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Wed, 1 Feb 2023 16:51:49 -0300 (-03) Message-ID: <20230201195104.507817318@redhat.com> User-Agent: quilt/0.67 Date: Wed, 01 Feb 2023 16:50:18 -0300 From: Marcelo Tosatti To: Christoph Lameter Cc: Aaron Tomlin , Frederic Weisbecker , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Marcelo Tosatti Subject: [PATCH 5/5] mm/vmstat: refresh stats remotely instead of via work item References: <20230201195013.881721887@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.3 X-Stat-Signature: jae4q8sgrif6fcx45q4g1dgtiygkau3m X-Rspam-User: X-Rspamd-Queue-Id: 7338112001C X-Rspamd-Server: rspam06 X-HE-Tag: 1675281158-513768 X-HE-Meta: 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 PnjNM9GU nWlvPVpL/TsbcgrsjQqqXRyF6FEwijPHyWOKC0+NlAH0TxDdUbiA50B6efrZjtZ3aZ9t3uwTD2ivm4iF4EHj6rLma+VfJITiKHCZVW8RzcBLTW+YyWYWbcTBg3Bna7QhXVWsAfmm2NxpG3WOq/g9Jq73jdUYD9kIwv+OZDaEUq7ZLZa3SqDvs3m9KQvojeOwqafW33QFIcaVbU58= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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. Signed-off-by: Marcelo Tosatti Index: linux-vmstat-remote/mm/vmstat.c =================================================================== --- linux-vmstat-remote.orig/mm/vmstat.c +++ linux-vmstat-remote/mm/vmstat.c @@ -1865,11 +1865,21 @@ 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) { @@ -1889,7 +1899,7 @@ 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++) { @@ -2009,7 +2019,7 @@ 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; @@ -2019,7 +2029,12 @@ 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)); }