This adds support for allowing proactive reclaim in general on a NUMA
system. A per-node interface extends support for beyond a memcg-specific
interface, respecting the current semantics of memory.reclaim: respecting
aging LRU and not supporting artificially triggering eviction on nodes
belonging to non-bottom tiers.
This patch allows userspace to do:
echo "512M swappiness=10" > /sys/devices/system/node/nodeX/reclaim
One of the premises for this is to semantically align as best as possible
with memory.reclaim. During a brief time memcg did support nodemask until
55ab834a86 (Revert "mm: add nodes= arg to memory.reclaim"), for which
semantics around reclaim (eviction) vs demotion were not clear, rendering
charging expectations to be broken.
With this approach:
1. Users who do not use memcg can benefit from proactive reclaim. The
memcg interface is not NUMA aware and there are usecases that are
focusing on NUMA balancing rather than workload memory footprint.
2. Proactive reclaim on top tiers will trigger demotion, for which
memory is still byte-addressable. Reclaiming on the bottom nodes will
trigger evicting to swap (the traditional sense of reclaim). This
follows the semantics of what is today part of the aging process on
tiered memory, mirroring what every other form of reclaim does
(reactive and memcg proactive reclaim). Furthermore per-node proactive
reclaim is not as susceptible to the memcg charging problem mentioned
above.
3. Unlike the nodes= arg, this interface avoids confusing semantics,
such as what exactly the user wants when mixing top-tier and low-tier
nodes in the nodemask. Further per-node interface is less exposed to
"free up memory in my container" usecases, where eviction is intended.
4. Users that *really* want to free up memory can use proactive
reclaim on nodes knowingly to be on the bottom tiers to force eviction
in a natural way - higher access latencies are still better than swap.
If compelled, while no guarantees and perhaps not worth the effort,
users could also also potentially follow a ladder-like approach to
eventually free up the memory. Alternatively, perhaps an 'evict'
option could be added to the parameters for both memory.reclaim and
per-node interfaces to force this action unconditionally.
[akpm@linux-foundation.org: user_proactive_reclaim(): return -EBUSY on PGDAT_RECLAIM_LOCKED contention, per Roman]
[dave@stgolabs.net: memcg && node is also a bogus case, per Shakeel]
Link: https://lkml.kernel.org/r/20250717235604.2atyx2aobwowpge3@offworld
Link: https://lkml.kernel.org/r/20250623185851.830632-5-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm: per-node proactive reclaim", v2.
This adds support for allowing proactive reclaim in general on a NUMA
system. A per-node interface extends support for beyond a memcg-specific
interface, respecting the current semantics of memory.reclaim: respecting
aging LRU and not supporting artificially triggering eviction on nodes
belonging to non-bottom tiers.
This patch allows userspace to do:
echo 512M swappiness=10 > /sys/devices/system/node/nodeX/reclaim
One of the premises for this is to semantically align as best as possible
with memory.reclaim. During a brief time memcg did support nodemask until
55ab834a86 (Revert "mm: add nodes= arg to memory.reclaim"), for which
semantics around reclaim (eviction) vs demotion were not clear, rendering
charging expectations to be broken.
With this approach:
1. Users who do not use memcg can benefit from proactive reclaim.
2. Proactive reclaim on top tiers will trigger demotion, for which
memory is still byte-addressable. Reclaiming on the bottom nodes will
trigger evicting to swap (the traditional sense of reclaim). This
follows the semantics of what is today part of the aging process on
tiered memory, mirroring what every other form of reclaim does
(reactive and memcg proactive reclaim). Furthermore per-node proactive
reclaim is not as susceptible to the memcg charging problem mentioned
above.
3. Unlike memcg, there should be no surprises of callers expecting
reclaim but instead got a demotion. Essentially relying on behavior of
shrink_folio_list() after 6b426d0714 ("mm: disable top-tier fallback
to reclaim on proactive reclaim"), without the expectations of
try_to_free_mem_cgroup_pages().
4. Unlike the nodes= arg, this interface avoids confusing semantics,
such as what exactly the user wants when mixing top-tier and low-tier
nodes in the nodemask. Further per-node interface is less exposed to
"free up memory in my container" usecases, where eviction is intended.
5. Users that *really* want to free up memory can use proactive
reclaim on nodes knowingly to be on the bottom tiers to force eviction
in a natural way - higher access latencies are still better than swap.
If compelled, while no guarantees and perhaps not worth the effort,
users could also also potentially follow a ladder-like approach to
eventually free up the memory. Alternatively, perhaps an 'evict'
option could be added to the parameters for both memory.reclaim and
per-node interfaces to force this action unconditionally.
This patch (of 4):
... rather benign but keep proper ending order.
Link: https://lkml.kernel.org/r/20250623185851.830632-1-dave@stgolabs.net
Link: https://lkml.kernel.org/r/20250623185851.830632-2-dave@stgolabs.net
Signed-off-by: Davidlohr Bueso <dave@stgolabs.net>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The paddr versions of migrate_{hot/cold} filter out folios from migration
based on the scheme's filters. This patch does the same for the vaddr
versions of those schemes.
The filtering code is mostly the same for the paddr and vaddr versions.
The exception is the young filter. paddr determines if a page is young by
doing a folio rmap walk to find the page table entries corresponding to
the folio. However, vaddr schemes have easier access to the page tables,
so we add some logic to avoid the extra work.
Link: https://lkml.kernel.org/r/20250709005952.17776-14-bijan311@gmail.com
Co-developed-by: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Bijan Tabatabai <bijantabatab@micron.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
damos->migrate_dests provides a list of nodes the migrate_{hot,cold}
actions should migrate to, as well as the weights which specify the ratio
pages should be migrated to each destination node.
This patch interleaves pages in the migrate_{hot,cold} actions according
to the information provided in damos->migrate_dests if it is used. The
interleaving algorithm used is similar to the one used in
weighted_interleave_nid(). If damos->migration_dests is not provided, the
actions migrate pages to the node specified in damos->target_nid as
before.
Link: https://lkml.kernel.org/r/20250709005952.17776-12-bijan311@gmail.com
Co-developed-by: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Bijan Tabatabai <bijantabatab@micron.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
DAMOS_MIGRATE_{HOT,COLD} can have multiple action destinations and their
weights. Implement sysfs directory named 'dests' under each scheme
directory to let DAMON sysfs ABI users utilize the feature. The interface
is similar to other multiple parameters directory like kdamonds or
filters. The directory contains only nr_dests file initially. Writing a
number of desired destinations to nr_dests creates directories of the
number. Each of the created directories has two files named id and
weight. Users can then write the destination's identifier (node id in
case of DAMOS_MIGRATE_*) and weight to the files.
Link: https://lkml.kernel.org/r/20250709005952.17776-4-bijan311@gmail.com
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Bijan Tabatabai <bijantabatab@micron.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm/damon/vaddr: Allow interleaving in migrate_{hot,cold}
actions", v4.
A recent patchset automatically sets the interleave weight for each node
according to the node's maximum bandwidth [1]. In another thread, the
patch set's author, Joshua Hahn, wondered if/how thes weights should be
changed if the bandwidth utilization of the system changes [2].
This patch set adds the mechanism for dynamically changing how application
data is interleaved across nodes while leaving the policy of what the
interleave weights should be to userspace. It does this by having the
migrate_{hot,cold} operating schemes interleave application data according
to the list of migration nodes and weights passed in via the DAMON sysfs
interface. This functionality can be used to dynamically adjust how
folios are interleaved by having a userspace process adjust those weights.
If no specific destination nodes or weights are provided, the
migrate_{hot,cold} actions will only migrate folios to damos->target_nid
as before.
The algorithm used to interleave the folios is similar to the one used for
the weighted interleave mempolicy [3]. It uses the offset from which a
folio is mapped into a VMA to determine the node the folio should be
placed in. This method is convenient because for a given set of
interleave weights, a folio has only one valid node it can be placed in,
limitng the amount of unnecessary data movement. However, finding out how
a folio is mapped inside of a VMA requires a costly rmap walk when using a
paddr scheme. As such, we have decided that this functionality makes more
sense as a vaddr scheme [4]. To this end, this patch set also adds vaddr
versions of the migrate_{hot,cold}.
Motivation
==========
There have been prior discussions about how changing the interleave
weights in response to the system's bandwidth utilization can be
beneficial [2]. However, currently the interleave weights only are
applied when data is allocated. Migrating already allocated pages
according to the dynamically changing weights will better help balance the
bandwidth utilization across nodes.
As a toy example, imagine some application that uses 75% of the local
bandwidth. Assuming sufficient capacity, when running alone, we want to
keep that application's data in local memory. However, if a second
instance of that application begins, using the same amount of bandwidth,
it would be best to interleave the data of both processes to alleviate the
bandwidth pressure from the local node. Likewise, when one of the
processes ends, the data should be moves back to local memory.
We imagine there would be a userspace application that would monitor
system performance characteristics, such as bandwidth utilization or
memory access latency, and uses that information to tune the interleave
weights. Others seem to have come to a similar conclusion in previous
discussions [5]. We are currently working on a userspace program that
does this, but it is not quite ready to be published yet.
After the userspace application tunes the interleave weights, there must
be some mechanism that actually migrates pages to be consistent with those
weights. This patchset is what provides this mechanism.
We believe DAMON is the correct venue for the interleaving mechanism for a
few reasons. First, we noticed that we don't have to migrate all of the
application's pages to improve performance. we just need to migrate the
frequently accessed pages. DAMON's existing hotness traching is very
useful for this. Second, DAMON's quota system can be used to ensure we
are not using too much bandwidth for migrations. Finally, as Ying pointed
out [6], a complete solution must also handle when a memory node is at
capacity. The existing migrate_cold action can be used in conjunction
with the functionality added in this patch set to provide that complete
solution.
Functionality Test
==================
Below is an example of this new functionality in use to confirm that these
patches behave as intended.
In this example, the user starts an application, alloc_data, which
allocates 1GB using the default memory policy (i.e. allocate to local
memory) then sleeps. Afterwards, we start DAMON to interleave the data at
a 1:1 ratio. Using numastat, we show that DAMON has migrated the
application's data to match the new interleave ratio.
For this example, I modified the userspace damo tool [8] to write to the
migration_dest sysfs files. I plan to upstream these changes when these
patches are merged.
$ # Allocate the data initially
$ ./alloc_data 1G &
[1] 6587
$ numastat -c -p alloc_data
Per-node process memory usage (in MBs) for PID 6587 (alloc_data)
Node 0 Node 1 Total
------ ------ -----
Huge 0 0 0
Heap 0 0 0
Stack 0 0 0
Private 1027 0 1027
------- ------ ------ -----
Total 1027 0 1027
$ # Start DAMON to interleave data at a 1:1 ratio
$ cat ./interleave_vaddr.yaml
kdamonds:
- contexts:
- ops: vaddr
addr_unit: null
targets:
- pid: 6587
regions: []
intervals:
sample_us: 500 ms
aggr_us: 5 s
ops_update_us: 20 s
intervals_goal:
access_bp: 0 %
aggrs: '0'
min_sample_us: 0 ns
max_sample_us: 0 ns
nr_regions:
min: '20'
max: '50'
schemes:
- action: migrate_hot
dests:
- nid: 0
weight: 1
- nid: 1
weight: 1
access_pattern:
sz_bytes:
min: 0 B
max: max
nr_accesses:
min: 0 %
max: 100 %
age:
min: 0 ns
max: max
$ sudo ./damo/damo interleave_vaddr.yaml
$ # Verify that DAMON has migrated data to match the 1:1 ratio
$ numastat -c -p alloc_data
Per-node process memory usage (in MBs) for PID 6587 (alloc_data)
Node 0 Node 1 Total
------ ------ -----
Huge 0 0 0
Heap 0 0 0
Stack 0 0 0
Private 514 514 1027
------- ------ ------ -----
Total 514 514 1027
Performance Test
================
Below is a simple example showing that interleaving application data using
these patches can improve application performance. To do this, we run a
bandwidth intensive embedding reduction application [7]. This workload is
useful for this test because it reports the time it takes each iteration
to run and each iteration reuses the same allocation, allowing us to see
the benefits of the migration.
We evaluate this on a 128 core/256 thread AMD CPU with 72GB/s of local DDR
bandwidth and 26 GB/s of CXL bandwidth.
Before we start the workload, the system bandwidth utilization is low, so
we start with the interleave weights of 1:0, i.e. allocating all data to
local memory. When the workload beings, it saturates the local bandwidth,
making the page placement suboptimal. To alleviate this, we modify the
interleave weights, triggering DAMON to migrate the workload's data.
We use the same interleave_vaddr.yaml file to setup DAMON, except we
configure it to begin with a 1:0 interleave ratio, and attach it to the
shell and its children processes.
$ sudo ./damo/damo start interleave_vaddr.yaml --include_child_tasks &
$ <path>/eval_baseline -d amazon_All -c 255 -r 100
<clip startup output>
Eval Phase 3: Running Baseline...
REPEAT # 0 Baseline Total time : 7323.54 ms
REPEAT # 1 Baseline Total time : 7624.56 ms
REPEAT # 2 Baseline Total time : 7619.61 ms
REPEAT # 3 Baseline Total time : 7617.12 ms
REPEAT # 4 Baseline Total time : 7638.64 ms
REPEAT # 5 Baseline Total time : 7611.27 ms
REPEAT # 6 Baseline Total time : 7629.32 ms
REPEAT # 7 Baseline Total time : 7695.63 ms
# Interleave weights set to 3:1
REPEAT # 8 Baseline Total time : 7077.5 ms
REPEAT # 9 Baseline Total time : 5633.23 ms
REPEAT # 10 Baseline Total time : 5644.6 ms
REPEAT # 11 Baseline Total time : 5627.66 ms
REPEAT # 12 Baseline Total time : 5629.76 ms
REPEAT # 13 Baseline Total time : 5633.05 ms
REPEAT # 14 Baseline Total time : 5641.24 ms
REPEAT # 15 Baseline Total time : 5631.18 ms
REPEAT # 16 Baseline Total time : 5631.33 ms
Updating the interleave weights and having DAMON migrate the workload data
according to the weights resulted in an approximarely 25% speedup.
Patches Sequence
================
Patches 1-7 extend the DAMON API to specify multiple destination nodes and
weights for the migrate_{hot,cold} actions. These patches are from SJ'S
RFC [8].
Patches 8-10 add a vaddr implementation of the migrate_{hot,cold} schemes.
Patch 11 modifies the vaddr migrate_{hot,cold} schemes to interleave data
according to the weights provided by damos->migrate_dest.
Patches 12-13 allow the vaddr migrate_{hot,cold} implementation to filter
out folios like the paddr version.
This patch (of 13):
Introduce a new struct, namely damos_migrate_dests, for specifying
multiple DAMOS' migration destination nodes and their weights.
Link: https://lkml.kernel.org/r/20250709005952.17776-1-bijan311@gmail.com
Link: https://lkml.kernel.org/r/20250709005952.17776-2-bijan311@gmail.com
Link: https://lore.kernel.org/linux-mm/20250520141236.2987309-1-joshua.hahnjy@gmail.com/ [1]
Link: https://lore.kernel.org/linux-mm/20250313155705.1943522-1-joshua.hahnjy@gmail.com/ [2]
Link: https://elixir.bootlin.com/linux/v6.15.4/source/mm/mempolicy.c#L2015 [3]
Link: https://lore.kernel.org/damon/20250624223310.55786-1-sj@kernel.org/ [4]
Link: https://lore.kernel.org/linux-mm/20250314151137.892379-1-joshua.hahnjy@gmail.com/ [5]
Link: https://lore.kernel.org/linux-mm/87frjfx6u4.fsf@DESKTOP-5N7EMDA/ [6]
Link: https://github.com/SNU-ARC/MERCI [7]
Link: https://lore.kernel.org/damon/20250702051558.54138-1-sj@kernel.org/ [8]
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Bijan Tabatabai <bijantabatab@micron.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Ravi Shankar Jonnalagadda <ravis.opensrc@micron.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This patch adds a new knob `detect_node_addresses`, which determines
whether the physical address range is set manually using the existing
knobs or automatically by the mtier module. When `detect_node_addresses`
set to 'Y', mtier automatically converts node0 and node1 to their physical
addresses. If set to 'N', it uses the existing 'node#_start_addr' and
'node#_end_addr' to define regions as before.
Link: https://lkml.kernel.org/r/20250707235919.513-1-yunjeong.mun@sk.com
Signed-off-by: Yunjeong Mun <yunjeong.mun@sk.com>
Suggested-by: Honggyu Kim <honggyu.kim@sk.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The damon_{lru_sort,reclaim,stat} kernel modules use "enabled" parameter
knobs as follows.
/sys/module/damon_lru_sort/parameters/enabled
/sys/module/damon_reclaim/parameters/enabled
/sys/module/damon_stat/parameters/enabled
However, other sample modules of damon use "enable" parameter knobs so
it'd be better to rename them from "enable" to "enabled" to keep the
consistency with other damon modules.
Before:
/sys/module/damon_sample_wsse/parameters/enable
/sys/module/damon_sample_prcl/parameters/enable
/sys/module/damon_sample_mtier/parameters/enable
After:
/sys/module/damon_sample_wsse/parameters/enabled
/sys/module/damon_sample_prcl/parameters/enabled
/sys/module/damon_sample_mtier/parameters/enabled
There is no functional changes in this patch.
Link: https://lkml.kernel.org/r/20250707024548.1964-1-honggyu.kim@sk.com
Signed-off-by: Honggyu Kim <honggyu.kim@sk.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The vmstat_text array contains labels for counters displayed in
/proc/vmstat. It is important to keep the labels in sync with the
counters.
There is a BUILD_BUG_ON() check in vmstat_start() that ensures the size of
the vmstat_text is not smaller than VM_EVENT_COUNTERS. This helps to
catch cases where a new counter is added but the label is not. However,
it does not help if a counter is removed but the label remains.
It would be nice to make the BUILD_BUG_ON() check more strict to catch
such cases. However, when compiling with MEMCG enabled but
VM_EVENT_COUNTERS disabled, the vmstat_text array is larger than
NR_VMSTAT_ITEMS.
This issue arises because some elements of the vmstat_text array are
present when either MEMCG or VM_EVENT_COUNTERS is enabled, but
NR_VMSTAT_ITEMS only accounts for these elements if VM_EVENT_COUNTERS is
enabled.
Instead of adjusting the NR_VMSTAT_ITEMS definition to account for MEMCG,
make MEMCG select VM_EVENT_COUNTERS. VM_EVENT_COUNTERS is enabled in most
configurations anyway.
Link: https://lkml.kernel.org/r/20250604095111.533783-1-kirill.shutemov@linux.intel.com
Fixes: ebc5d83d04 ("mm/memcontrol: use vmstat names for printing statistics")
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Many users (including upcoming ones) don't really need the flags etc, and
can live with the possible overhead of a function call.
So let's provide a basic, non-inlined folio_pte_batch(), to avoid code
bloat while still providing a variant that optimizes out all flag checks
at runtime. folio_pte_batch_flags() will get inlined into
folio_pte_batch(), optimizing out any conditionals that depend on input
flags.
folio_pte_batch() will behave like folio_pte_batch_flags() when no flags
are specified. It's okay to add new users of folio_pte_batch_flags(), but
using folio_pte_batch() if applicable is preferred.
So, before this change, folio_pte_batch() was inlined into the C file
optimized by propagating constants within the resulting object file.
With this change, we now also have a folio_pte_batch() that is optimized
by propagating all constants. But instead of having one instance per
object file, we have a single shared one.
In zap_present_ptes(), where we care about performance, the compiler
already seem to generate a call to a common inlined folio_pte_batch()
variant, shared with fork() code. So calling the new non-inlined variant
should not make a difference.
While at it, drop the "addr" parameter that is unused.
Link: https://lkml.kernel.org/r/20250702104926.212243-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/linux-mm/20250503182858.5a02729fcffd6d4723afcfc2@linux-foundation.org/
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm: folio_pte_batch() improvements", v2.
Ever since we added folio_pte_batch() for fork() + munmap() purposes, a
lot more users appeared (and more are being proposed), and more
functionality was added.
Most of the users only need basic functionality, and could benefit from a
non-inlined version.
So let's clean up folio_pte_batch() and split it into a basic
folio_pte_batch() (no flags) and a more advanced folio_pte_batch_ext().
Using either variant will now look much cleaner.
This series will likely conflict with some changes in some (old+new)
folio_pte_batch() users, but conflicts should be trivial to resolve.
This patch (of 4):
Respecting these PTE bits is the exception, so let's invert the meaning.
With this change, most callers don't have to pass any flags. This is a
preparation for splitting folio_pte_batch() into a non-inlined variant
that doesn't consume any flags.
Long-term, we want folio_pte_batch() to probably ignore most common PTE
bits (e.g., write/dirty/young/soft-dirty) that are not relevant for most
page table walkers: uffd-wp and protnone might be bits to consider in the
future. Only walkers that care about them can opt-in to respect them.
No functional change intended.
Link: https://lkml.kernel.org/r/20250702104926.212243-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
damon_sysfs_before_terminate() is a DAMON callback that is executed from
the kdamond's context. Hence it is safe to access DAMON context internal
data. But the function is unnecessarily holding kdamond_lock of the
context. It is just unnecessary. Remove the locking code.
Link: https://lkml.kernel.org/r/20250705175000.56259-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
DAMON sample module, mtier has its name 'mtier'. It could conflict with
future modules, and not very easy to identify it by name. Use a prefix,
"damon_sample_" for the name.
Note that this could break users if they depend on the old name. But it
is just a sample, so no such usage is expected, or known. Even if such
usage exists, updating it for the new name should be straightforward.
Link: https://lkml.kernel.org/r/20250705175000.56259-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
DAMON sample module, prcl has its name 'prcl'. It could conflict with
future modules, and not very easy to identify it by name. Use a prefix,
"damon_sample_" for the name.
Note that this could break users if they depend on the old name. But it
is just a sample, so no such usage is expected, or known. Even if such
usage exists, updating it for the new name should be straightforward.
Link: https://lkml.kernel.org/r/20250705175000.56259-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm/damon: misc cleanups".
Yet another round of miscellaneous DAMON cleanups.
This patch (of 6):
DAMON sample module, wsse has its name 'wsse'. It could conflict with
future modules, and not very easy to identify it by name. Use a prefix,
"damon_sample_" for the name.
Note that this could break users if they depend on the old name. But it
is just a sample, so no such usage is expected, or known. Even if such
usage exists, updating it for the new name should be straightforward.
Link: https://lkml.kernel.org/r/20250705175000.56259-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20250705175000.56259-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
After commit acd7ccb284 ("mm: shmem: add large folio support for
tmpfs"), tmpfs can also support large folio allocation (not just PMD-sized
large folios).
However, when accessing tmpfs via mmap(), although tmpfs supports large
folios, we still establish mappings at the base page granularity, which is
unreasonable.
We can map multiple consecutive pages of tmpfs folios at once according to
the size of the large folio. On one hand, this can reduce the overhead of
page faults; on the other hand, it can leverage hardware architecture
optimizations to reduce TLB misses, such as contiguous PTEs on the ARM
architecture.
Moreover, tmpfs mount will use the 'huge=' option to control large folio
allocation explicitly. So it can be understood that the process's RSS
statistics might increase, and I think this will not cause any obvious
effects for users.
Performance test:
I created a 1G tmpfs file, populated with 64K large folios, and write-accessed it
sequentially via mmap(). I observed a significant performance improvement:
Before the patch:
real 0m0.158s
user 0m0.008s
sys 0m0.150s
After the patch:
real 0m0.021s
user 0m0.004s
sys 0m0.017s
Link: https://lkml.kernel.org/r/440940e78aeb7430c5cc8b6d2088ae98265b9809.1751599072.git.baolin.wang@linux.alibaba.com
Fixes: acd7ccb284 ("mm: shmem: add large folio support for tmpfs")
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
damon_reclaim_apply_parameters() allocates a new DAMON context, stages
user-specified DAMON parameters on it, and commits to running DAMON
context at once, using damon_commit_ctx(). The code is mistakenly
over-writing the monitoring attributes and the reclaim scheme on the
running context. It is not causing a real problem for monitoring
attributes, but the scheme overwriting can remove scheme's internal status
such as charged quota. Fix the wrong use of the parameter context.
Link: https://lkml.kernel.org/r/20250706193207.39810-7-sj@kernel.org
Fixes: 11ddcfc257 ("mm/damon/reclaim: use damon_commit_ctx()")
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When the startup fails, 'enabled' parameter is not reset. As a result,
users show the parameter 'Y' while it is not really working. Fix it by
resetting 'enabled' to 'false' when the work is failed.
Link: https://lkml.kernel.org/r/20250706193207.39810-6-sj@kernel.org
Fixes: 7a034fbba3 ("mm/damon/lru_sort: enable and disable synchronously")
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When the startup fails, 'enabled' parameter is not reset. As a result,
users show the parameter 'Y' while it is not really working. Fix it by
resetting 'enabled' to 'false' when the work is failed.
Link: https://lkml.kernel.org/r/20250706193207.39810-5-sj@kernel.org
Fixes: 04e98764be ("mm/damon/reclaim: enable and disable synchronously")
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
If 'enable' parameter of the 'mtier' DAMON sample module is set at boot
time via the kernel command line, memory allocation is tried before the
slab is initialized. As a result kernel NULL pointer dereference BUG can
happen. Fix it by checking the initialization status.
Link: https://lkml.kernel.org/r/20250706193207.39810-4-sj@kernel.org
Fixes: 82a08bde3c ("samples/damon: implement a DAMON module for memory tiering")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
If 'enable' parameter of the 'prcl' DAMON sample module is set at boot
time via the kernel command line, memory allocation is tried before the
slab is initialized. As a result kernel NULL pointer dereference BUG can
happen. Fix it by checking the initialization status.
Link: https://lkml.kernel.org/r/20250706193207.39810-3-sj@kernel.org
Fixes: 2aca254620 ("samples/damon: introduce a skeleton of a smaple DAMON module for proactive reclamation")
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm/damon: fix misc bugs in DAMON modules".
From manual code review, I found below bugs in DAMON modules.
DAMON sample modules crash if those are enabled at boot time, via kernel
command line. A similar issue was found and fixed on DAMON non-sample
modules in the past, but we didn't check that for sample modules.
DAMON non-sample modules are not setting 'enabled' parameters accordingly
when real enabling is failed. Honggyu found and fixed[1] this type of
bugs in DAMON sample modules, and my inspection was motivated by the great
work. Kudos to Honggyu.
Finally, DAMON_RECLIAM is mistakenly losing scheme internal status due to
misuse of damon_commit_ctx(). DAMON_LRU_SORT has a similar misuse, but
fortunately it is not causing real status loss.
Fix the bugs. Since these are similar patterns of bugs that were found in
the past, it would be better to add tests or refactor the code, in future.
This patch (of 6):
If 'enable' parameter of the 'wsse' DAMON sample module is set at boot
time via the kernel command line, memory allocation is tried before the
slab is initialized. As a result kernel NULL pointer dereference BUG can
happen. Fix it by checking the initialization status.
Link: https://lkml.kernel.org/r/20250706193207.39810-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20250706193207.39810-2-sj@kernel.org
Link: https://lore.kernel.org/20250702000205.1921-1-honggyu.kim@sk.com [1]
Fixes: b757c6cfc6 ("samples/damon/wsse: start and stop DAMON as the user requests")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
