include/linux/vmstat.h | 1 + mm/show_mem.c | 10 ++++++++++ mm/vmstat.c | 15 ++++++++++----- 3 files changed, 21 insertions(+), 5 deletions(-)
The memory stat is not done in real time, it have some gap with
real value. In CPU-less NUMA node, the values of MemTotal and
MemFree can be nearly equal, the gap may cause MemFree bigger
than MemTotal, it leads MemUsed is negative which print as a large
positive number.
cat /sys/devices/system/node/node17/meminfo
Node 17 MemTotal: 4194304 kB
Node 17 MemFree: 4195552 kB
Node 17 MemUsed: 18446744073709550368 kB
Node 17 Active: 52 kB
Node 17 Inactive: 320 kB
Node 17 Active(anon): 0 kB
Node 17 Inactive(anon): 0 kB
Node 17 Active(file): 52 kB
Node 17 Inactive(file): 320 kB
Node 17 Unevictable: 0 kB
Node 17 Mlocked: 0 kB
Node 17 Dirty: 0 kB
Node 17 Writeback: 0 kB
Node 17 FilePages: 372 kB
Node 17 Mapped: 320 kB
Node 17 AnonPages: 0 kB
Node 17 Shmem: 0 kB
Node 17 KernelStack: 0 kB
Node 17 PageTables: 0 kB
Node 17 NFS_Unstable: 0 kB
Node 17 Bounce: 0 kB
Node 17 WritebackTmp: 0 kB
Node 17 KReclaimable: 0 kB
Node 17 Slab: 0 kB
Node 17 SReclaimable: 0 kB
Node 17 SUnreclaim: 0 kB
Node 17 AnonHugePages: 79872 kB
Node 17 ShmemHugePages: 0 kB
Node 17 ShmemPmdMapped: 0 kB
Node 17 FileHugePages: 0 kB
Node 17 FilePmdMapped: 0 kB
Node 17 HugePages_Total: 0
Node 17 HugePages_Free: 0
Node 17 HugePages_Surp: 0
To avoid this exception by refreshing vm_stat, when MemFree
is bigger than MemTotal.
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
---
include/linux/vmstat.h | 1 +
mm/show_mem.c | 10 ++++++++++
mm/vmstat.c | 15 ++++++++++-----
3 files changed, 21 insertions(+), 5 deletions(-)
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 3c9c266cf782..6a7d2f3757b0 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -259,6 +259,7 @@ extern unsigned long node_page_state(struct pglist_data *pgdat,
enum node_stat_item item);
extern unsigned long node_page_state_pages(struct pglist_data *pgdat,
enum node_stat_item item);
+extern int refresh_node_page_state(void);
extern void fold_vm_numa_events(void);
#else
#define sum_zone_node_page_state(node, item) global_zone_page_state(item)
diff --git a/mm/show_mem.c b/mm/show_mem.c
index 43aca5a2ac99..dc8d2b6056d3 100644
--- a/mm/show_mem.c
+++ b/mm/show_mem.c
@@ -106,6 +106,16 @@ void si_meminfo_node(struct sysinfo *val, int nid)
val->totalram = managed_pages;
val->sharedram = node_page_state(pgdat, NR_SHMEM);
val->freeram = sum_zone_node_page_state(nid, NR_FREE_PAGES);
+ if (val->freeram > val->totalram) {
+ int err = refresh_node_page_state();
+ if (err)
+ val->freeram = val->totalram;
+ else
+ val->freeram = sum_zone_node_page_state(nid, NR_FREE_PAGES);
+
+ if (val->freeram > val->totalram)
+ val->freeram = val->totalram;
+ }
val->totalhigh = managed_highpages;
val->freehigh = free_highpages;
val->mem_unit = PAGE_SIZE;
diff --git a/mm/vmstat.c b/mm/vmstat.c
index f534972f517d..96a2e03ec83e 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -881,6 +881,11 @@ static bool refresh_cpu_vm_stats(bool do_pagesets)
return changed;
}
+static void refresh_vm_stats(struct work_struct *work)
+{
+ refresh_cpu_vm_stats(true);
+}
+
/*
* Fold the data for an offline cpu into the global array.
* There cannot be any access by the offline cpu and therefore
@@ -1024,6 +1029,11 @@ unsigned long node_page_state(struct pglist_data *pgdat,
return node_page_state_pages(pgdat, item);
}
+
+int refresh_node_page_state(void)
+{
+ return schedule_on_each_cpu(refresh_vm_stats);
+}
#endif
/*
@@ -1970,11 +1980,6 @@ static int sysctl_stat_interval __read_mostly = HZ;
static int vmstat_late_init_done;
#ifdef CONFIG_PROC_FS
-static void refresh_vm_stats(struct work_struct *work)
-{
- refresh_cpu_vm_stats(true);
-}
-
static int vmstat_refresh(const struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
--
2.25.1On 4/13/26 13:57, Yang Yingliang wrote: > The memory stat is not done in real time, it have some gap with > real value. In CPU-less NUMA node, the values of MemTotal and > MemFree can be nearly equal, the gap may cause MemFree bigger > than MemTotal, it leads MemUsed is negative which print as a large > positive number. How does this interact with CPU-less NUMA node? Some concurrent memory hotunplug, or how could be possible get MemFree that is larger than MemTotal? > > cat /sys/devices/system/node/node17/meminfo > Node 17 MemTotal: 4194304 kB > Node 17 MemFree: 4195552 kB > Node 17 MemUsed: 18446744073709550368 kB > Node 17 Active: 52 kB > Node 17 Inactive: 320 kB > Node 17 Active(anon): 0 kB > Node 17 Inactive(anon): 0 kB > Node 17 Active(file): 52 kB > Node 17 Inactive(file): 320 kB > Node 17 Unevictable: 0 kB > Node 17 Mlocked: 0 kB > Node 17 Dirty: 0 kB > Node 17 Writeback: 0 kB > Node 17 FilePages: 372 kB > Node 17 Mapped: 320 kB > Node 17 AnonPages: 0 kB > Node 17 Shmem: 0 kB > Node 17 KernelStack: 0 kB > Node 17 PageTables: 0 kB > Node 17 NFS_Unstable: 0 kB > Node 17 Bounce: 0 kB > Node 17 WritebackTmp: 0 kB > Node 17 KReclaimable: 0 kB > Node 17 Slab: 0 kB > Node 17 SReclaimable: 0 kB > Node 17 SUnreclaim: 0 kB > Node 17 AnonHugePages: 79872 kB > Node 17 ShmemHugePages: 0 kB > Node 17 ShmemPmdMapped: 0 kB > Node 17 FileHugePages: 0 kB > Node 17 FilePmdMapped: 0 kB > Node 17 HugePages_Total: 0 > Node 17 HugePages_Free: 0 > Node 17 HugePages_Surp: 0 > > To avoid this exception by refreshing vm_stat, when MemFree > is bigger than MemTotal. > -- Cheers, David
Hi Yang,
kernel test robot noticed the following build warnings:
[auto build test WARNING on akpm-mm/mm-everything]
url: https://github.com/intel-lab-lkp/linux/commits/Yang-Yingliang/mm-make-sure-freeram-is-smaller-than-totalram/20260415-122059
base: https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link: https://lore.kernel.org/r/20260413115736.1237680-1-yangyingliang%40huawei.com
patch subject: [PATCH -next] mm: make sure freeram is smaller than totalram
config: arm64-randconfig-001-20260415 (https://download.01.org/0day-ci/archive/20260415/202604151917.t6ckjppJ-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 15.2.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260415/202604151917.t6ckjppJ-lkp@intel.com/reproduce)
If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202604151917.t6ckjppJ-lkp@intel.com/
All warnings (new ones prefixed by >>):
>> mm/vmstat.c:884:13: warning: 'refresh_vm_stats' defined but not used [-Wunused-function]
884 | static void refresh_vm_stats(struct work_struct *work)
| ^~~~~~~~~~~~~~~~
vim +/refresh_vm_stats +884 mm/vmstat.c
883
> 884 static void refresh_vm_stats(struct work_struct *work)
885 {
886 refresh_cpu_vm_stats(true);
887 }
888
--
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