The patch titled
Subject: mm/vmstat: refresh stats remotely instead of via work item
has been added to the -mm mm-unstable branch. Its filename is
mm-vmstat-refresh-stats-remotely-instead-of-via-work-item.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vmstat-refresh-stats-remotely-instead-of-via-work-item.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Subject: mm/vmstat: refresh stats remotely instead of via work item
Date: Fri, 03 Mar 2023 16:58:52 -0300
Refresh per-CPU stats remotely, instead of queueing work items, for the
stat_refresh procfs method.
This fixes sosreport hang (which uses vmstat_refresh) with spinning
SCHED_FIFO process.
Link: https://lkml.kernel.org/r/20230303195909.029065935@xxxxxxxxxx
Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Cc: Aaron Tomlin <atomlin@xxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Frederic Weisbecker <frederic@xxxxxxxxxx>
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: "H. Peter Anvin" <hpa@xxxxxxxxx>
Cc: Huacai Chen <chenhuacai@xxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: "Russell King (Oracle)" <linux@xxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
--- a/mm/vmstat.c~mm-vmstat-refresh-stats-remotely-instead-of-via-work-item
+++ a/mm/vmstat.c
@@ -1866,11 +1866,21 @@ static DEFINE_PER_CPU(struct delayed_wor
int sysctl_stat_interval __read_mostly = HZ;
#ifdef CONFIG_PROC_FS
+
+#ifdef CONFIG_HAVE_CMPXCHG_LOCAL
+static int refresh_all_vm_stats(void);
+#else
static void refresh_vm_stats(struct work_struct *work)
{
refresh_cpu_vm_stats();
}
+static int refresh_all_vm_stats(void)
+{
+ return schedule_on_each_cpu(refresh_vm_stats);
+}
+#endif
+
int vmstat_refresh(struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
@@ -1892,7 +1902,7 @@ int vmstat_refresh(struct ctl_table *tab
* transiently negative values, report an error here if any of
* the stats is negative, so we know to go looking for imbalance.
*/
- err = schedule_on_each_cpu(refresh_vm_stats);
+ err = refresh_all_vm_stats();
if (err)
return err;
for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
@@ -2012,7 +2022,7 @@ static DECLARE_DEFERRABLE_WORK(shepherd,
#ifdef CONFIG_HAVE_CMPXCHG_LOCAL
/* Flush counters remotely if CPU uses cmpxchg to update its per-CPU counters */
-static void vmstat_shepherd(struct work_struct *w)
+static int refresh_all_vm_stats(void)
{
int cpu;
@@ -2022,7 +2032,12 @@ static void vmstat_shepherd(struct work_
cond_resched();
}
cpus_read_unlock();
+ return 0;
+}
+static void vmstat_shepherd(struct work_struct *w)
+{
+ refresh_all_vm_stats();
schedule_delayed_work(&shepherd,
round_jiffies_relative(sysctl_stat_interval));
}
_
Patches currently in -mm which might be from mtosatti@xxxxxxxxxx are
mm-vmstat-remove-remote-node-draining.patch
this_cpu_cmpxchg-arm64-switch-this_cpu_cmpxchg-to-locked-add-_local-function.patch
this_cpu_cmpxchg-loongarch-switch-this_cpu_cmpxchg-to-locked-add-_local-function.patch
this_cpu_cmpxchg-s390-switch-this_cpu_cmpxchg-to-locked-add-_local-function.patch
this_cpu_cmpxchg-x86-switch-this_cpu_cmpxchg-to-locked-add-_local-function.patch
add-this_cpu_cmpxchg_local-and-asm-generic-definitions.patch
convert-this_cpu_cmpxchg-users-to-this_cpu_cmpxchg_local.patch
mm-vmstat-switch-counter-modification-to-cmpxchg.patch
mm-vmstat-use-xchg-in-cpu_vm_stats_fold.patch
mm-vmstat-switch-vmstat-shepherd-to-flush-per-cpu-counters-remotely.patch
mm-vmstat-refresh-stats-remotely-instead-of-via-work-item.patch
