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Wed, 09 Jun 2021 11:39:31 +0000 From: Vlastimil Babka To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Christoph Lameter , David Rientjes , Pekka Enberg , Joonsoo Kim Cc: Sebastian Andrzej Siewior , Thomas Gleixner , Mel Gorman , Jesper Dangaard Brouer , Peter Zijlstra , Jann Horn , Vlastimil Babka Subject: [RFC v2 02/34] mm, slub: allocate private object map for sysfs listings Date: Wed, 9 Jun 2021 13:38:31 +0200 Message-Id: <20210609113903.1421-3-vbabka@suse.cz> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210609113903.1421-1-vbabka@suse.cz> References: <20210609113903.1421-1-vbabka@suse.cz> MIME-Version: 1.0 Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=S79B+ZPY; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=tvWi3K3s; dkim=pass header.d=suse.cz header.s=susede2_rsa header.b=S79B+ZPY; dkim=pass header.d=suse.cz header.s=susede2_ed25519 header.b=tvWi3K3s; dmarc=none; spf=pass (imf04.hostedemail.com: domain of vbabka@suse.cz designates 195.135.220.29 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Rspamd-Server: rspam02 X-Stat-Signature: bs3tgr35qka6mftd1sak6y4obddxwxt6 X-Rspamd-Queue-Id: 778033C3 X-HE-Tag: 1623238770-51391 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 sysfs files alloc_calls and free_calls also currently use= this shared bitmap, but their syscall context makes it straightforward to allo= cate a private map before entering locked sections, so switch these processing p= aths to use a private bitmap. Signed-off-by: Vlastimil Babka Acked-by: Christoph Lameter Acked-by: Mel Gorman --- mm/slub.c | 42 ++++++++++++++++++++++++++++-------------- 1 file changed, 28 insertions(+), 14 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index f928607230b2..92c3ab3a95ba 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -448,6 +448,18 @@ static inline bool cmpxchg_double_slab(struct kmem_c= ache *s, struct page *page, static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)]; static DEFINE_SPINLOCK(object_map_lock); =20 +static void __fill_map(unsigned long *obj_map, struct kmem_cache *s, + struct page *page) +{ + void *addr =3D page_address(page); + void *p; + + bitmap_zero(obj_map, page->objects); + + for (p =3D page->freelist; p; p =3D get_freepointer(s, p)) + set_bit(__obj_to_index(s, addr, p), obj_map); +} + /* * Determine a map of object in use on a page. * @@ -457,17 +469,11 @@ static DEFINE_SPINLOCK(object_map_lock); static unsigned long *get_map(struct kmem_cache *s, struct page *page) __acquires(&object_map_lock) { - void *p; - void *addr =3D page_address(page); - VM_BUG_ON(!irqs_disabled()); =20 spin_lock(&object_map_lock); =20 - bitmap_zero(object_map, page->objects); - - for (p =3D page->freelist; p; p =3D get_freepointer(s, p)) - set_bit(__obj_to_index(s, addr, p), object_map); + __fill_map(object_map, s, page); =20 return object_map; } @@ -4813,17 +4819,17 @@ static int add_location(struct loc_track *t, stru= ct kmem_cache *s, } =20 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 =3D page_address(page); void *p; - unsigned long *map; =20 - map =3D 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); } =20 static int list_locations(struct kmem_cache *s, char *buf, @@ -4834,9 +4840,15 @@ static int list_locations(struct kmem_cache *s, ch= ar *buf, struct loc_track t =3D { 0, 0, NULL }; int node; struct kmem_cache_node *n; + unsigned long *obj_map; + + obj_map =3D bitmap_alloc(oo_objects(s->oo), GFP_KERNEL); + if (!obj_map) + return sysfs_emit(buf, "Out of memory\n"); =20 if (!alloc_loc_track(&t, PAGE_SIZE / sizeof(struct location), GFP_KERNEL)) { + bitmap_free(obj_map); return sysfs_emit(buf, "Out of memory\n"); } =20 @@ -4849,12 +4861,14 @@ static int list_locations(struct kmem_cache *s, c= har *buf, =20 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); } =20 + bitmap_free(obj_map); + for (i =3D 0; i < t.count; i++) { struct location *l =3D &t.loc[i]; =20 --=20 2.31.1