[PATCH v2 3/8] mm/vmstat: Use preempt_[dis|en]able_nested()

[PATCH v2 3/8] mm/vmstat: Use preempt_[dis|en]able_nested()

[Sebastian Andrzej Siewior]

From: Thomas Gleixner <tglx@linutronix.de>

Replace the open coded CONFIG_PREEMPT_RT conditional
preempt_enable/disable() pairs with the new helper functions which hide
the underlying implementation details.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 mm/vmstat.c | 36 ++++++++++++------------------------
 1 file changed, 12 insertions(+), 24 deletions(-)

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 373d2730fcf21..d514fe7f90af0 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -355,8 +355,7 @@ void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 	 * CPU migrations and preemption potentially corrupts a counter so
 	 * disable preemption.
 	 */
-	if (IS_ENABLED(CONFIG_PREEMPT_RT))
-		preempt_disable();
+	preempt_disable_nested();
 
 	x = delta + __this_cpu_read(*p);
 
@@ -368,8 +367,7 @@ void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 	}
 	__this_cpu_write(*p, x);
 
-	if (IS_ENABLED(CONFIG_PREEMPT_RT))
-		preempt_enable();
+	preempt_enable_nested();
 }
 EXPORT_SYMBOL(__mod_zone_page_state);
 
@@ -393,8 +391,7 @@ void __mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
 	}
 
 	/* See __mod_node_page_state */
-	if (IS_ENABLED(CONFIG_PREEMPT_RT))
-		preempt_disable();
+	preempt_disable_nested();
 
 	x = delta + __this_cpu_read(*p);
 
@@ -406,8 +403,7 @@ void __mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
 	}
 	__this_cpu_write(*p, x);
 
-	if (IS_ENABLED(CONFIG_PREEMPT_RT))
-		preempt_enable();
+	preempt_enable_nested();
 }
 EXPORT_SYMBOL(__mod_node_page_state);
 
@@ -441,8 +437,7 @@ void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
 	s8 v, t;
 
 	/* See __mod_node_page_state */
-	if (IS_ENABLED(CONFIG_PREEMPT_RT))
-		preempt_disable();
+	preempt_disable_nested();
 
 	v = __this_cpu_inc_return(*p);
 	t = __this_cpu_read(pcp->stat_threshold);
@@ -453,8 +448,7 @@ void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
 		__this_cpu_write(*p, -overstep);
 	}
 
-	if (IS_ENABLED(CONFIG_PREEMPT_RT))
-		preempt_enable();
+	preempt_enable_nested();
 }
 
 void __inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
@@ -466,8 +460,7 @@ void __inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
 	VM_WARN_ON_ONCE(vmstat_item_in_bytes(item));
 
 	/* See __mod_node_page_state */
-	if (IS_ENABLED(CONFIG_PREEMPT_RT))
-		preempt_disable();
+	preempt_disable_nested();
 
 	v = __this_cpu_inc_return(*p);
 	t = __this_cpu_read(pcp->stat_threshold);
@@ -478,8 +471,7 @@ void __inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
 		__this_cpu_write(*p, -overstep);
 	}
 
-	if (IS_ENABLED(CONFIG_PREEMPT_RT))
-		preempt_enable();
+	preempt_enable_nested();
 }
 
 void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
@@ -501,8 +493,7 @@ void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
 	s8 v, t;
 
 	/* See __mod_node_page_state */
-	if (IS_ENABLED(CONFIG_PREEMPT_RT))
-		preempt_disable();
+	preempt_disable_nested();
 
 	v = __this_cpu_dec_return(*p);
 	t = __this_cpu_read(pcp->stat_threshold);
@@ -513,8 +504,7 @@ void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
 		__this_cpu_write(*p, overstep);
 	}
 
-	if (IS_ENABLED(CONFIG_PREEMPT_RT))
-		preempt_enable();
+	preempt_enable_nested();
 }
 
 void __dec_node_state(struct pglist_data *pgdat, enum node_stat_item item)
@@ -526,8 +516,7 @@ void __dec_node_state(struct pglist_data *pgdat, enum node_stat_item item)
 	VM_WARN_ON_ONCE(vmstat_item_in_bytes(item));
 
 	/* See __mod_node_page_state */
-	if (IS_ENABLED(CONFIG_PREEMPT_RT))
-		preempt_disable();
+	preempt_disable_nested();
 
 	v = __this_cpu_dec_return(*p);
 	t = __this_cpu_read(pcp->stat_threshold);
@@ -538,8 +527,7 @@ void __dec_node_state(struct pglist_data *pgdat, enum node_stat_item item)
 		__this_cpu_write(*p, overstep);
 	}
 
-	if (IS_ENABLED(CONFIG_PREEMPT_RT))
-		preempt_enable();
+	preempt_enable_nested();
 }
 
 void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
-- 
2.37.2

Re: [PATCH v2 3/8] mm/vmstat: Use preempt_[dis|en]able_nested()

[Michal Hocko]

On Thu 25-08-22 18:41:26, Sebastian Andrzej Siewior wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
> 
> Replace the open coded CONFIG_PREEMPT_RT conditional
> preempt_enable/disable() pairs with the new helper functions which hide
> the underlying implementation details.
> 
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: linux-mm@kvack.org
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

Acked-by: Michal Hocko <mhocko@suse.com>
Thanks!

> ---
>  mm/vmstat.c | 36 ++++++++++++------------------------
>  1 file changed, 12 insertions(+), 24 deletions(-)
> 
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 373d2730fcf21..d514fe7f90af0 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -355,8 +355,7 @@ void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
>  	 * CPU migrations and preemption potentially corrupts a counter so
>  	 * disable preemption.
>  	 */
> -	if (IS_ENABLED(CONFIG_PREEMPT_RT))
> -		preempt_disable();
> +	preempt_disable_nested();
>  
>  	x = delta + __this_cpu_read(*p);
>  
> @@ -368,8 +367,7 @@ void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
>  	}
>  	__this_cpu_write(*p, x);
>  
> -	if (IS_ENABLED(CONFIG_PREEMPT_RT))
> -		preempt_enable();
> +	preempt_enable_nested();
>  }
>  EXPORT_SYMBOL(__mod_zone_page_state);
>  
> @@ -393,8 +391,7 @@ void __mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
>  	}
>  
>  	/* See __mod_node_page_state */
> -	if (IS_ENABLED(CONFIG_PREEMPT_RT))
> -		preempt_disable();
> +	preempt_disable_nested();
>  
>  	x = delta + __this_cpu_read(*p);
>  
> @@ -406,8 +403,7 @@ void __mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
>  	}
>  	__this_cpu_write(*p, x);
>  
> -	if (IS_ENABLED(CONFIG_PREEMPT_RT))
> -		preempt_enable();
> +	preempt_enable_nested();
>  }
>  EXPORT_SYMBOL(__mod_node_page_state);
>  
> @@ -441,8 +437,7 @@ void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
>  	s8 v, t;
>  
>  	/* See __mod_node_page_state */
> -	if (IS_ENABLED(CONFIG_PREEMPT_RT))
> -		preempt_disable();
> +	preempt_disable_nested();
>  
>  	v = __this_cpu_inc_return(*p);
>  	t = __this_cpu_read(pcp->stat_threshold);
> @@ -453,8 +448,7 @@ void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
>  		__this_cpu_write(*p, -overstep);
>  	}
>  
> -	if (IS_ENABLED(CONFIG_PREEMPT_RT))
> -		preempt_enable();
> +	preempt_enable_nested();
>  }
>  
>  void __inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
> @@ -466,8 +460,7 @@ void __inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
>  	VM_WARN_ON_ONCE(vmstat_item_in_bytes(item));
>  
>  	/* See __mod_node_page_state */
> -	if (IS_ENABLED(CONFIG_PREEMPT_RT))
> -		preempt_disable();
> +	preempt_disable_nested();
>  
>  	v = __this_cpu_inc_return(*p);
>  	t = __this_cpu_read(pcp->stat_threshold);
> @@ -478,8 +471,7 @@ void __inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
>  		__this_cpu_write(*p, -overstep);
>  	}
>  
> -	if (IS_ENABLED(CONFIG_PREEMPT_RT))
> -		preempt_enable();
> +	preempt_enable_nested();
>  }
>  
>  void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
> @@ -501,8 +493,7 @@ void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
>  	s8 v, t;
>  
>  	/* See __mod_node_page_state */
> -	if (IS_ENABLED(CONFIG_PREEMPT_RT))
> -		preempt_disable();
> +	preempt_disable_nested();
>  
>  	v = __this_cpu_dec_return(*p);
>  	t = __this_cpu_read(pcp->stat_threshold);
> @@ -513,8 +504,7 @@ void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
>  		__this_cpu_write(*p, overstep);
>  	}
>  
> -	if (IS_ENABLED(CONFIG_PREEMPT_RT))
> -		preempt_enable();
> +	preempt_enable_nested();
>  }
>  
>  void __dec_node_state(struct pglist_data *pgdat, enum node_stat_item item)
> @@ -526,8 +516,7 @@ void __dec_node_state(struct pglist_data *pgdat, enum node_stat_item item)
>  	VM_WARN_ON_ONCE(vmstat_item_in_bytes(item));
>  
>  	/* See __mod_node_page_state */
> -	if (IS_ENABLED(CONFIG_PREEMPT_RT))
> -		preempt_disable();
> +	preempt_disable_nested();
>  
>  	v = __this_cpu_dec_return(*p);
>  	t = __this_cpu_read(pcp->stat_threshold);
> @@ -538,8 +527,7 @@ void __dec_node_state(struct pglist_data *pgdat, enum node_stat_item item)
>  		__this_cpu_write(*p, overstep);
>  	}
>  
> -	if (IS_ENABLED(CONFIG_PREEMPT_RT))
> -		preempt_enable();
> +	preempt_enable_nested();
>  }
>  
>  void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
> -- 
> 2.37.2

-- 
Michal Hocko
SUSE Labs

[PATCH v2 4/8] mm/debug: Provide VM_WARN_ON_IRQS_ENABLED()

[Sebastian Andrzej Siewior]

From: Thomas Gleixner <tglx@linutronix.de>

Some places in the VM code expect interrupts disabled, which is a valid
expectation on non-PREEMPT_RT kernels, but does not hold on RT kernels in
some places because the RT spinlock substitution does not disable
interrupts.

To avoid sprinkling CONFIG_PREEMPT_RT conditionals into those places,
provide VM_WARN_ON_IRQS_ENABLED() which is only enabled when VM_DEBUG=y and
PREEMPT_RT=n.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 include/linux/mmdebug.h | 6 ++++++
 lib/Kconfig.debug       | 3 +++
 2 files changed, 9 insertions(+)

diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h
index 15ae78cd28536..b8728d11c9490 100644
--- a/include/linux/mmdebug.h
+++ b/include/linux/mmdebug.h
@@ -94,6 +94,12 @@ void dump_mm(const struct mm_struct *mm);
 #define VM_WARN(cond, format...) BUILD_BUG_ON_INVALID(cond)
 #endif
 
+#ifdef CONFIG_DEBUG_VM_IRQSOFF
+#define VM_WARN_ON_IRQS_ENABLED() WARN_ON_ONCE(!irqs_disabled())
+#else
+#define VM_WARN_ON_IRQS_ENABLED() do { } while (0)
+#endif
+
 #ifdef CONFIG_DEBUG_VIRTUAL
 #define VIRTUAL_BUG_ON(cond) BUG_ON(cond)
 #else
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 072e4b289c13e..c96fc6820544c 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -803,6 +803,9 @@ config ARCH_HAS_DEBUG_VM_PGTABLE
 	  An architecture should select this when it can successfully
 	  build and run DEBUG_VM_PGTABLE.
 
+config DEBUG_VM_IRQSOFF
+	def_bool DEBUG_VM && !PREEMPT_RT
+
 config DEBUG_VM
 	bool "Debug VM"
 	depends on DEBUG_KERNEL
-- 
2.37.2

Re: [PATCH v2 4/8] mm/debug: Provide VM_WARN_ON_IRQS_ENABLED()

[Michal Hocko]

On Thu 25-08-22 18:41:27, Sebastian Andrzej Siewior wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
> 
> Some places in the VM code expect interrupts disabled, which is a valid
> expectation on non-PREEMPT_RT kernels, but does not hold on RT kernels in
> some places because the RT spinlock substitution does not disable
> interrupts.
> 
> To avoid sprinkling CONFIG_PREEMPT_RT conditionals into those places,
> provide VM_WARN_ON_IRQS_ENABLED() which is only enabled when VM_DEBUG=y and
> PREEMPT_RT=n.
> 
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: linux-mm@kvack.org
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

Acked-by: Michal Hocko <mhocko@suse.com>
Thanks!

> ---
>  include/linux/mmdebug.h | 6 ++++++
>  lib/Kconfig.debug       | 3 +++
>  2 files changed, 9 insertions(+)
> 
> diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h
> index 15ae78cd28536..b8728d11c9490 100644
> --- a/include/linux/mmdebug.h
> +++ b/include/linux/mmdebug.h
> @@ -94,6 +94,12 @@ void dump_mm(const struct mm_struct *mm);
>  #define VM_WARN(cond, format...) BUILD_BUG_ON_INVALID(cond)
>  #endif
>  
> +#ifdef CONFIG_DEBUG_VM_IRQSOFF
> +#define VM_WARN_ON_IRQS_ENABLED() WARN_ON_ONCE(!irqs_disabled())
> +#else
> +#define VM_WARN_ON_IRQS_ENABLED() do { } while (0)
> +#endif
> +
>  #ifdef CONFIG_DEBUG_VIRTUAL
>  #define VIRTUAL_BUG_ON(cond) BUG_ON(cond)
>  #else
> diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
> index 072e4b289c13e..c96fc6820544c 100644
> --- a/lib/Kconfig.debug
> +++ b/lib/Kconfig.debug
> @@ -803,6 +803,9 @@ config ARCH_HAS_DEBUG_VM_PGTABLE
>  	  An architecture should select this when it can successfully
>  	  build and run DEBUG_VM_PGTABLE.
>  
> +config DEBUG_VM_IRQSOFF
> +	def_bool DEBUG_VM && !PREEMPT_RT
> +
>  config DEBUG_VM
>  	bool "Debug VM"
>  	depends on DEBUG_KERNEL
> -- 
> 2.37.2

-- 
Michal Hocko
SUSE Labs

[PATCH v2 5/8] mm/memcontrol: Replace the PREEMPT_RT conditionals

[Sebastian Andrzej Siewior]

From: Thomas Gleixner <tglx@linutronix.de>

Use VM_WARN_ON_IRQS_ENABLED() and preempt_disable/enable_nested() to
replace the CONFIG_PREEMPT_RT #ifdeffery.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: cgroups@vger.kernel.org
Cc: linux-mm@kvack.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 mm/memcontrol.c | 19 ++++++-------------
 1 file changed, 6 insertions(+), 13 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b69979c9ced5c..d35b6fa560f0a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -597,25 +597,18 @@ static u64 flush_next_time;
  */
 static void memcg_stats_lock(void)
 {
-#ifdef CONFIG_PREEMPT_RT
-      preempt_disable();
-#else
-      VM_BUG_ON(!irqs_disabled());
-#endif
+	preempt_disable_nested();
+	VM_WARN_ON_IRQS_ENABLED();
 }
 
 static void __memcg_stats_lock(void)
 {
-#ifdef CONFIG_PREEMPT_RT
-      preempt_disable();
-#endif
+	preempt_disable_nested();
 }
 
 static void memcg_stats_unlock(void)
 {
-#ifdef CONFIG_PREEMPT_RT
-      preempt_enable();
-#endif
+	preempt_enable_nested();
 }
 
 static inline void memcg_rstat_updated(struct mem_cgroup *memcg, int val)
@@ -715,7 +708,7 @@ void __mod_memcg_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
 	 * interrupt context while other caller need to have disabled interrupt.
 	 */
 	__memcg_stats_lock();
-	if (IS_ENABLED(CONFIG_DEBUG_VM) && !IS_ENABLED(CONFIG_PREEMPT_RT)) {
+	if (IS_ENABLED(CONFIG_DEBUG_VM)) {
 		switch (idx) {
 		case NR_ANON_MAPPED:
 		case NR_FILE_MAPPED:
@@ -725,7 +718,7 @@ void __mod_memcg_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
 			WARN_ON_ONCE(!in_task());
 			break;
 		default:
-			WARN_ON_ONCE(!irqs_disabled());
+			VM_WARN_ON_IRQS_ENABLED();
 		}
 	}
 
-- 
2.37.2

Re: [PATCH v2 5/8] mm/memcontrol: Replace the PREEMPT_RT conditionals

[Michal Hocko]

On Thu 25-08-22 18:41:28, Sebastian Andrzej Siewior wrote:
> From: Thomas Gleixner <tglx@linutronix.de>
> 
> Use VM_WARN_ON_IRQS_ENABLED() and preempt_disable/enable_nested() to
> replace the CONFIG_PREEMPT_RT #ifdeffery.
> 
> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Michal Hocko <mhocko@kernel.org>
> Cc: Roman Gushchin <roman.gushchin@linux.dev>
> Cc: Shakeel Butt <shakeelb@google.com>
> Cc: Muchun Song <songmuchun@bytedance.com>
> Cc: cgroups@vger.kernel.org
> Cc: linux-mm@kvack.org
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
> Reviewed-by: Muchun Song <songmuchun@bytedance.com>
> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

Acked-by: Michal Hocko <mhocko@suse.com>
Thanks!

> ---
>  mm/memcontrol.c | 19 ++++++-------------
>  1 file changed, 6 insertions(+), 13 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index b69979c9ced5c..d35b6fa560f0a 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -597,25 +597,18 @@ static u64 flush_next_time;
>   */
>  static void memcg_stats_lock(void)
>  {
> -#ifdef CONFIG_PREEMPT_RT
> -      preempt_disable();
> -#else
> -      VM_BUG_ON(!irqs_disabled());
> -#endif
> +	preempt_disable_nested();
> +	VM_WARN_ON_IRQS_ENABLED();
>  }
>  
>  static void __memcg_stats_lock(void)
>  {
> -#ifdef CONFIG_PREEMPT_RT
> -      preempt_disable();
> -#endif
> +	preempt_disable_nested();
>  }
>  
>  static void memcg_stats_unlock(void)
>  {
> -#ifdef CONFIG_PREEMPT_RT
> -      preempt_enable();
> -#endif
> +	preempt_enable_nested();
>  }
>  
>  static inline void memcg_rstat_updated(struct mem_cgroup *memcg, int val)
> @@ -715,7 +708,7 @@ void __mod_memcg_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
>  	 * interrupt context while other caller need to have disabled interrupt.
>  	 */
>  	__memcg_stats_lock();
> -	if (IS_ENABLED(CONFIG_DEBUG_VM) && !IS_ENABLED(CONFIG_PREEMPT_RT)) {
> +	if (IS_ENABLED(CONFIG_DEBUG_VM)) {
>  		switch (idx) {
>  		case NR_ANON_MAPPED:
>  		case NR_FILE_MAPPED:
> @@ -725,7 +718,7 @@ void __mod_memcg_lruvec_state(struct lruvec *lruvec, enum node_stat_item idx,
>  			WARN_ON_ONCE(!in_task());
>  			break;
>  		default:
> -			WARN_ON_ONCE(!irqs_disabled());
> +			VM_WARN_ON_IRQS_ENABLED();
>  		}
>  	}
>  
> -- 
> 2.37.2

-- 
Michal Hocko
SUSE Labs

[PATCH v2 6/8] mm/compaction: Get rid of RT ifdeffery

[Sebastian Andrzej Siewior]

From: Thomas Gleixner <tglx@linutronix.de>

Move the RT dependency for the initial value of
sysctl_compact_unevictable_allowed into Kconfig.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Terrell <terrelln@fb.com>
Cc: linux-mm@kvack.org
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 mm/Kconfig      | 6 ++++++
 mm/compaction.c | 6 +-----
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/mm/Kconfig b/mm/Kconfig
index 0331f1461f81c..3897e924e40f2 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -579,6 +579,12 @@ config COMPACTION
 	  it and then we would be really interested to hear about that at
 	  linux-mm@kvack.org.
 
+config COMPACT_UNEVICTABLE_DEFAULT
+	int
+	depends on COMPACTION
+	default 0 if PREEMPT_RT
+	default 1
+
 #
 # support for free page reporting
 config PAGE_REPORTING
diff --git a/mm/compaction.c b/mm/compaction.c
index 640fa76228dd9..10561cb1aaad9 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1727,11 +1727,7 @@ typedef enum {
  * Allow userspace to control policy on scanning the unevictable LRU for
  * compactable pages.
  */
-#ifdef CONFIG_PREEMPT_RT
-int sysctl_compact_unevictable_allowed __read_mostly = 0;
-#else
-int sysctl_compact_unevictable_allowed __read_mostly = 1;
-#endif
+int sysctl_compact_unevictable_allowed __read_mostly = CONFIG_COMPACT_UNEVICTABLE_DEFAULT;
 
 static inline void
 update_fast_start_pfn(struct compact_control *cc, unsigned long pfn)
-- 
2.37.2