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From: Vlastimil Babka <vbabka@suse.cz>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	Christoph Lameter <cl@linux.com>,
	David Rientjes <rientjes@google.com>,
	Pekka Enberg <penberg@kernel.org>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mike Galbraith <efault@gmx.de>,
	Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Mel Gorman <mgorman@techsingularity.net>,
	Jesper Dangaard Brouer <brouer@redhat.com>,
	Jann Horn <jannh@google.com>, Vlastimil Babka <vbabka@suse.cz>
Subject: [PATCH v3 32/35] mm, slub: make slab_lock() disable irqs with PREEMPT_RT
Date: Thu, 29 Jul 2021 15:21:29 +0200	[thread overview]
Message-ID: <20210729132132.19691-33-vbabka@suse.cz> (raw)
In-Reply-To: <20210729132132.19691-1-vbabka@suse.cz>

We need to disable irqs around slab_lock() (a bit spinlock) to make it
irq-safe. The calls to slab_lock() are nested under spin_lock_irqsave() which
doesn't disable irqs on PREEMPT_RT, so add explicit disabling with PREEMPT_RT.

We also distinguish cmpxchg_double_slab() where we do the disabling explicitly
and __cmpxchg_double_slab() for contexts with already disabled irqs.  However
these context are also typically spin_lock_irqsave() thus insufficient on
PREEMPT_RT. Thus, change __cmpxchg_double_slab() to be same as
cmpxchg_double_slab() on PREEMPT_RT.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
 mm/slub.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 2496e0add6f2..4f7218797603 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -380,12 +380,12 @@ __slab_unlock(struct page *page, unsigned long *flags, bool disable_irqs)
 static __always_inline void
 slab_lock(struct page *page, unsigned long *flags)
 {
-	__slab_lock(page, flags, false);
+	__slab_lock(page, flags, IS_ENABLED(CONFIG_PREEMPT_RT));
 }
 
 static __always_inline void slab_unlock(struct page *page, unsigned long *flags)
 {
-	__slab_unlock(page, flags, false);
+	__slab_unlock(page, flags, IS_ENABLED(CONFIG_PREEMPT_RT));
 }
 
 static inline bool ___cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
@@ -428,14 +428,19 @@ static inline bool ___cmpxchg_double_slab(struct kmem_cache *s, struct page *pag
 	return false;
 }
 
-/* Interrupts must be disabled (for the fallback code to work right) */
+/*
+ * Interrupts must be disabled (for the fallback code to work right), typically
+ * by an _irqsave() lock variant. Except on PREEMPT_RT where locks are different
+ * so we disable interrupts explicitly here.
+ */
 static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
 		void *freelist_old, unsigned long counters_old,
 		void *freelist_new, unsigned long counters_new,
 		const char *n)
 {
 	return ___cmpxchg_double_slab(s, page, freelist_old, counters_old,
-				      freelist_new, counters_new, n, false);
+				      freelist_new, counters_new, n,
+				      IS_ENABLED(CONFIG_PREEMPT_RT));
 }
 
 static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
-- 
2.32.0



  parent reply	other threads:[~2021-07-29 13:22 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-29 13:20 [PATCH v3 00/35] SLUB: reduce irq disabled scope and make it RT compatible Vlastimil Babka
2021-07-29 13:20 ` [PATCH v3 01/35] mm, slub: don't call flush_all() from slab_debug_trace_open() Vlastimil Babka
2021-07-29 13:20 ` [PATCH v3 02/35] mm, slub: allocate private object map for debugfs listings Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 03/35] mm, slub: allocate private object map for validate_slab_cache() Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 04/35] mm, slub: don't disable irq for debug_check_no_locks_freed() Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 05/35] mm, slub: remove redundant unfreeze_partials() from put_cpu_partial() Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 06/35] mm, slub: unify cmpxchg_double_slab() and __cmpxchg_double_slab() Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 07/35] mm, slub: extract get_partial() from new_slab_objects() Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 08/35] mm, slub: dissolve new_slab_objects() into ___slab_alloc() Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 09/35] mm, slub: return slab page from get_partial() and set c->page afterwards Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 10/35] mm, slub: restructure new page checks in ___slab_alloc() Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 11/35] mm, slub: simplify kmem_cache_cpu and tid setup Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 12/35] mm, slub: move disabling/enabling irqs to ___slab_alloc() Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 13/35] mm, slub: do initial checks in ___slab_alloc() with irqs enabled Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 14/35] mm, slub: move disabling irqs closer to get_partial() in ___slab_alloc() Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 15/35] mm, slub: restore irqs around calling new_slab() Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 16/35] mm, slub: validate slab from partial list or page allocator before making it cpu slab Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 17/35] mm, slub: check new pages with restored irqs Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 18/35] mm, slub: stop disabling irqs around get_partial() Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 19/35] mm, slub: move reset of c->page and freelist out of deactivate_slab() Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 20/35] mm, slub: make locking in deactivate_slab() irq-safe Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 21/35] mm, slub: call deactivate_slab() without disabling irqs Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 22/35] mm, slub: move irq control into unfreeze_partials() Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 23/35] mm, slub: discard slabs in unfreeze_partials() without irqs disabled Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 24/35] mm, slub: detach whole partial list at once in unfreeze_partials() Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 25/35] mm, slub: separate detaching of partial list in unfreeze_partials() from unfreezing Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 26/35] mm, slub: only disable irq with spin_lock in __unfreeze_partials() Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 27/35] mm, slub: don't disable irqs in slub_cpu_dead() Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 28/35] mm, slab: make flush_slab() possible to call with irqs enabled Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 29/35] mm: slub: Move flush_cpu_slab() invocations __free_slab() invocations out of IRQ context Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 30/35] mm: slub: Make object_map_lock a raw_spinlock_t Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 31/35] mm, slub: optionally save/restore irqs in slab_[un]lock()/ Vlastimil Babka
2021-07-29 15:43   ` Mel Gorman
2021-07-29 13:21 ` Vlastimil Babka [this message]
2021-07-29 13:21 ` [PATCH v3 33/35] mm, slub: protect put_cpu_partial() with disabled irqs instead of cmpxchg Vlastimil Babka
2021-07-29 15:42   ` Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 34/35] mm, slub: use migrate_disable() on PREEMPT_RT Vlastimil Babka
2021-07-29 13:21 ` [PATCH v3 35/35] mm, slub: convert kmem_cpu_slab protection to local_lock Vlastimil Babka
2021-07-29 15:24 ` [PATCH v3 00/35] SLUB: reduce irq disabled scope and make it RT compatible Sebastian Andrzej Siewior
2021-07-29 15:27   ` Vlastimil Babka
2021-07-29 15:29     ` Sebastian Andrzej Siewior
2021-07-29 15:30       ` Sebastian Andrzej Siewior
2021-07-29 15:31       ` Vlastimil Babka
2021-07-29 15:47 ` Vlastimil Babka
2021-07-30  9:19   ` Sebastian Andrzej Siewior
2021-08-04 12:05 ` Mel Gorman
2021-08-04 12:14   ` Vlastimil Babka

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