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meminfo: add a per node counter for balloon drivers

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Patch series "track memory used by balloon drivers", v2.

This series introduces a way to track memory used by balloon drivers.

Add a NR_BALLOON_PAGES counter to track how many pages are reclaimed by
the balloon drivers.  First add the accounting, then updates the balloon
drivers (virtio, Hyper-V, VMware, Pseries-cmm, and Xen) to maintain this
counter.  The virtio, Vmware, and pseries-cmm balloon drivers utilize the
balloon_compaction interface to allocate and free balloon pages.  Other
balloon drivers will have to maintain this counter manually.

This makes the information visible in memory reporting interfaces like
/proc/meminfo, show_mem, and OOM reporting.

This provides admins visibility into their VM balloon sizes without
requiring different virtualization tooling.  Furthermore, this information
is helpful when debugging an OOM inside a VM.


This patch (of 4):

Add NR_BALLOON_PAGES counter to track memory used by balloon drivers and
expose it through /proc/meminfo and other memory reporting interfaces.

[npache@redhat.com: document Balloon Meminfo entry]
  Link: https://lkml.kernel.org/r/a0315ccf-f244-460e-8643-fd7388724fe5@redhat.com
Link: https://lkml.kernel.org/r/20250314213757.244258-1-npache@redhat.com
Link: https://lkml.kernel.org/r/20250314213757.244258-2-npache@redhat.com
Signed-off-by: Nico Pache <npache@redhat.com>
Cc: Alexander Atanasov <alexander.atanasov@virtuozzo.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dexuan Cui <decui@microsoft.com>
Cc: Haiyang Zhang <haiyangz@microsoft.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Juegren Gross <jgross@suse.com>
Cc: Kanchana P Sridhar <kanchana.p.sridhar@intel.com>
Cc: K. Y. Srinivasan <kys@microsoft.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Wei Liu <wei.liu@kernel.org>
Cc: Michael Kelley <mhklinux@outlook.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Nico Pache
2025-03-14 15:37:54 -06:00
committed by Andrew Morton
parent 0d2a260523
commit 835de37603
5 changed files with 10 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
Documentation/filesystems/proc.rst
View File

@@ -1081,6 +1081,7 @@ Example output. You may not have all of these fields.
FilePmdMapped: 0 kB
CmaTotal: 0 kB
CmaFree: 0 kB
Balloon: 0 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
@@ -1255,6 +1256,8 @@ CmaTotal
Memory reserved for the Contiguous Memory Allocator (CMA)
CmaFree
Free remaining memory in the CMA reserves
Balloon
Memory returned to Host by VM Balloon Drivers
HugePages_Total, HugePages_Free, HugePages_Rsvd, HugePages_Surp, Hugepagesize, Hugetlb
See Documentation/admin-guide/mm/hugetlbpage.rst.
DirectMap4k, DirectMap2M, DirectMap1G

2
fs/proc/meminfo.c
View File

@@ -162,6 +162,8 @@ static int meminfo_proc_show(struct seq_file *m, void *v)
show_val_kb(m, "Unaccepted: ",
global_zone_page_state(NR_UNACCEPTED));
#endif
show_val_kb(m, "Balloon: ",
global_node_page_state(NR_BALLOON_PAGES));
hugetlb_report_meminfo(m);

1
include/linux/mmzone.h
View File

@@ -224,6 +224,7 @@ enum node_stat_item {
#ifdef CONFIG_HUGETLB_PAGE
NR_HUGETLB,
#endif
NR_BALLOON_PAGES,
NR_VM_NODE_STAT_ITEMS
};

4
mm/show_mem.c
View File

@@ -260,6 +260,7 @@ static void show_free_areas(unsigned int filter, nodemask_t *nodemask, int max_z
" pagetables:%lukB"
" sec_pagetables:%lukB"
" all_unreclaimable? %s"
" Balloon:%lukB"
"\n",
pgdat->node_id,
K(node_page_state(pgdat, NR_ACTIVE_ANON)),
@@ -285,7 +286,8 @@ static void show_free_areas(unsigned int filter, nodemask_t *nodemask, int max_z
#endif
K(node_page_state(pgdat, NR_PAGETABLE)),
K(node_page_state(pgdat, NR_SECONDARY_PAGETABLE)),
str_yes_no(pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES));
str_yes_no(pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES),
K(node_page_state(pgdat, NR_BALLOON_PAGES)));
}
for_each_populated_zone(zone) {

1
mm/vmstat.c
View File

@@ -1277,6 +1277,7 @@ const char * const vmstat_text[] = {
#ifdef CONFIG_HUGETLB_PAGE
"nr_hugetlb",
#endif
"nr_balloon_pages",
/* system-wide enum vm_stat_item counters */
"nr_dirty_threshold",
"nr_dirty_background_threshold",