mm/mempolicy: fix comments for better documentation

Fix typo in mempolicy.h and Correct the number of allowed memory policy

Link: https://lkml.kernel.org/r/20240926183516.4034-2-tanyaagarwal25699@g

mm/mempolicy: fix comments for better documentation

Fix typo in mempolicy.h and Correct the number of allowed memory policy

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Tanya Agarwal <[email protected]>
Reviewed-by: Shuah Khan <[email protected]>
Cc: Anup Sharma <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm/mempolicy: use numa_node_id() instead of cpu_to_node()

Patch series "Allow migrate on protnone reference with MPOL_PREFERRED_MANY
policy:, v4.

This patchset is to optimize the cross-socket memor

mm/mempolicy: use numa_node_id() instead of cpu_to_node()

Patch series "Allow migrate on protnone reference with MPOL_PREFERRED_MANY
policy:, v4.

This patchset is to optimize the cross-socket memory access with
MPOL_PREFERRED_MANY policy.

To test this patch we ran the following test on a 3 node system.
Node 0 - 2GB - Tier 1
Node 1 - 11GB - Tier 1
Node 6 - 10GB - Tier 2

Below changes are made to memcached to set the memory policy,
It select Node0 and Node1 as preferred nodes.

#include <numaif.h>
#include <numa.h>

unsigned long nodemask;
int ret;

nodemask = 0x03;
ret = set_mempolicy(MPOL_PREFERRED_MANY | MPOL_F_NUMA_BALANCING,
&nodemask, 10);
/* If MPOL_F_NUMA_BALANCING isn't supported,
* fall back to MPOL_PREFERRED_MANY */
if (ret < 0 && errno == EINVAL){
printf("set mem policy normal\n");
ret = set_mempolicy(MPOL_PREFERRED_MANY, &nodemask, 10);
}
if (ret < 0) {
perror("Failed to call set_mempolicy");
exit(-1);
}

Test Procedure:
===============
1. Make sure memory tiring and demotion are enabled.
2. Start memcached.

# ./memcached -b 100000 -m 204800 -u root -c 1000000 -t 7
-d -s "/tmp/memcached.sock"

3. Run memtier_benchmark to store 3200000 keys.

#./memtier_benchmark -S "/tmp/memcached.sock" --protocol=memcache_binary
--threads=1 --pipeline=1 --ratio=1:0 --key-pattern=S:S --key-minimum=1
--key-maximum=3200000 -n allkeys -c 1 -R -x 1 -d 1024

4. Start a memory eater on node 0 and 1. This will demote all memcached
pages to node 6.
5. Make sure all the memcached pages got demoted to lower tier by reading
/proc/<memcaced PID>/numa_maps.

# cat /proc/2771/numa_maps
---
default anon=1009 dirty=1009 active=0 N6=1009 kernelpagesize_kB=64
default anon=1009 dirty=1009 active=0 N6=1009 kernelpagesize_kB=64
---

6. Kill memory eater.
7. Read the pgpromote_success counter.
8. Start reading the keys by running memtier_benchmark.

#./memtier_benchmark -S "/tmp/memcached.sock" --protocol=memcache_binary
--pipeline=1 --distinct-client-seed --ratio=0:3 --key-pattern=R:R
--key-minimum=1 --key-maximum=3200000 -n allkeys
--threads=64 -c 1 -R -x 6

9. Read the pgpromote_success counter.

Test Results:
=============
Without Patch
------------------
1. pgpromote_success before test
Node 0: pgpromote_success 11
Node 1: pgpromote_success 140974

pgpromote_success after test
Node 0: pgpromote_success 11
Node 1: pgpromote_success 140974

2. Memtier-benchmark result.
AGGREGATED AVERAGE RESULTS (6 runs)
==================================================================
Type Ops/sec Hits/sec Misses/sec Avg. Latency p50 Latency
------------------------------------------------------------------
Sets 0.00 --- --- --- ---
Gets 305792.03 305791.93 0.10 0.18949 0.16700
Waits 0.00 --- --- --- ---
Totals 305792.03 305791.93 0.10 0.18949 0.16700

======================================
p99 Latency p99.9 Latency KB/sec
-------------------------------------
--- --- 0.00
0.44700 1.71100 11542.69
--- --- ---
0.44700 1.71100 11542.69

With Patch
---------------
1. pgpromote_success before test
Node 0: pgpromote_success 5
Node 1: pgpromote_success 89386

pgpromote_success after test
Node 0: pgpromote_success 57895
Node 1: pgpromote_success 141463

2. Memtier-benchmark result.
AGGREGATED AVERAGE RESULTS (6 runs)
====================================================================
Type Ops/sec Hits/sec Misses/sec Avg. Latency p50 Latency
--------------------------------------------------------------------
Sets 0.00 --- --- --- ---
Gets 521942.24 521942.07 0.17 0.11459 0.10300
Waits 0.00 --- --- --- ---
Totals 521942.24 521942.07 0.17 0.11459 0.10300

=======================================
p99 Latency p99.9 Latency KB/sec
---------------------------------------
--- --- 0.00
0.23100 0.31900 19701.68
--- --- ---
0.23100 0.31900 19701.68


Test Result Analysis:
=====================
1. With patch we could observe pages are getting promoted.
2. Memtier-benchmark results shows that, with the patch,
performance has increased more than 50%.

Ops/sec without fix - 305792.03
Ops/sec with fix - 521942.24


This patch (of 2):

Instead of using 'cpu_to_node()', we use 'numa_node_id()', which is
quicker. smp_processor_id is guaranteed to be stable in the
'mpol_misplaced()' function because it is called with ptl held.
lockdep_assert_held was added to ensure that.

No functional change in this patch.

[[email protected]: add "* @vmf: structure describing the fault" comment]
Link: https://lkml.kernel.org/r/d8b993ea9dccfac0bc3ed61d3a81f4ac5f376e46.1711002865.git.donettom@linux.ibm.com
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/6059f034f436734b472d066db69676fb3a459864.1711373653.git.donettom@linux.ibm.com
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/744646531af02cc687cde8ae788fb1779e99d02c.1709909210.git.donettom@linux.ibm.com
Signed-off-by: Aneesh Kumar K.V (IBM) <[email protected]>
Signed-off-by: Donet Tom <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Feng Tang <[email protected]>
Cc: Huang, Ying <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Kefeng Wang <[email protected]>
Cc: "Matthew Wilcox (Oracle)" <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Rik van Riel <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mempolicy: alloc_pages_mpol() for NUMA policy without vma

Shrink shmem's stack usage by eliminating the pseudo-vma from its folio
allocation. alloc_pages_mpol(gfp, order, pol, ilx, nid) becomes the

mempolicy: alloc_pages_mpol() for NUMA policy without vma

Shrink shmem's stack usage by eliminating the pseudo-vma from its folio
allocation. alloc_pages_mpol(gfp, order, pol, ilx, nid) becomes the
principal actor for passing mempolicy choice down to __alloc_pages(),
rather than vma_alloc_folio(gfp, order, vma, addr, hugepage).

vma_alloc_folio() and alloc_pages() remain, but as wrappers around
alloc_pages_mpol(). alloc_pages_bulk_*() untouched, except to provide the
additional args to policy_nodemask(), which subsumes policy_node().
Cleanup throughout, cutting out some unhelpful "helpers".

It would all be much simpler without MPOL_INTERLEAVE, but that adds a
dynamic to the constant mpol: complicated by v3.6 commit 09c231cb8bfd
("tmpfs: distribute interleave better across nodes"), which added ino bias
to the interleave, hidden from mm/mempolicy.c until this commit.

Hence "ilx" throughout, the "interleave index". Originally I thought it
could be done just with nid, but that's wrong: the nodemask may come from
the shared policy layer below a shmem vma, or it may come from the task
layer above a shmem vma; and without the final nodemask then nodeid cannot
be decided. And how ilx is applied depends also on page order.

The interleave index is almost always irrelevant unless MPOL_INTERLEAVE:
with one exception in alloc_pages_mpol(), where the NO_INTERLEAVE_INDEX
passed down from vma-less alloc_pages() is also used as hint not to use
THP-style hugepage allocation - to avoid the overhead of a hugepage arg
(though I don't understand why we never just added a GFP bit for THP - if
it actually needs a different allocation strategy from other pages of the
same order). vma_alloc_folio() still carries its hugepage arg here, but
it is not used, and should be removed when agreed.

get_vma_policy() no longer allows a NULL vma: over time I believe we've
eradicated all the places which used to need it e.g. swapoff and madvise
used to pass NULL vma to read_swap_cache_async(), but now know the vma.

[[email protected]: handle NULL mpol being passed to __read_swap_cache_async()]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Hugh Dickins <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Huang Ying <[email protected]>
Cc: Kefeng Wang <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Nhat Pham <[email protected]>
Cc: Sidhartha Kumar <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Tejun heo <[email protected]>
Cc: Vishal Moola (Oracle) <[email protected]>
Cc: Yang Shi <[email protected]>
Cc: Yosry Ahmed <[email protected]>
Cc: Domenico Cerasuolo <[email protected]>
Cc: Johannes Weiner <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mempolicy trivia: use pgoff_t in shared mempolicy tree

Prefer the more explicit "pgoff_t" to "unsigned long" when dealing with a
shared mempolicy tree. Delete confusing comment about pseudo mm vmas

mempolicy trivia: use pgoff_t in shared mempolicy tree

Prefer the more explicit "pgoff_t" to "unsigned long" when dealing with a
shared mempolicy tree. Delete confusing comment about pseudo mm vmas.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Hugh Dickins <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: "Huang, Ying" <[email protected]>
Cc: Kefeng Wang <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Nhat Pham <[email protected]>
Cc: Sidhartha Kumar <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Tejun heo <[email protected]>
Cc: Vishal Moola (Oracle) <[email protected]>
Cc: Yang Shi <[email protected]>
Cc: Yosry Ahmed <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mempolicy trivia: slightly more consistent naming

Before getting down to work, do a little cleanup, mainly of inconsistent
variable naming. I gave up trying to rationalize mpol versus pol versus
po

mempolicy trivia: slightly more consistent naming

Before getting down to work, do a little cleanup, mainly of inconsistent
variable naming. I gave up trying to rationalize mpol versus pol versus
policy, and node versus nid, but let's avoid p and nd. Remove a few
superfluous blank lines, but add one; and here prefer vma->vm_policy to
vma_policy(vma) - the latter being appropriate in other sources, which
have to allow for !CONFIG_NUMA. That intriguing line about KERNEL_DS?
should have gone in v2.6.15, when numa_policy_init() stopped using
set_mempolicy(2)'s system call handler.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Hugh Dickins <[email protected]>
Reviewed-by: Matthew Wilcox (Oracle) <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: "Huang, Ying" <[email protected]>
Cc: Kefeng Wang <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Nhat Pham <[email protected]>
Cc: Sidhartha Kumar <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Cc: Tejun heo <[email protected]>
Cc: Vishal Moola (Oracle) <[email protected]>
Cc: Yang Shi <[email protected]>
Cc: Yosry Ahmed <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: move vma_policy() and anon_vma_name() decls to mm_types.h

Patch series "Abstract vma_merge() and split_vma()", v4.

The vma_merge() interface is very confusing and its implementation has led
to

mm: move vma_policy() and anon_vma_name() decls to mm_types.h

Patch series "Abstract vma_merge() and split_vma()", v4.

The vma_merge() interface is very confusing and its implementation has led
to numerous bugs as a result of that confusion.

In addition there is duplication both in invocation of vma_merge(), but
also in the common mprotect()-style pattern of attempting a merge, then if
this fails, splitting the portion of a VMA about to have its attributes
changed.

This pattern has been copy/pasted around the kernel in each instance where
such an operation has been required, each very slightly modified from the
last to make it even harder to decipher what is going on.

Simplify the whole thing by dividing the actual uses of vma_merge() and
split_vma() into specific and abstracted functions and de-duplicate the
vma_merge()/split_vma() pattern altogether.

Doing so also opens the door to changing how vma_merge() is implemented -
by knowing precisely what cases a caller is invoking rather than having a
central interface where anything might happen we can untangle the brittle
and confusing vma_merge() implementation into something more workable.

For mprotect()-like cases we introduce vma_modify() which performs the
vma_merge()/split_vma() pattern, returning a pointer to either the merged
or split VMA or an ERR_PTR(err) if the splits fail.

We provide a number of inline helper functions to make things even clearer:-

* vma_modify_flags() - Prepare to modify the VMA's flags.
* vma_modify_flags_name() - Prepare to modify the VMA's flags/anon_vma_name
* vma_modify_policy() - Prepare to modify the VMA's mempolicy.
* vma_modify_flags_uffd() - Prepare to modify the VMA's flags/uffd context.

For cases where a new VMA is attempted to be merged with adjacent VMAs we
add:-

* vma_merge_new_vma() - Prepare to merge a new VMA.
* vma_merge_extend() - Prepare to extend the end of a new VMA.


This patch (of 5):

The vma_policy() define is a helper specifically for a VMA field so it
makes sense to host it in the memory management types header.

The anon_vma_name(), anon_vma_name_alloc() and anon_vma_name_free()
functions are a little out of place in mm_inline.h as they define external
functions, and so it makes sense to locate them in mm_types.h.

The purpose of these relocations is to make it possible to abstract static
inline wrappers which invoke both of these helpers.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/24bfc6c9e382fffbcb0ea8d424392c27d56cc8ca.1697043508.git.lstoakes@gmail.com
Signed-off-by: Lorenzo Stoakes <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]>
Cc: Alexander Viro <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Liam R. Howlett <[email protected]>
Cc: Lorenzo Stoakes <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm: mempolicy: make mpol_misplaced() to take a folio

In preparation for large folio numa balancing, make mpol_misplaced() to
take a folio, no functional change intended.

Link: https://lkml.kernel.o

mm: mempolicy: make mpol_misplaced() to take a folio

In preparation for large folio numa balancing, make mpol_misplaced() to
take a folio, no functional change intended.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Kefeng Wang <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: "Huang, Ying" <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Zi Yan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm/hugetlb: add dedicated func to get 'allowed' nodemask for current process

Muchun Song found that after MPOL_PREFERRED_MANY policy was introduced in
commit b27abaccf8e8 ("mm/mempolicy: add MPOL_PR

mm/hugetlb: add dedicated func to get 'allowed' nodemask for current process

Muchun Song found that after MPOL_PREFERRED_MANY policy was introduced in
commit b27abaccf8e8 ("mm/mempolicy: add MPOL_PREFERRED_MANY for multiple
preferred nodes"), the policy_nodemask_current()'s semantics for this new
policy has been changed, which returns 'preferred' nodes instead of
'allowed' nodes.

With the changed semantic of policy_nodemask_current, a task with
MPOL_PREFERRED_MANY policy could fail to get its reservation even though
it can fall back to other nodes (either defined by cpusets or all online
nodes) for that reservation failing mmap calles unnecessarily early.

The fix is to not consider MPOL_PREFERRED_MANY for reservations at all
because they, unlike MPOL_MBIND, do not pose any actual hard constrain.

Michal suggested the policy_nodemask_current() is only used by hugetlb,
and could be moved to hugetlb code with more explicit name to enforce the
'allowed' semantics for which only MPOL_BIND policy matters.

apply_policy_zone() is made extern to be called in hugetlb code and its
return value is changed to bool.

[1]. https://lore.kernel.org/lkml/[email protected]/t/

Link: https://lkml.kernel.org/r/[email protected]
Fixes: b27abaccf8e8 ("mm/mempolicy: add MPOL_PREFERRED_MANY for multiple preferred nodes")
Signed-off-by: Feng Tang <[email protected]>
Reported-by: Muchun Song <[email protected]>
Suggested-by: Michal Hocko <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Reviewed-by: Muchun Song <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Ben Widawsky <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

show more ...

mm/mempolicy: add set_mempolicy_home_node syscall

This syscall can be used to set a home node for the MPOL_BIND and
MPOL_PREFERRED_MANY memory policy. Users should use this syscall after
setting up

mm/mempolicy: add set_mempolicy_home_node syscall

This syscall can be used to set a home node for the MPOL_BIND and
MPOL_PREFERRED_MANY memory policy. Users should use this syscall after
setting up a memory policy for the specified range as shown below.

mbind(p, nr_pages * page_size, MPOL_BIND, new_nodes->maskp,
new_nodes->size + 1, 0);
sys_set_mempolicy_home_node((unsigned long)p, nr_pages * page_size,
home_node, 0);

The syscall allows specifying a home node/preferred node from which
kernel will fulfill memory allocation requests first.

For address range with MPOL_BIND memory policy, if nodemask specifies
more than one node, page allocations will come from the node in the
nodemask with sufficient free memory that is closest to the home
node/preferred node.

For MPOL_PREFERRED_MANY if the nodemask specifies more than one node,
page allocation will come from the node in the nodemask with sufficient
free memory that is closest to the home node/preferred node. If there
is not enough memory in all the nodes specified in the nodemask, the
allocation will be attempted from the closest numa node to the home node
in the system.

This helps applications to hint at a memory allocation preference node
and fallback to _only_ a set of nodes if the memory is not available on
the preferred node. Fallback allocation is attempted from the node
which is nearest to the preferred node.

This helps applications to have control on memory allocation numa nodes
and avoids default fallback to slow memory NUMA nodes. For example a
system with NUMA nodes 1,2 and 3 with DRAM memory and 10, 11 and 12 of
slow memory

new_nodes = numa_bitmask_alloc(nr_nodes);

numa_bitmask_setbit(new_nodes, 1);
numa_bitmask_setbit(new_nodes, 2);
numa_bitmask_setbit(new_nodes, 3);

p = mmap(NULL, nr_pages * page_size, protflag, mapflag, -1, 0);
mbind(p, nr_pages * page_size, MPOL_BIND, new_nodes->maskp, new_nodes->size + 1, 0);

sys_set_mempolicy_home_node(p, nr_pages * page_size, 2, 0);

This will allocate from nodes closer to node 2 and will make sure the
kernel will only allocate from nodes 1, 2, and 3. Memory will not be
allocated from slow memory nodes 10, 11, and 12. This differs from
default MPOL_BIND behavior in that with default MPOL_BIND the allocation
will be attempted from node closer to the local node. One of the
reasons to specify a home node is to allow allocations from cpu less
NUMA node and its nearby NUMA nodes.

With MPOL_PREFERRED_MANY on the other hand will first try to allocate
from the closest node to node 2 from the node list 1, 2 and 3. If those
nodes don't have enough memory, kernel will allocate from slow memory
node 10, 11 and 12 which ever is closer to node 2.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Aneesh Kumar K.V <[email protected]>
Cc: Ben Widawsky <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Feng Tang <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Huang Ying <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

mm: migrate: make demotion knob depend on migration

The memory demotion needs to call migrate_pages() to do the jobs. And
it is controlled by a knob, however, the knob doesn't depend on
CONFIG_MIGR

mm: migrate: make demotion knob depend on migration

The memory demotion needs to call migrate_pages() to do the jobs. And
it is controlled by a knob, however, the knob doesn't depend on
CONFIG_MIGRATION. The knob could be truned on even though MIGRATION is
disabled, this will not cause any crash since migrate_pages() would just
return -ENOSYS. But it is definitely not optimal to go through demotion
path then retry regular swap every time.

And it doesn't make too much sense to have the knob visible to the users
when !MIGRATION. Move the related code from mempolicy.[h|c] to
migrate.[h|c].

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Yang Shi <[email protected]>
Acked-by: "Huang, Ying" <[email protected]>
Cc: Dave Hansen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

mm: don't include <linux/dax.h> in <linux/mempolicy.h>

Not required at all, and having this causes a huge kernel rebuild as
soon as something in dax.h changes.

Link: https://lkml.kernel.org/r/20210

mm: don't include <linux/dax.h> in <linux/mempolicy.h>

Not required at all, and having this causes a huge kernel rebuild as
soon as something in dax.h changes.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Christoph Hellwig <[email protected]>
Reviewed-by: Naoya Horiguchi <[email protected]>
Reviewed-by: Dan Williams <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY

Implement the missing huge page allocation functionality while obeying the
preferred node semantics. This is similar to the implementation

mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY

Implement the missing huge page allocation functionality while obeying the
preferred node semantics. This is similar to the implementation for
general page allocation, as it uses a fallback mechanism to try multiple
preferred nodes first, and then all other nodes.

To avoid adding too many "#ifdef CONFIG_NUMA" check, add a helper function
in mempolicy.h to check whether a mempolicy is MPOL_PREFERRED_MANY.

[[email protected]: fix compiling issue when merging with other hugetlb patch]
[Thanks to 0day bot for catching the !CONFIG_NUMA compiling issue]
[[email protected]: suggest to remove the #ifdef CONFIG_NUMA check]
[[email protected]: add helpers to avoid ifdefs]
Link: https://lore.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
[[email protected]: initialize page to NULL in alloc_buddy_huge_page_with_mpol()]
Link: https://lkml.kernel.org/r/[email protected]

Link: https://lore.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Ben Widawsky <[email protected]>
Signed-off-by: Feng Tang <[email protected]>
Signed-off-by: Nathan Chancellor <[email protected]>
Co-developed-by: Feng Tang <[email protected]>
Suggested-by: Michal Hocko <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

mm/migrate: add sysfs interface to enable reclaim migration

Some method is obviously needed to enable reclaim-based migration.

Just like traditional autonuma, there will be some workloads that will

mm/migrate: add sysfs interface to enable reclaim migration

Some method is obviously needed to enable reclaim-based migration.

Just like traditional autonuma, there will be some workloads that will
benefit like workloads with more "static" configurations where hot pages
stay hot and cold pages stay cold. If pages come and go from the hot and
cold sets, the benefits of this approach will be more limited.

The benefits are truly workload-based and *not* hardware-based. We do not
believe that there is a viable threshold where certain hardware
configurations should have this mechanism enabled while others do not.

To be conservative, earlier work defaulted to disable reclaim- based
migration and did not include a mechanism to enable it. This proposes add
a new sysfs file

/sys/kernel/mm/numa/demotion_enabled

as a method to enable it.

We are open to any alternative that allows end users to enable this
mechanism or disable it if workload harm is detected (just like
traditional autonuma).

Once this is enabled page demotion may move data to a NUMA node that does
not fall into the cpuset of the allocating process. This could be
construed to violate the guarantees of cpusets. However, since this is an
opt-in mechanism, the assumption is that anyone enabling it is content to
relax the guarantees.

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Huang Ying <[email protected]>
Originally-by: Dave Hansen <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Wei Xu <[email protected]>
Cc: Yang Shi <[email protected]>
Cc: Zi Yan <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Greg Thelen <[email protected]>
Cc: Keith Busch <[email protected]>
Cc: Oscar Salvador <[email protected]>
Cc: Yang Shi <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

mm/mempolicy: use unified 'nodes' for bind/interleave/prefer policies

Current structure 'mempolicy' uses a union to store the node info for
bind/interleave/perfer policies.

union {
short pref

mm/mempolicy: use unified 'nodes' for bind/interleave/prefer policies

Current structure 'mempolicy' uses a union to store the node info for
bind/interleave/perfer policies.

union {
short preferred_node; /* preferred */
nodemask_t nodes; /* interleave/bind */
/* undefined for default */
} v;

Since preferred node can also be represented by a nodemask_t with only ont
bit set, unify these policies with using one nodemask_t 'nodes', which can
remove a union, simplify the code and make it easier to support future's
new policy's node info.

Link: https://lore.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Co-developed-by: Feng Tang <[email protected]>
Signed-off-by: Ben Widawsky <[email protected]>
Signed-off-by: Feng Tang <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Andi Kleen <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

mm/mempolicy: cleanup nodemask intersection check for oom

Patch series "mm/mempolicy: some fix and semantics cleanup", v4.

Current memory policy code has some confusing and ambiguous part about
MPO

mm/mempolicy: cleanup nodemask intersection check for oom

Patch series "mm/mempolicy: some fix and semantics cleanup", v4.

Current memory policy code has some confusing and ambiguous part about
MPOL_LOCAL policy, as it is handled as a faked MPOL_PREFERRED one, and
there are many places having to distinguish them. Also the nodemask
intersection check needs cleanup to be more explicit for OOM use, and
handle MPOL_INTERLEAVE correctly. This patchset cleans up these and
unifies the parameter sanity check for mbind() and set_mempolicy().

This patch (of 3):

mempolicy_nodemask_intersects seem to be a general purpose mempolicy
function. In fact it is partially tailored for the OOM purpose
instead. The oom proper is the only existing user so rename the
function to make that purpose explicit.

While at it drop the MPOL_INTERLEAVE as those allocations never has a
nodemask defined (see alloc_page_interleave) so this is a dead code and
a confusing one because MPOL_INTERLEAVE is a hint rather than a hard
requirement so it shouldn't be considered during the OOM.

The final code can be reduced to a check for MPOL_BIND which is the
only memory policy that is a hard requirement and thus relevant to a
constrained OOM logic.

[[email protected]: changelog edits]

Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Feng Tang <[email protected]>
Suggested-by: Michal Hocko <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Ben Widawsky <[email protected]>
Cc: Dan Williams <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Huang Ying <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Randy Dunlap <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

include/linux/mempolicy.h: fix typo

Change "interlave" to "interleave".

Signed-off-by: Yanfei Xu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Andr

include/linux/mempolicy.h: fix typo

Change "interlave" to "interleave".

Signed-off-by: Yanfei Xu <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

mm/hugetlb: add mempolicy check in the reservation routine

In the reservation routine, we only check whether the cpuset meets the
memory allocation requirements. But we ignore the mempolicy of MPOL

mm/hugetlb: add mempolicy check in the reservation routine

In the reservation routine, we only check whether the cpuset meets the
memory allocation requirements. But we ignore the mempolicy of MPOL_BIND
case. If someone mmap hugetlb succeeds, but the subsequent memory
allocation may fail due to mempolicy restrictions and receives the SIGBUS
signal. This can be reproduced by the follow steps.

1) Compile the test case.
cd tools/testing/selftests/vm/
gcc map_hugetlb.c -o map_hugetlb

2) Pre-allocate huge pages. Suppose there are 2 numa nodes in the
system. Each node will pre-allocate one huge page.
echo 2 > /proc/sys/vm/nr_hugepages

3) Run test case(mmap 4MB). We receive the SIGBUS signal.
numactl --membind=3D0 ./map_hugetlb 4

With this patch applied, the mmap will fail in the step 3) and throw
"mmap: Cannot allocate memory".

[[email protected]: include sched.h for `current']

Reported-by: Jianchao Guo <[email protected]>
Suggested-by: Michal Hocko <[email protected]>
Signed-off-by: Muchun Song <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Mike Kravetz <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michel Lespinasse <[email protected]>
Cc: Baoquan He <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

mmap locking API: convert mmap_sem comments

Convert comments that reference mmap_sem to reference mmap_lock instead.

[[email protected]: fix up linux-next leftovers]
[akpm@linux-foundation.

mmap locking API: convert mmap_sem comments

Convert comments that reference mmap_sem to reference mmap_lock instead.

[[email protected]: fix up linux-next leftovers]
[[email protected]: s/lockaphore/lock/, per Vlastimil]
[[email protected]: more linux-next fixups, per Michel]

Signed-off-by: Michel Lespinasse <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Vlastimil Babka <[email protected]>
Reviewed-by: Daniel Jordan <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Jason Gunthorpe <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: John Hubbard <[email protected]>
Cc: Laurent Dufour <[email protected]>
Cc: Liam Howlett <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Ying Han <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

mm/mempolicy: check hugepage migration is supported by arch in vma_migratable()

vma_migratable() is called to check if pages in vma can be migrated before
go ahead to further actions. Currently it

mm/mempolicy: check hugepage migration is supported by arch in vma_migratable()

vma_migratable() is called to check if pages in vma can be migrated before
go ahead to further actions. Currently it is used in below code path:

- task_numa_work
- mbind
- move_pages

For hugetlb mapping, whether vma is migratable or not is determined by:
- CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
- arch_hugetlb_migration_supported

Issue: current code only checks for CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
alone, and no code should use it directly. (note that current code in
vma_migratable don't cause failure or bug because
unmap_and_move_huge_page() will catch unsupported hugepage and handle it
properly)

This patch checks the two factors by hugepage_migration_supported for
impoving code logic and robustness. It will enable early bail out of
hugepage migration procedure, but because currently all architecture
supporting hugepage migration is able to support all page size, we would
not see performance gain with this patch applied.

vma_migratable() is moved to mm/mempolicy.c, because of the circular
reference of mempolicy.h and hugetlb.h cause defining it as inline not
feasible.

Signed-off-by: Li Xinhai <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Reviewed-by: Mike Kravetz <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Naoya Horiguchi <[email protected]>
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

Revert "Revert "mm, thp: restore node-local hugepage allocations""

This reverts commit a8282608c88e08b1782141026eab61204c1e533f.

The commit references the original intended semantic for MADV_HUGEPA

Revert "Revert "mm, thp: restore node-local hugepage allocations""

This reverts commit a8282608c88e08b1782141026eab61204c1e533f.

The commit references the original intended semantic for MADV_HUGEPAGE
which has subsequently taken on three unique purposes:

- enables or disables thp for a range of memory depending on the system's
config (is thp "enabled" set to "always" or "madvise"),

- determines the synchronous compaction behavior for thp allocations at
fault (is thp "defrag" set to "always", "defer+madvise", or "madvise"),
and

- reverts a previous MADV_NOHUGEPAGE (there is no madvise mode to only
clear previous hugepage advice).

These are the three purposes that currently exist in 5.2 and over the
past several years that userspace has been written around. Adding a
NUMA locality preference adds a fourth dimension to an already conflated
advice mode.

Based on the semantic that MADV_HUGEPAGE has provided over the past
several years, there exist workloads that use the tunable based on these
principles: specifically that the allocation should attempt to
defragment a local node before falling back. It is agreed that remote
hugepages typically (but not always) have a better access latency than
remote native pages, although on Naples this is at parity for
intersocket.

The revert commit that this patch reverts allows hugepage allocation to
immediately allocate remotely when local memory is fragmented. This is
contrary to the semantic of MADV_HUGEPAGE over the past several years:
that is, memory compaction should be attempted locally before falling
back.

The performance degradation of remote hugepages over local hugepages on
Rome, for example, is 53.5% increased access latency. For this reason,
the goal is to revert back to the 5.2 and previous behavior that would
attempt local defragmentation before falling back. With the patch that
is reverted by this patch, we see performance degradations at the tail
because the allocator happily allocates the remote hugepage rather than
even attempting to make a local hugepage available.

zone_reclaim_mode is not a solution to this problem since it does not
only impact hugepage allocations but rather changes the memory
allocation strategy for *all* page allocations.

Signed-off-by: David Rientjes <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Stefan Priebe - Profihost AG <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

Revert "mm, thp: restore node-local hugepage allocations"

This reverts commit 2f0799a0ffc033b ("mm, thp: restore node-local
hugepage allocations").

commit 2f0799a0ffc033b was rightfully applied to

Revert "mm, thp: restore node-local hugepage allocations"

This reverts commit 2f0799a0ffc033b ("mm, thp: restore node-local
hugepage allocations").

commit 2f0799a0ffc033b was rightfully applied to avoid the risk of a
severe regression that was reported by the kernel test robot at the end
of the merge window. Now we understood the regression was a false
positive and was caused by a significant increase in fairness during a
swap trashing benchmark. So it's safe to re-apply the fix and continue
improving the code from there. The benchmark that reported the
regression is very useful, but it provides a meaningful result only when
there is no significant alteration in fairness during the workload. The
removal of __GFP_THISNODE increased fairness.

__GFP_THISNODE cannot be used in the generic page faults path for new
memory allocations under the MPOL_DEFAULT mempolicy, or the allocation
behavior significantly deviates from what the MPOL_DEFAULT semantics are
supposed to be for THP and 4k allocations alike.

Setting THP defrag to "always" or using MADV_HUGEPAGE (with THP defrag
set to "madvise") has never meant to provide an implicit MPOL_BIND on
the "current" node the task is running on, causing swap storms and
providing a much more aggressive behavior than even zone_reclaim_node =
3.

Any workload who could have benefited from __GFP_THISNODE has now to
enable zone_reclaim_mode=1||2||3. __GFP_THISNODE implicitly provided
the zone_reclaim_mode behavior, but it only did so if THP was enabled:
if THP was disabled, there would have been no chance to get any 4k page
from the current node if the current node was full of pagecache, which
further shows how this __GFP_THISNODE was misplaced in MADV_HUGEPAGE.
MADV_HUGEPAGE has never been intended to provide any zone_reclaim_mode
semantics, in fact the two are orthogonal, zone_reclaim_mode = 1|2|3
must work exactly the same with MADV_HUGEPAGE set or not.

The performance characteristic of memory depends on the hardware
details. The numbers below are obtained on Naples/EPYC architecture and
the N/A projection extends them to show what we should aim for in the
future as a good THP NUMA locality default. The benchmark used
exercises random memory seeks (note: the cost of the page faults is not
part of the measurement).

D0 THP | D0 4k | D1 THP | D1 4k | D2 THP | D2 4k | D3 THP | D3 4k | ...
0% | +43% | +45% | +106% | +131% | +224% | N/A | N/A

D0 means distance zero (i.e. local memory), D1 means distance one (i.e.
intra socket memory), D2 means distance two (i.e. inter socket memory),
etc...

For the guest physical memory allocated by qemu and for guest mode
kernel the performance characteristic of RAM is more complex and an
ideal default could be:

D0 THP | D1 THP | D0 4k | D2 THP | D1 4k | D3 THP | D2 4k | D3 4k | ...
0% | +58% | +101% | N/A | +222% | N/A | N/A | N/A

NOTE: the N/A are projections and haven't been measured yet, the
measurement in this case is done on a 1950x with only two NUMA nodes.
The THP case here means THP was used both in the host and in the guest.

After applying this commit the THP NUMA locality order that we'll get
out of MADV_HUGEPAGE is this:

D0 THP | D1 THP | D2 THP | D3 THP | ... | D0 4k | D1 4k | D2 4k | D3 4k | ...

Before this commit it was:

D0 THP | D0 4k | D1 4k | D2 4k | D3 4k | ...

Even if we ignore the breakage of large workloads that can't fit in a
single node that the __GFP_THISNODE implicit "current node" mbind
caused, the THP NUMA locality order provided by __GFP_THISNODE was still
not the one we shall aim for in the long term (i.e. the first one at
the top).

After this commit is applied, we can introduce a new allocator multi
order API and to replace those two alloc_pages_vmas calls in the page
fault path, with a single multi order call:

unsigned int order = (1 << HPAGE_PMD_ORDER) | (1 << 0);
page = alloc_pages_multi_order(..., &order);
if (!page)
goto out;
if (!(order & (1 << 0))) {
VM_WARN_ON(order != 1 << HPAGE_PMD_ORDER);
/* THP fault */
} else {
VM_WARN_ON(order != 1 << 0);
/* 4k fallback */
}

The page allocator logic has to be altered so that when it fails on any
zone with order 9, it has to try again with a order 0 before falling
back to the next zone in the zonelist.

After that we need to do more measurements and evaluate if adding an
opt-in feature for guest mode is worth it, to swap "DN 4k | DN+1 THP"
with "DN+1 THP | DN 4k" at every NUMA distance crossing.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Andrea Arcangeli <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Acked-by: Mel Gorman <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Zi Yan <[email protected]>
Cc: Stefan Priebe - Profihost AG <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

mm, thp: restore node-local hugepage allocations

This is a full revert of ac5b2c18911f ("mm: thp: relax __GFP_THISNODE for
MADV_HUGEPAGE mappings") and a partial revert of 89c83fb539f9 ("mm, thp:
co

mm, thp: restore node-local hugepage allocations

This is a full revert of ac5b2c18911f ("mm: thp: relax __GFP_THISNODE for
MADV_HUGEPAGE mappings") and a partial revert of 89c83fb539f9 ("mm, thp:
consolidate THP gfp handling into alloc_hugepage_direct_gfpmask").

By not setting __GFP_THISNODE, applications can allocate remote hugepages
when the local node is fragmented or low on memory when either the thp
defrag setting is "always" or the vma has been madvised with
MADV_HUGEPAGE.

Remote access to hugepages often has much higher latency than local pages
of the native page size. On Haswell, ac5b2c18911f was shown to have a
13.9% access regression after this commit for binaries that remap their
text segment to be backed by transparent hugepages.

The intent of ac5b2c18911f is to address an issue where a local node is
low on memory or fragmented such that a hugepage cannot be allocated. In
every scenario where this was described as a fix, there is abundant and
unfragmented remote memory available to allocate from, even with a greater
access latency.

If remote memory is also low or fragmented, not setting __GFP_THISNODE was
also measured on Haswell to have a 40% regression in allocation latency.

Restore __GFP_THISNODE for thp allocations.

Fixes: ac5b2c18911f ("mm: thp: relax __GFP_THISNODE for MADV_HUGEPAGE mappings")
Fixes: 89c83fb539f9 ("mm, thp: consolidate THP gfp handling into alloc_hugepage_direct_gfpmask")
Cc: Andrea Arcangeli <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Andrew Morton <[email protected]>
Signed-off-by: David Rientjes <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

mm, thp: consolidate THP gfp handling into alloc_hugepage_direct_gfpmask

THP allocation mode is quite complex and it depends on the defrag mode.
This complexity is hidden in alloc_hugepage_direct_gf

mm, thp: consolidate THP gfp handling into alloc_hugepage_direct_gfpmask

THP allocation mode is quite complex and it depends on the defrag mode.
This complexity is hidden in alloc_hugepage_direct_gfpmask from a large
part currently. The NUMA special casing (namely __GFP_THISNODE) is
however independent and placed in alloc_pages_vma currently. This both
adds an unnecessary branch to all vma based page allocation requests and
it makes the code more complex unnecessarily as well. Not to mention
that e.g. shmem THP used to do the node reclaiming unconditionally
regardless of the defrag mode until recently. This was not only
unexpected behavior but it was also hardly a good default behavior and I
strongly suspect it was just a side effect of the code sharing more than
a deliberate decision which suggests that such a layering is wrong.

Get rid of the thp special casing from alloc_pages_vma and move the
logic to alloc_hugepage_direct_gfpmask. __GFP_THISNODE is applied to the
resulting gfp mask only when the direct reclaim is not requested and
when there is no explicit numa binding to preserve the current logic.

Please note that there's also a slight difference wrt MPOL_BIND now. The
previous code would avoid using __GFP_THISNODE if the local node was
outside of policy_nodemask(). After this patch __GFP_THISNODE is avoided
for all MPOL_BIND policies. So there's a difference that if local node
is actually allowed by the bind policy's nodemask, previously
__GFP_THISNODE would be added, but now it won't be. From the behavior
POV this is still correct because the policy nodemask is used.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Michal Hocko <[email protected]>
Acked-by: Vlastimil Babka <[email protected]>
Cc: Alex Williamson <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Stefan Priebe - Profihost AG <[email protected]>
Cc: Zi Yan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine

License cleanup: add SPDX GPL-2.0 license identifier to files with no license

Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.

By default all files without license information are under the default
license of the kernel, which is GPL version 2.

Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.

This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.

How this work was done:

Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,

Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.

The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.

The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.

Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).

All documentation files were explicitly excluded.

The following heuristics were used to determine which SPDX license
identifiers to apply.

- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.

For non */uapi/* files that summary was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139

and resulted in the first patch in this series.

If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:

SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930

and resulted in the second patch in this series.

- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:

SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1

and that resulted in the third patch in this series.

- when the two scanners agreed on the detected license(s), that became
the concluded license(s).

- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.

- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).

- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.

- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.

In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.

Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.

Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.

In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.

Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct

This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.

These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.

Reviewed-by: Kate Stewart <[email protected]>
Reviewed-by: Philippe Ombredanne <[email protected]>
Reviewed-by: Thomas Gleixner <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>

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mm, mempolicy: simplify rebinding mempolicies when updating cpusets

Commit c0ff7453bb5c ("cpuset,mm: fix no node to alloc memory when
changing cpuset's mems") has introduced a two-step protocol when

mm, mempolicy: simplify rebinding mempolicies when updating cpusets

Commit c0ff7453bb5c ("cpuset,mm: fix no node to alloc memory when
changing cpuset's mems") has introduced a two-step protocol when
rebinding task's mempolicy due to cpuset update, in order to avoid a
parallel allocation seeing an empty effective nodemask and failing.

Later, commit cc9a6c877661 ("cpuset: mm: reduce large amounts of memory
barrier related damage v3") introduced a seqlock protection and removed
the synchronization point between the two update steps. At that point
(or perhaps later), the two-step rebinding became unnecessary.

Currently it only makes sure that the update first adds new nodes in
step 1 and then removes nodes in step 2. Without memory barriers the
effects are questionable, and even then this cannot prevent a parallel
zonelist iteration checking the nodemask at each step to observe all
nodes as unusable for allocation. We now fully rely on the seqlock to
prevent premature OOMs and allocation failures.

We can thus remove the two-step update parts and simplify the code.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Vlastimil Babka <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: "Kirill A. Shutemov" <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Anshuman Khandual <[email protected]>
Cc: Christoph Lameter <[email protected]>
Cc: David Rientjes <[email protected]>
Cc: Dimitri Sivanich <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Li Zefan <[email protected]>
Cc: Mel Gorman <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

show more ...