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mm/vmstat: make MEMCG select VM_EVENT_COUNTERS 

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>
pull/1311/head
Kirill A. Shutemov 2025-06-04 12:51:11 +03:00 committed by Andrew Morton
parent 7ae7e811f0
commit fdc5001b00
3 changed files with 5 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/linux/vmstat.h
View File

@ -507,7 +507,7 @@ static inline const char *lru_list_name(enum lru_list lru)
return node_stat_name(NR_LRU_BASE + lru) + 3; // skip "nr_"
}
#if defined(CONFIG_VM_EVENT_COUNTERS) || defined(CONFIG_MEMCG)
#if defined(CONFIG_VM_EVENT_COUNTERS)
static inline const char *vm_event_name(enum vm_event_item item)
{
return vmstat_text[NR_VM_ZONE_STAT_ITEMS +
@ -516,7 +516,7 @@ static inline const char *vm_event_name(enum vm_event_item item)
NR_VM_STAT_ITEMS +
item];
}
#endif /* CONFIG_VM_EVENT_COUNTERS || CONFIG_MEMCG */
#endif /* CONFIG_VM_EVENT_COUNTERS */
#ifdef CONFIG_MEMCG

1
init/Kconfig
View File

@ -992,6 +992,7 @@ config MEMCG
select PAGE_COUNTER
select EVENTFD
select SLAB_OBJ_EXT
select VM_EVENT_COUNTERS
help
Provides control over the memory footprint of tasks in a cgroup.

4
mm/vmstat.c
View File

@ -1287,7 +1287,7 @@ const char * const vmstat_text[] = {
"nr_memmap_pages",
"nr_memmap_boot_pages",
#if defined(CONFIG_VM_EVENT_COUNTERS) || defined(CONFIG_MEMCG)
#if defined(CONFIG_VM_EVENT_COUNTERS)
/* enum vm_event_item counters */
"pgpgin",
"pgpgout",
@ -1475,7 +1475,7 @@ const char * const vmstat_text[] = {
"kstack_rest",
#endif
#endif
#endif /* CONFIG_VM_EVENT_COUNTERS || CONFIG_MEMCG */
#endif /* CONFIG_VM_EVENT_COUNTERS */
};
#endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA || CONFIG_MEMCG */