Michal Simek &lt;monstr@monstr.eu&gt;
Cc: Mike Rapoport &lt;rppt@kernel.org&gt;
Cc: Nick Hu &lt;nickhu@andestech.com&gt;
Cc: Paul Walmsley &lt;paul.walmsley@sifive.com&gt;
Cc: Richard Weinberger &lt;richard@nod.at&gt;
Cc: Rich Felker &lt;dalias@libc.org&gt;
Cc: Russell King &lt;linux@armlinux.org.uk&gt;
Cc: Stafford Horne &lt;shorne@gmail.com&gt;
Cc: Thomas Bogendoerfer &lt;tsbogend@alpha.franken.de&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Tony Luck &lt;tony.luck@intel.com&gt;
Cc: Vincent Chen &lt;deanbo422@gmail.com&gt;
Cc: Vineet Gupta &lt;vgupta@synopsys.com&gt;
Cc: Will Deacon &lt;will@kernel.org&gt;
Cc: Yoshinori Sato &lt;ysato@users.sourceforge.jp&gt;
Link: http://lkml.kernel.org/r/20200514170327.31389-1-rppt@kernel.org
Link: http://lkml.kernel.org/r/20200514170327.31389-2-rppt@kernel.org
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Patch series "mm: consolidate definitions of page table accessors", v2.

The low level page table accessors (pXY_index(), pXY_offset()) are
duplicated across all architectures and sometimes more than once.  For
instance, we have 31 definition of pgd_offset() for 25 supported
architectures.

Most of these definitions are actually identical and typically it boils
down to, e.g.

static inline unsigned long pmd_index(unsigned long address)
{
        return (address &gt;&gt; PMD_SHIFT) &amp; (PTRS_PER_PMD - 1);
}

static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address)
{
        return (pmd_t *)pud_page_vaddr(*pud) + pmd_index(address);
}

These definitions can be shared among 90% of the arches provided
XYZ_SHIFT, PTRS_PER_XYZ and xyz_page_vaddr() are defined.

For architectures that really need a custom version there is always
possibility to override the generic version with the usual ifdefs magic.

These patches introduce include/linux/pgtable.h that replaces
include/asm-generic/pgtable.h and add the definitions of the page table
accessors to the new header.

This patch (of 12):

The linux/mm.h header includes &lt;asm/pgtable.h&gt; to allow inlining of the
functions involving page table manipulations, e.g.  pte_alloc() and
pmd_alloc().  So, there is no point to explicitly include &lt;asm/pgtable.h&gt;
in the files that include &lt;linux/mm.h&gt;.

The include statements in such cases are remove with a simple loop:

	for f in $(git grep -l "include &lt;linux/mm.h&gt;") ; do
		sed -i -e '/include &lt;asm\/pgtable.h&gt;/ d' $f
	done

Signed-off-by: Mike Rapoport &lt;rppt@linux.ibm.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Cc: Arnd Bergmann &lt;arnd@arndb.de&gt;
Cc: Borislav Petkov &lt;bp@alien8.de&gt;
Cc: Brian Cain &lt;bcain@codeaurora.org&gt;
Cc: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Cc: Chris Zankel &lt;chris@zankel.net&gt;
Cc: "David S. Miller" &lt;davem@davemloft.net&gt;
Cc: Geert Uytterhoeven &lt;geert@linux-m68k.org&gt;
Cc: Greentime Hu &lt;green.hu@gmail.com&gt;
Cc: Greg Ungerer &lt;gerg@linux-m68k.org&gt;
Cc: Guan Xuetao &lt;gxt@pku.edu.cn&gt;
Cc: Guo Ren &lt;guoren@kernel.org&gt;
Cc: Heiko Carstens &lt;heiko.carstens@de.ibm.com&gt;
Cc: Helge Deller &lt;deller@gmx.de&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: Ley Foon Tan &lt;ley.foon.tan@intel.com&gt;
Cc: Mark Salter &lt;msalter@redhat.com&gt;
Cc: Matthew Wilcox &lt;willy@infradead.org&gt;
Cc: Matt Turner &lt;mattst88@gmail.com&gt;
Cc: Max Filippov &lt;jcmvbkbc@gmail.com&gt;
Cc: Michael Ellerman &lt;mpe@ellerman.id.au&gt;
Cc: Michal Simek &lt;monstr@monstr.eu&gt;
Cc: Mike Rapoport &lt;rppt@kernel.org&gt;
Cc: Nick Hu &lt;nickhu@andestech.com&gt;
Cc: Paul Walmsley &lt;paul.walmsley@sifive.com&gt;
Cc: Richard Weinberger &lt;richard@nod.at&gt;
Cc: Rich Felker &lt;dalias@libc.org&gt;
Cc: Russell King &lt;linux@armlinux.org.uk&gt;
Cc: Stafford Horne &lt;shorne@gmail.com&gt;
Cc: Thomas Bogendoerfer &lt;tsbogend@alpha.franken.de&gt;
Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Tony Luck &lt;tony.luck@intel.com&gt;
Cc: Vincent Chen &lt;deanbo422@gmail.com&gt;
Cc: Vineet Gupta &lt;vgupta@synopsys.com&gt;
Cc: Will Deacon &lt;will@kernel.org&gt;
Cc: Yoshinori Sato &lt;ysato@users.sourceforge.jp&gt;
Link: http://lkml.kernel.org/r/20200514170327.31389-1-rppt@kernel.org
Link: http://lkml.kernel.org/r/20200514170327.31389-2-rppt@kernel.org
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
</feed>
