Reduce 22 declarations of empty_zero_page to 3 and 23 declarations of
ZERO_PAGE() to 4.
Every architecture defines empty_zero_page that way or another, but for the
most of them it is always a page aligned page in BSS and most definitions
of ZERO_PAGE do virt_to_page(empty_zero_page).
Move Linus vetted x86 definition of empty_zero_page and ZERO_PAGE() to the
core MM and drop these definitions in architectures that do not implement
colored zero page (MIPS and s390).
ZERO_PAGE() remains a macro because turning it to a wrapper for a static
inline causes severe pain in header dependencies.
For the most part the change is mechanical, with these being noteworthy:
* alpha: aliased empty_zero_page with ZERO_PGE that was also used for boot
parameters. Switching to a generic empty_zero_page removes the aliasing
and keeps ZERO_PGE for boot parameters only
* arm64: uses __pa_symbol() in ZERO_PAGE() so that definition of
ZERO_PAGE() is kept intact.
* m68k/parisc/um: allocated empty_zero_page from memblock,
although they do not support zero page coloring and having it in BSS
will work fine.
* sparc64 can have empty_zero_page in BSS rather allocate it, but it
can't use virt_to_page() for BSS. Keep it's definition of ZERO_PAGE()
but instead of allocating it, make mem_map_zero point to
empty_zero_page.
* sh: used empty_zero_page for boot parameters at the very early boot.
Rename the parameters page to boot_params_page and let sh use the generic
empty_zero_page.
* hexagon: had an amusing comment about empty_zero_page
/* A handy thing to have if one has the RAM. Declared in head.S */
that unfortunately had to go :)
Link: https://lkml.kernel.org/r/20260211103141.3215197-4-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Helge Deller <deller@gmx.de> [parisc]
Tested-by: Helge Deller <deller@gmx.de> [parisc]
Reviewed-by: Christophe Leroy (CS GROUP) <chleroy@kernel.org>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Magnus Lindholm <linmag7@gmail.com> [alpha]
Acked-by: Dinh Nguyen <dinguyen@kernel.org> [nios2]
Acked-by: Andreas Larsson <andreas@gaisler.com> [sparc]
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add test_zswap_incompressible() to verify that the zswap_incomp memcg stat
correctly tracks incompressible pages.
The test allocates memory filled with random data from /dev/urandom, which
cannot be effectively compressed by zswap. When this data is swapped out
to zswap, it should be stored as-is and tracked by the zswap_incomp
counter.
The test verifies that:
1. Pages are swapped out to zswap (zswpout increases)
2. Incompressible pages are tracked (zswap_incomp increases)
test:
dd if=/dev/zero of=/swapfile bs=1M count=2048
chmod 600 /swapfile
mkswap /swapfile
swapon /swapfile
echo Y > /sys/module/zswap/parameters/enabled
./test_zswap
TAP version 13
1..8
ok 1 test_zswap_usage
ok 2 test_swapin_nozswap
ok 3 test_zswapin
ok 4 test_zswap_writeback_enabled
ok 5 test_zswap_writeback_disabled
ok 6 test_no_kmem_bypass
ok 7 test_no_invasive_cgroup_shrink
ok 8 test_zswap_incompressible
Totals: pass:8 fail:0 xfail:0 xpass:0 skip:0 error:0
Link: https://lkml.kernel.org/r/20260213071827.5688-3-jiayuan.chen@linux.dev
Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Yosry Ahmed <yosry.ahmed@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm: zswap: add per-memcg stat for incompressible pages", v3.
In containerized environments, knowing which cgroup is contributing
incompressible pages to zswap is essential for effective resource
management. This series adds a new per-memcg stat 'zswap_incomp' to track
incompressible pages, along with a selftest.
This patch (of 2):
The global zswap_stored_incompressible_pages counter was added in commit
dca4437a58 ("mm/zswap: store <PAGE_SIZE compression failed page as-is")
to track how many pages are stored in raw (uncompressed) form in zswap.
However, in containerized environments, knowing which cgroup is
contributing incompressible pages is essential for effective resource
management [1].
Add a new memcg stat 'zswap_incomp' to track incompressible pages per
cgroup. This helps administrators and orchestrators to:
1. Identify workloads that produce incompressible data (e.g., encrypted
data, already-compressed media, random data) and may not benefit from
zswap.
2. Make informed decisions about workload placement - moving
incompressible workloads to nodes with larger swap backing devices
rather than relying on zswap.
3. Debug zswap efficiency issues at the cgroup level without needing to
correlate global stats with individual cgroups.
While the compression ratio can be estimated from existing stats (zswap /
zswapped * PAGE_SIZE), this doesn't distinguish between "uniformly poor
compression" and "a few completely incompressible pages mixed with highly
compressible ones". The zswap_incomp stat provides direct visibility into
the latter case.
Link: https://lkml.kernel.org/r/20260213071827.5688-1-jiayuan.chen@linux.dev
Link: https://lkml.kernel.org/r/20260213071827.5688-2-jiayuan.chen@linux.dev
Link: https://lore.kernel.org/linux-mm/CAF8kJuONDFj4NAksaR4j_WyDbNwNGYLmTe-o76rqU17La=nkOw@mail.gmail.com/ [1]
Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com>
Acked-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Michal Koutný <mkoutny@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
We currently have two different sets of helpers for getting or putting the
private IDs' refcount for order 0 and large folios. This is redundant.
Just use one and always acquire the refcount of the swapout folio size
unless it's zero, and put the refcount using the folio size if the charge
failed, since the folio size can't change. Then there is no need to
update the refcount for tail pages.
Same for freeing, then only one pair of get/put helper is needed now.
The performance might be slightly better, too: both "inc unless zero" and
"add unless zero" use the same cmpxchg implementation. For large folios,
we saved an atomic operation. And for both order 0 and large folios, we
saved a branch.
Link: https://lkml.kernel.org/r/20260213-memcg-privid-v1-1-d8cb7afcf831@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Chen Ridong <chenridong@huaweicloud.com>
Acked-by: Shakeel Butt <shakeel.butt@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
File seals are used on memfd for making shared memory communication with
untrusted peers safer and simpler. Seals provide a guarantee that certain
operations won't be allowed on the file such as writes or truncations.
Maintaining these guarantees across a live update will help keeping such
use cases secure.
These guarantees will also be needed for IOMMUFD preservation with LUO.
Normally when IOMMUFD maps a memfd, it pins all its pages to make sure any
truncation operations on the memfd don't lead to IOMMUFD using freed
memory. This doesn't work with LUO since the preserved memfd might have
completely different pages after a live update, and mapping them back to
the IOMMUFD will cause all sorts of problems. Using and preserving the
seals allows IOMMUFD preservation logic to trust the memfd.
Since the uABI defines seals as an int, preserve them by introducing a new
u32 field. There are currently only 6 possible seals, so the extra bits
are unused and provide room for future expansion. Since the seals are
uABI, it is safe to use them directly in the ABI. While at it, also add a
u32 flags field. It makes sure the struct is nicely aligned, and can be
used later to support things like MFD_CLOEXEC.
Since the serialization structure is changed, bump the version number to
"memfd-v2".
It is important to note that the memfd-v2 version only supports seals that
existed when this version was defined. This set is defined by
MEMFD_LUO_ALL_SEALS. Any new seal might bring a completely different
semantic with it and the parser for memfd-v2 cannot be expected to deal
with that. If there are any future seals added, they will need another
version bump.
Link: https://lkml.kernel.org/r/20260216185946.1215770-3-pratyush@kernel.org
Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Tested-by: Samiullah Khawaja <skhawaja@google.com>
Cc: Alexander Graf <graf@amazon.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Clean up and simplify how we check if a folio is swapped. The helper
already requires the folio to be in swap cache and locked. That's enough
to pin the swap cluster from being freed, so there is no need to lock
anything else to avoid UAF.
And besides, we have cleaned up and defined the swap operation to be
mostly folio based, and now the only place a folio will have any of its
swap slots' count increased from 0 to 1 is folio_dup_swap, which also
requires the folio lock. So as we are holding the folio lock here, a
folio can't change its swap status from not swapped (all swap slots have a
count of 0) to swapped (any slot has a swap count larger than 0).
So there won't be any false negatives of this helper if we simply depend
on the folio lock to stabilize the cluster.
We are only using this helper to determine if we can and should release
the swap cache. So false positives are completely harmless, and also
already exist before. Depending on the timing, previously, it's also
possible that a racing thread releases the swap count right after
releasing the ci lock and before this helper returns. In any case, the
worst that could happen is we leave a clean swap cache. It will still be
reclaimed when under pressure just fine.
So, in conclusion, we can simplify and make the check much simpler and
lockless. Also, rename it to folio_maybe_swapped to reflect the design.
Link: https://lkml.kernel.org/r/20260218-swap-table-p3-v3-11-f4e34be021a7@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <ryncsn@gmail.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Now all the infrastructures are ready, switch to using the swap table
only. This is unfortunately a large patch because the whole old counting
mechanism, especially SWP_CONTINUED, has to be gone and switch to the new
mechanism together, with no intermediate steps available.
The swap table is capable of holding up to SWP_TB_COUNT_MAX - 1 counts in
the higher bits of each table entry, so using that, the swap_map can be
completely dropped.
swap_map also had a limit of SWAP_CONT_MAX. Any value beyond that limit
will require a COUNT_CONTINUED page. COUNT_CONTINUED is a bit complex to
maintain, so for the swap table, a simpler approach is used: when the
count goes beyond SWP_TB_COUNT_MAX - 1, the cluster will have an
extend_table allocated, which is a swap cluster-sized array of unsigned
int. The counting is basically offloaded there until the count drops
below SWP_TB_COUNT_MAX again.
Both the swap table and the extend table are cluster-based, so they
exhibit good performance and sparsity.
To make the switch from swap_map to swap table clean, this commit cleans
up and introduces a new set of functions based on the swap table design,
for manipulating swap counts:
- __swap_cluster_dup_entry, __swap_cluster_put_entry,
__swap_cluster_alloc_entry, __swap_cluster_free_entry:
Increase/decrease the count of a swap slot, or alloc / free a swap
slot. This is the internal routine that does the counting work based
on the swap table and handles all the complexities. The caller will
need to lock the cluster before calling them.
All swap count-related update operations are wrapped by these four
helpers.
- swap_dup_entries_cluster, swap_put_entries_cluster:
Increase/decrease the swap count of one or a set of swap slots in the
same cluster range. These two helpers serve as the common routines for
folio_dup_swap & swap_dup_entry_direct, or
folio_put_swap & swap_put_entries_direct.
And use these helpers to replace all existing callers. This helps to
simplify the count tracking by a lot, and the swap_map is gone.
[ryncsn@gmail.com: fix build]
Link: https://lkml.kernel.org/r/aZWuLZi-vYi3vAWe@KASONG-MC4
Link: https://lkml.kernel.org/r/20260218-swap-table-p3-v3-9-f4e34be021a7@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Suggested-by: Chris Li <chrisl@kernel.org>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <ryncsn@gmail.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Swap table entry will need 4 bits reserved for swap count in the shadow,
so the anon shadow should have its leading 4 bits remain 0.
This should be OK for the foreseeable future. Take 52 bits of physical
address space as an example: for 4K pages, there would be at most 40 bits
for addressable pages. Currently, we have 36 bits available (64 - 1 - 16
- 10 - 1, where XA_VALUE takes 1 bit for marker, MEM_CGROUP_ID_SHIFT takes
16 bits, NODES_SHIFT takes <=10 bits, WORKINGSET flags takes 1 bit).
So in the worst case, we previously need to pack the 40 bits of address in
36 bits fields using a 64K bucket (bucket_order = 4). After this, the
bucket will be increased to 1M. Which should be fine, as on such large
machines, the working set size will be way larger than the bucket size.
And for MGLRU's gen number tracking, it should be even more than enough,
MGLRU's gen number (max_seq) increment is much slower compared to the
eviction counter (nonresident_age).
And after all, either the refault distance or the gen distance is only a
hint that can tolerate inaccuracy just fine.
And the 4 bits can be shrunk to 3, or extended to a higher value if needed
later.
Link: https://lkml.kernel.org/r/20260218-swap-table-p3-v3-5-f4e34be021a7@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <ryncsn@gmail.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Slightly clean up the swapon process. Add comments about what swap_lock
protects, introduce and rename helpers that wrap swap_map and cluster_info
setup, and do it outside of the swap_lock lock.
This lock protection is not needed for swap_map and cluster_info setup
because all swap users must either hold the percpu ref or hold a stable
allocated swap entry (e.g., locking a folio in the swap cache) before
accessing. So before the swap device is exposed by enable_swap_info,
nothing would use the swap device's map or cluster.
So we are safe to allocate and set up swap data freely first, then expose
the swap device and set the SWP_WRITEOK flag.
Link: https://lkml.kernel.org/r/20260218-swap-table-p3-v3-2-f4e34be021a7@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <ryncsn@gmail.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Patch series "mm, swap: swap table phase III: remove swap_map", v3.
This series removes the static swap_map and uses the swap table for the
swap count directly. This saves about ~30% memory usage for the static
swap metadata. For example, this saves 256MB of memory when mounting a
1TB swap device. Performance is slightly better too, since the double
update of the swap table and swap_map is now gone.
Test results:
Mounting a swap device:
=======================
Mount a 1TB brd device as SWAP, just to verify the memory save:
`free -m` before:
total used free shared buff/cache available
Mem: 1465 1051 417 1 61 413
Swap: 1054435 0 1054435
`free -m` after:
total used free shared buff/cache available
Mem: 1465 795 672 1 62 670
Swap: 1054435 0 1054435
Idle memory usage is reduced by ~256MB just as expected. And following
this design we should be able to save another ~512MB in a next phase.
Build kernel test:
==================
Test using ZSWAP with NVME SWAP, make -j48, defconfig, in a x86_64 VM
with 5G RAM, under global pressure, avg of 32 test run:
Before After:
System time: 1038.97s 1013.75s (-2.4%)
Test using ZRAM as SWAP, make -j12, tinyconfig, in a ARM64 VM with 1.5G
RAM, under global pressure, avg of 32 test run:
Before After:
System time: 67.75s 66.65s (-1.6%)
The result is slightly better.
Redis / Valkey benchmark:
=========================
Test using ZRAM as SWAP, in a ARM64 VM with 1.5G RAM, under global pressure,
avg of 64 test run:
Server: valkey-server --maxmemory 2560M
Client: redis-benchmark -r 3000000 -n 3000000 -d 1024 -c 12 -P 32 -t get
no persistence with BGSAVE
Before: 472705.71 RPS 369451.68 RPS
After: 481197.93 RPS (+1.8%) 374922.32 RPS (+1.5%)
In conclusion, performance is better in all cases, and memory usage is
much lower.
The swap cgroup array will also be merged into the swap table in a later
phase, saving the other ~60% part of the static swap metadata and making
all the swap metadata dynamic. The improved API for swap operations also
reduces the lock contention and makes more batching operations possible.
This patch (of 12):
/proc/swaps uses si->swap_map as the indicator to check if the swap
device is mounted. swap_map will be removed soon, so change it to use
si->swap_file instead because:
- si->swap_file is exactly the only dynamic content that /proc/swaps is
interested in. Previously, it was checking si->swap_map just to ensure
si->swap_file is available. si->swap_map is set under mutex
protection, and after si->swap_file is set, so having si->swap_map set
guarantees si->swap_file is set.
- Checking si->flags doesn't work here. SWP_WRITEOK is cleared during
swapoff, but /proc/swaps is supposed to show the device under swapoff
too to report the swapoff progress. And SWP_USED is set even if the
device hasn't been properly set up.
We can have another flag, but the easier way is to just check
si->swap_file directly. So protect si->swap_file setting with mutext,
and set si->swap_file only when the swap device is truly enabled.
/proc/swaps only interested in si->swap_file and a few static data
reading. Only si->swap_file needs protection. Reading other static
fields is always fine.
Link: https://lkml.kernel.org/r/20260218-swap-table-p3-v3-0-f4e34be021a7@tencent.com
Link: https://lkml.kernel.org/r/20260218-swap-table-p3-v3-1-f4e34be021a7@tencent.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Acked-by: Chris Li <chrisl@kernel.org>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Kairui Song <ryncsn@gmail.com>
Cc: kernel test robot <lkp@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
There are situations where reclaim kicks in on a system with free memory.
One possible cause is a NUMA imbalance scenario where one or more nodes
are under pressure. It would help if we could easily identify such nodes.
Move the pgscan, pgsteal, and pgrefill counters from vm_event_item to
node_stat_item to provide per-node reclaim visibility. With these
counters as node stats, the values are now displayed in the per-node
section of /proc/zoneinfo, which allows for quick identification of the
affected nodes.
/proc/vmstat continues to report the same counters, aggregated across all
nodes. But the ordering of these items within the readout changes as they
move from the vm events section to the node stats section.
Memcg accounting of these counters is preserved. The relocated counters
remain visible in memory.stat alongside the existing aggregate pgscan and
pgsteal counters.
However, this change affects how the global counters are accumulated.
Previously, the global event count update was gated on !cgroup_reclaim(),
excluding memcg-based reclaim from /proc/vmstat. Now that
mod_lruvec_state() is being used to update the counters, the global
counters will include all reclaim. This is consistent with how pgdemote
counters are already tracked.
Finally, the virtio_balloon driver is updated to use
global_node_page_state() to fetch the counters, as they are no longer
accessible through the vm_events array.
Link: https://lkml.kernel.org/r/20260219235846.161910-1-jp.kobryn@linux.dev
Signed-off-by: JP Kobryn <jp.kobryn@linux.dev>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Eugenio Pérez <eperezma@redhat.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jason Wang <jasowang@redhat.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: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stop using the maple big node for rebalance operations by changing to more
align with spanning store. The rebalance operation needs its own data
calculation in rebalance_data().
In the event of too much data, the rebalance tries to push the data using
push_data_sib(). If there is insufficient data, the rebalance operation
will rebalance against a sibling (found with rebalance_sib()).
The rebalance starts at the leaf and works its way upward in the tree
using rebalance_ascend(). Most of the code is shared with spanning store
such as the copy node having a new root, but is fundamentally different in
that the data must come from a sibling.
A parent maple state is used to track the parent location to avoid
multiple mas_ascend() calls. The maple state tree location is copied from
the parent to the mas (child) in the ascend step. Ascending itself is
done in the main loop.
Link: https://lkml.kernel.org/r/20260130205935.2559335-23-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andrew Ballance <andrewjballance@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christian Kujau <lists@nerdbynature.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stop using the maple subtree state and big node in favour of using three
destinations in the maple copy node. That is, expand the way leaves were
handled to all levels of the tree and use the maple copy node to track the
new nodes.
Extract out the sibling init into the data calculation since this is where
the insufficient data can be detected. The remainder of the sibling code
to shift the next iteration is moved to the spanning_ascend() function,
since it is not always needed.
Next introduce the dst_setup() function which will decide how many nodes
are needed to contain the data at this level. Using the destination
count, populate the copy node's dst array with the new nodes and set
d_count to the correct value. Note that this can be tricky in the case of
a leaf node with exactly enough room because of the rule against NULLs at
the end of leaves.
Once the destinations are ready, copy the data by altering the
cp_data_write() function to copy from the sources to the destinations
directly. This eliminates the use of the big node in this code path. On
node completion, node_finalise() will zero out the remaining area and set
the metadata, if necessary.
spanning_ascend() is used to decide if the operation is complete. It may
create a new root, converge into one destination, or continue upwards by
ascending the left and right write maple states.
One test case setup needed to be tweaked so that the targeted node was
surrounded by full nodes.
[akpm@linux-foundation.org: coding-style cleanups]
Link: https://lkml.kernel.org/r/20260130205935.2559335-18-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andrew Ballance <andrewjballance@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christian Kujau <lists@nerdbynature.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Introduce an internal-memory only node type called maple_copy to
facilitate internal copy operations. Use it in mas_spanning_rebalance()
for just the leaf nodes. Initially, the maple_copy node is used to
configure the source nodes and copy the data into the big_node.
The maple_copy contains a list of source entries with start and end
offsets. One of the maple_copy entries can be itself with an offset of 0
to 2, representing the data where the store partially overwrites entries,
or fully overwrites the entry. The side effect is that the source nodes
no longer have to worry about partially copying the existing offset if it
is not fully overwritten.
This is in preparation of removal of the maple big_node, but for the time
being the data is copied to the big node to limit the change size.
Link: https://lkml.kernel.org/r/20260130205935.2559335-12-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Andrew Ballance <andrewjballance@gmail.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Christian Kujau <lists@nerdbynature.de>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: SeongJae Park <sj@kernel.org>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
