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From: Vlastimil Babka <vbabka@suse.cz>
To: Andrew Morton <akpm@linux-foundation.org>,
	Christoph Lameter <cl@linux.com>,
	David Rientjes <rientjes@google.com>,
	Pekka Enberg <penberg@kernel.org>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	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 v5 02/35] mm, slub: allocate private object map for debugfs listings
Date: Mon, 23 Aug 2021 16:57:53 +0200	[thread overview]
Message-ID: <20210823145826.3857-3-vbabka@suse.cz> (raw)
In-Reply-To: <20210823145826.3857-1-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 f6063ec97a55..fb603fdf58cb 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;
 }
@@ -4879,17 +4885,17 @@ 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 */
@@ -5816,14 +5822,21 @@ 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;
@@ -5834,12 +5847,13 @@ 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:[~2021-08-23 14:59 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-23 14:57 [PATCH v5 00/35] SLUB: reduce irq disabled scope and make it RT compatible Vlastimil Babka
2021-08-23 14:57 ` [PATCH v5 01/35] mm, slub: don't call flush_all() from slab_debug_trace_open() Vlastimil Babka
2021-08-23 14:57 ` Vlastimil Babka [this message]
2021-08-23 14:57 ` [PATCH v5 03/35] mm, slub: allocate private object map for validate_slab_cache() Vlastimil Babka
2021-08-23 14:57 ` [PATCH v5 04/35] mm, slub: don't disable irq for debug_check_no_locks_freed() Vlastimil Babka
2021-08-23 14:57 ` [PATCH v5 05/35] mm, slub: remove redundant unfreeze_partials() from put_cpu_partial() Vlastimil Babka
2021-08-23 14:57 ` [PATCH v5 06/35] mm, slub: unify cmpxchg_double_slab() and __cmpxchg_double_slab() Vlastimil Babka
2021-08-23 14:57 ` [PATCH v5 07/35] mm, slub: extract get_partial() from new_slab_objects() Vlastimil Babka
2021-08-23 14:57 ` [PATCH v5 08/35] mm, slub: dissolve new_slab_objects() into ___slab_alloc() Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 09/35] mm, slub: return slab page from get_partial() and set c->page afterwards Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 10/35] mm, slub: restructure new page checks in ___slab_alloc() Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 11/35] mm, slub: simplify kmem_cache_cpu and tid setup Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 12/35] mm, slub: move disabling/enabling irqs to ___slab_alloc() Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 13/35] mm, slub: do initial checks in ___slab_alloc() with irqs enabled Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 14/35] mm, slub: move disabling irqs closer to get_partial() in ___slab_alloc() Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 15/35] mm, slub: restore irqs around calling new_slab() Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 16/35] mm, slub: validate slab from partial list or page allocator before making it cpu slab Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 17/35] mm, slub: check new pages with restored irqs Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 18/35] mm, slub: stop disabling irqs around get_partial() Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 19/35] mm, slub: move reset of c->page and freelist out of deactivate_slab() Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 20/35] mm, slub: make locking in deactivate_slab() irq-safe Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 21/35] mm, slub: call deactivate_slab() without disabling irqs Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 22/35] mm, slub: move irq control into unfreeze_partials() Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 23/35] mm, slub: discard slabs in unfreeze_partials() without irqs disabled Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 24/35] mm, slub: detach whole partial list at once in unfreeze_partials() Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 25/35] mm, slub: separate detaching of partial list in unfreeze_partials() from unfreezing Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 26/35] mm, slub: only disable irq with spin_lock in __unfreeze_partials() Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 27/35] mm, slub: don't disable irqs in slub_cpu_dead() Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 28/35] mm, slab: make flush_slab() possible to call with irqs enabled Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 29/35] mm: slub: Move flush_cpu_slab() invocations __free_slab() invocations out of IRQ context Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 30/35] mm: slub: Make object_map_lock a raw_spinlock_t Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 31/35] mm, slub: optionally save/restore irqs in slab_[un]lock()/ Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 32/35] mm, slub: make slab_lock() disable irqs with PREEMPT_RT Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 33/35] mm, slub: protect put_cpu_partial() with disabled irqs instead of cmpxchg Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 34/35] mm, slub: use migrate_disable() on PREEMPT_RT Vlastimil Babka
2021-08-23 14:58 ` [PATCH v5 35/35] mm, slub: convert kmem_cpu_slab protection to local_lock Vlastimil Babka
2021-08-23 15:11 ` [PATCH v5 00/35] SLUB: reduce irq disabled scope and make it RT compatible Sebastian Andrzej Siewior

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