From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CF1EA21C16D for ; Wed, 14 May 2025 22:03:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747260186; cv=none; b=WqGy2HFDiuWFDtyeiBUp1SprsmYNNzFOvqg9tsLbhRQ2mqk8oJWq+0BXVa9cWil4BGjl7n+CsWroMBgWy1UMQik5sP3Xmdl90ArpVGIkMJ5atqaBSdZRflRw6/vV0qVcvQsIuDcJCHTdsnh6x5+71gMUy8a7Yz7KoXbZrPPzrvU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747260186; c=relaxed/simple; bh=iju6OhhXcXraDhUFj2MHB6OY0uTlkLEPwcqguCgn2Lw=; h=Date:To:From:Subject:Message-Id; b=MCSFqbi1iC/2q/kWuRgobn7/L3fwnPjLukyXaVI8lSVNF90Es+640iBhI8WwJeUjULSF8PhKvQJ6NCJvdZIY2lu5Avl0eNpjCe2ReuLfPr7/pYt/1TCrhbs4IibXyVAfuno0QDN6Az/VbfGmelLbbAt9qmKgiDupRA4+gkyAmQE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=fDvga+Bq; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="fDvga+Bq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 478F8C4CEE3; Wed, 14 May 2025 22:03:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1747260186; bh=iju6OhhXcXraDhUFj2MHB6OY0uTlkLEPwcqguCgn2Lw=; h=Date:To:From:Subject:From; b=fDvga+BqQpwpqbwbfy0ssERhZ2M0q3sAnif7XHfYMPFhsMmu0yF4S0OMWJCH5G6lx XMwd+QiH0yHiV8hQPQ7MAiW3qlyXyOUgfgr5C8zq+ICvFviIoAeZG+Sb9tnH7sWDAQ GbjXls3J71Vh3m2N8HaQIySJHR44k9EGJbp3/QQg= Date: Wed, 14 May 2025 15:03:05 -0700 To: mm-commits@vger.kernel.org,vbabka@suse.cz,roman.gushchin@linux.dev,muchun.song@linux.dev,mhocko@kernel.org,hannes@cmpxchg.org,bigeasy@linutronix.de,ast@kernel.org,shakeel.butt@linux.dev,akpm@linux-foundation.org From: Andrew Morton Subject: + memcg-move-preempt-disable-to-callers-of-memcg_rstat_updated.patch added to mm-new branch Message-Id: <20250514220306.478F8C4CEE3@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: memcg: move preempt disable to callers of memcg_rstat_updated has been added to the -mm mm-new branch. Its filename is memcg-move-preempt-disable-to-callers-of-memcg_rstat_updated.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/memcg-move-preempt-disable-to-callers-of-memcg_rstat_updated.patch This patch will later appear in the mm-new branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Note, mm-new is a provisional staging ground for work-in-progress patches, and acceptance into mm-new is a notification for others take notice and to finish up reviews. Please do not hesitate to respond to review feedback and post updated versions to replace or incrementally fixup patches in mm-new. Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Shakeel Butt Subject: memcg: move preempt disable to callers of memcg_rstat_updated Date: Wed, 14 May 2025 11:41:53 -0700 Let's move the explicit preempt disable code to the callers of memcg_rstat_updated and also remove the memcg_stats_lock and related functions which ensures the callers of stats update functions have disabled preemption because now the stats update functions are explicitly disabling preemption. Link: https://lkml.kernel.org/r/20250514184158.3471331-3-shakeel.butt@linux.dev Signed-off-by: Shakeel Butt Acked-by: Vlastimil Babka Cc: Alexei Starovoitov Cc: Johannes Weiner Cc: Michal Hocko Cc: Muchun Song Cc: Roman Gushchin Cc: Sebastian Andrzej Siewior Signed-off-by: Andrew Morton --- mm/memcontrol.c | 74 +++++++++++----------------------------------- 1 file changed, 19 insertions(+), 55 deletions(-) --- a/mm/memcontrol.c~memcg-move-preempt-disable-to-callers-of-memcg_rstat_updated +++ a/mm/memcontrol.c @@ -557,48 +557,22 @@ static u64 flush_last_time; #define FLUSH_TIME (2UL*HZ) -/* - * Accessors to ensure that preemption is disabled on PREEMPT_RT because it can - * not rely on this as part of an acquired spinlock_t lock. These functions are - * never used in hardirq context on PREEMPT_RT and therefore disabling preemtion - * is sufficient. - */ -static void memcg_stats_lock(void) -{ - preempt_disable_nested(); - VM_WARN_ON_IRQS_ENABLED(); -} - -static void __memcg_stats_lock(void) -{ - preempt_disable_nested(); -} - -static void memcg_stats_unlock(void) -{ - preempt_enable_nested(); -} - - static bool memcg_vmstats_needs_flush(struct memcg_vmstats *vmstats) { return atomic64_read(&vmstats->stats_updates) > MEMCG_CHARGE_BATCH * num_online_cpus(); } -static inline void memcg_rstat_updated(struct mem_cgroup *memcg, int val) +static inline void memcg_rstat_updated(struct mem_cgroup *memcg, int val, + int cpu) { struct memcg_vmstats_percpu __percpu *statc_pcpu; struct memcg_vmstats_percpu *statc; - int cpu; unsigned int stats_updates; if (!val) return; - /* Don't assume callers have preemption disabled. */ - cpu = get_cpu(); - cgroup_rstat_updated(memcg->css.cgroup, cpu); statc_pcpu = memcg->vmstats_percpu; for (; statc_pcpu; statc_pcpu = statc->parent_pcpu) { @@ -619,7 +593,6 @@ static inline void memcg_rstat_updated(s stats_updates = this_cpu_xchg(statc_pcpu->stats_updates, 0); atomic64_add(stats_updates, &statc->vmstats->stats_updates); } - put_cpu(); } static void __mem_cgroup_flush_stats(struct mem_cgroup *memcg, bool force) @@ -717,6 +690,7 @@ void __mod_memcg_state(struct mem_cgroup int val) { int i = memcg_stats_index(idx); + int cpu; if (mem_cgroup_disabled()) return; @@ -724,12 +698,14 @@ void __mod_memcg_state(struct mem_cgroup if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) return; - memcg_stats_lock(); + cpu = get_cpu(); + __this_cpu_add(memcg->vmstats_percpu->state[i], val); val = memcg_state_val_in_pages(idx, val); - memcg_rstat_updated(memcg, val); + memcg_rstat_updated(memcg, val, cpu); trace_mod_memcg_state(memcg, idx, val); - memcg_stats_unlock(); + + put_cpu(); } #ifdef CONFIG_MEMCG_V1 @@ -758,6 +734,7 @@ static void __mod_memcg_lruvec_state(str struct mem_cgroup_per_node *pn; struct mem_cgroup *memcg; int i = memcg_stats_index(idx); + int cpu; if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) return; @@ -765,24 +742,7 @@ static void __mod_memcg_lruvec_state(str pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec); memcg = pn->memcg; - /* - * The caller from rmap relies on disabled preemption because they never - * update their counter from in-interrupt context. For these two - * counters we check that the update is never performed from an - * interrupt context while other caller need to have disabled interrupt. - */ - __memcg_stats_lock(); - if (IS_ENABLED(CONFIG_DEBUG_VM)) { - switch (idx) { - case NR_ANON_MAPPED: - case NR_FILE_MAPPED: - case NR_ANON_THPS: - WARN_ON_ONCE(!in_task()); - break; - default: - VM_WARN_ON_IRQS_ENABLED(); - } - } + cpu = get_cpu(); /* Update memcg */ __this_cpu_add(memcg->vmstats_percpu->state[i], val); @@ -791,9 +751,10 @@ static void __mod_memcg_lruvec_state(str __this_cpu_add(pn->lruvec_stats_percpu->state[i], val); val = memcg_state_val_in_pages(idx, val); - memcg_rstat_updated(memcg, val); + memcg_rstat_updated(memcg, val, cpu); trace_mod_memcg_lruvec_state(memcg, idx, val); - memcg_stats_unlock(); + + put_cpu(); } /** @@ -873,6 +834,7 @@ void __count_memcg_events(struct mem_cgr unsigned long count) { int i = memcg_events_index(idx); + int cpu; if (mem_cgroup_disabled()) return; @@ -880,11 +842,13 @@ void __count_memcg_events(struct mem_cgr if (WARN_ONCE(BAD_STAT_IDX(i), "%s: missing stat item %d\n", __func__, idx)) return; - memcg_stats_lock(); + cpu = get_cpu(); + __this_cpu_add(memcg->vmstats_percpu->events[i], count); - memcg_rstat_updated(memcg, count); + memcg_rstat_updated(memcg, count, cpu); trace_count_memcg_events(memcg, idx, count); - memcg_stats_unlock(); + + put_cpu(); } unsigned long memcg_events(struct mem_cgroup *memcg, int event) _ Patches currently in -mm which might be from shakeel.butt@linux.dev are memcg-memcg_rstat_updated-re-entrant-safe-against-irqs.patch memcg-move-preempt-disable-to-callers-of-memcg_rstat_updated.patch memcg-make-mod_memcg_state-re-entrant-safe-against-irqs.patch memcg-make-count_memcg_events-re-entrant-safe-against-irqs.patch memcg-make-__mod_memcg_lruvec_state-re-entrant-safe-against-irqs.patch memcg-no-stock-lock-for-cpu-hot-unplug.patch memcg-objcg-stock-trylock-without-irq-disabling.patch