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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 02/35] mm, slub: allocate private object map for debugfs listings
Date: Thu, 29 Jul 2021 15:20:59 +0200	[thread overview]
Message-ID: <20210729132132.19691-3-vbabka@suse.cz> (raw)
In-Reply-To: <20210729132132.19691-1-vbabka@suse.cz>

Slub has a static spinlock protected bitmap for marking which objects are on
freelist when it wants to list them, for situations where dynamically
allocating such map can lead to recursion or locking issues, and on-stack
bitmap would be too large.

The handlers of debugfs files alloc_traces and free_traces also currently use this
shared bitmap, but their syscall context makes it straightforward to allocate a
private map before entering locked sections, so switch these processing paths
to use a private bitmap.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Christoph Lameter <cl@linux.com>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
---
 mm/slub.c | 44 +++++++++++++++++++++++++++++---------------
 1 file changed, 29 insertions(+), 15 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 422a61d7bf5f..66795aec6e10 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -454,6 +454,18 @@ static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
 static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)];
 static DEFINE_SPINLOCK(object_map_lock);
 
+static void __fill_map(unsigned long *obj_map, struct kmem_cache *s,
+		       struct page *page)
+{
+	void *addr = page_address(page);
+	void *p;
+
+	bitmap_zero(obj_map, page->objects);
+
+	for (p = page->freelist; p; p = get_freepointer(s, p))
+		set_bit(__obj_to_index(s, addr, p), obj_map);
+}
+
 #if IS_ENABLED(CONFIG_KUNIT)
 static bool slab_add_kunit_errors(void)
 {
@@ -483,17 +495,11 @@ static inline bool slab_add_kunit_errors(void) { return false; }
 static unsigned long *get_map(struct kmem_cache *s, struct page *page)
 	__acquires(&object_map_lock)
 {
-	void *p;
-	void *addr = page_address(page);
-
 	VM_BUG_ON(!irqs_disabled());
 
 	spin_lock(&object_map_lock);
 
-	bitmap_zero(object_map, page->objects);
-
-	for (p = page->freelist; p; p = get_freepointer(s, p))
-		set_bit(__obj_to_index(s, addr, p), object_map);
+	__fill_map(object_map, s, page);
 
 	return object_map;
 }
@@ -4874,17 +4880,17 @@ static int add_location(struct loc_track *t, struct kmem_cache *s,
 }
 
 static void process_slab(struct loc_track *t, struct kmem_cache *s,
-		struct page *page, enum track_item alloc)
+		struct page *page, enum track_item alloc,
+		unsigned long *obj_map)
 {
 	void *addr = page_address(page);
 	void *p;
-	unsigned long *map;
 
-	map = get_map(s, page);
+	__fill_map(obj_map, s, page);
+
 	for_each_object(p, s, addr, page->objects)
-		if (!test_bit(__obj_to_index(s, addr, p), map))
+		if (!test_bit(__obj_to_index(s, addr, p), obj_map))
 			add_location(t, s, get_track(s, p, alloc));
-	put_map(map);
 }
 #endif  /* CONFIG_DEBUG_FS   */
 #endif	/* CONFIG_SLUB_DEBUG */
@@ -5811,14 +5817,21 @@ static int slab_debug_trace_open(struct inode *inode, struct file *filep)
 	struct loc_track *t = __seq_open_private(filep, &slab_debugfs_sops,
 						sizeof(struct loc_track));
 	struct kmem_cache *s = file_inode(filep)->i_private;
+	unsigned long *obj_map;
+
+	obj_map = bitmap_alloc(oo_objects(s->oo), GFP_KERNEL);
+	if (!obj_map)
+		return -ENOMEM;
 
 	if (strcmp(filep->f_path.dentry->d_name.name, "alloc_traces") == 0)
 		alloc = TRACK_ALLOC;
 	else
 		alloc = TRACK_FREE;
 
-	if (!alloc_loc_track(t, PAGE_SIZE / sizeof(struct location), GFP_KERNEL))
+	if (!alloc_loc_track(t, PAGE_SIZE / sizeof(struct location), GFP_KERNEL)) {
+		bitmap_free(obj_map);
 		return -ENOMEM;
+	}
 
 	for_each_kmem_cache_node(s, node, n) {
 		unsigned long flags;
@@ -5829,12 +5842,13 @@ static int slab_debug_trace_open(struct inode *inode, struct file *filep)
 
 		spin_lock_irqsave(&n->list_lock, flags);
 		list_for_each_entry(page, &n->partial, slab_list)
-			process_slab(t, s, page, alloc);
+			process_slab(t, s, page, alloc, obj_map);
 		list_for_each_entry(page, &n->full, slab_list)
-			process_slab(t, s, page, alloc);
+			process_slab(t, s, page, alloc, obj_map);
 		spin_unlock_irqrestore(&n->list_lock, flags);
 	}
 
+	bitmap_free(obj_map);
 	return 0;
 }
 
-- 
2.32.0



  parent reply	other threads:[~2021-07-29 13:21 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 ` Vlastimil Babka [this message]
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 ` [PATCH v3 32/35] mm, slub: make slab_lock() disable irqs with PREEMPT_RT Vlastimil Babka
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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