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Thu, 9 Feb 2023 12:32:51 -0300 (-03) Message-ID: <20230209153204.929333982@redhat.com> User-Agent: quilt/0.67 Date: Thu, 09 Feb 2023 12:02:01 -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 v2 11/11] mm/vmstat: refresh stats remotely instead of via work item References: <20230209150150.380060673@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.9 X-Rspam-User: X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: DB934A002C X-Stat-Signature: eskmyqynzsk3xu63mdec6wpmmy3zgo6i X-HE-Tag: 1675956801-165118 X-HE-Meta: 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 duuvmvdz sCvITxQnP6+bwWdEe4w53g3k+52aZYtKOL7amoVlaDnIEDpnNcSF9n4shYmv2ke1NcxRLiVzn8UmnHGsyFa50Pa6AVxMxoCft4MAzBEXMZj4/anAoP4LKKEU++3tRPRy33ttLPF8vX3eT5L2ocDiegC3d72kKJPohv5ReJy3Buiao2PVRC0QtDFx44RrpIJwAGdn4S9I1W24OGCo= 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-2.6/mm/vmstat.c =================================================================== --- linux-2.6.orig/mm/vmstat.c +++ linux-2.6/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)); }