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authorQian Cai <cai@lca.pw>2019-03-05 15:42:03 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2019-03-05 21:07:14 -0800
commit92d1d07daad65c300c7d0b68bbef8867e9895d54 (patch)
tree6b601883327d27ea4feebf9c9aabc8e76bd24669
parentedde82b6df70cf10486d7f1e1611151218e6c316 (diff)
mm/slab.c: kmemleak no scan alien caches
Kmemleak throws endless warnings during boot due to in __alloc_alien_cache(), alc = kmalloc_node(memsize, gfp, node); init_arraycache(&alc->ac, entries, batch); kmemleak_no_scan(ac); Kmemleak does not track the array cache (alc->ac) but the alien cache (alc) instead, so let it track the latter by lifting kmemleak_no_scan() out of init_arraycache(). There is another place that calls init_arraycache(), but alloc_kmem_cache_cpus() uses the percpu allocation where will never be considered as a leak. kmemleak: Found object by alias at 0xffff8007b9aa7e38 CPU: 190 PID: 1 Comm: swapper/0 Not tainted 5.0.0-rc2+ #2 Call trace: dump_backtrace+0x0/0x168 show_stack+0x24/0x30 dump_stack+0x88/0xb0 lookup_object+0x84/0xac find_and_get_object+0x84/0xe4 kmemleak_no_scan+0x74/0xf4 setup_kmem_cache_node+0x2b4/0x35c __do_tune_cpucache+0x250/0x2d4 do_tune_cpucache+0x4c/0xe4 enable_cpucache+0xc8/0x110 setup_cpu_cache+0x40/0x1b8 __kmem_cache_create+0x240/0x358 create_cache+0xc0/0x198 kmem_cache_create_usercopy+0x158/0x20c kmem_cache_create+0x50/0x64 fsnotify_init+0x58/0x6c do_one_initcall+0x194/0x388 kernel_init_freeable+0x668/0x688 kernel_init+0x18/0x124 ret_from_fork+0x10/0x18 kmemleak: Object 0xffff8007b9aa7e00 (size 256): kmemleak: comm "swapper/0", pid 1, jiffies 4294697137 kmemleak: min_count = 1 kmemleak: count = 0 kmemleak: flags = 0x1 kmemleak: checksum = 0 kmemleak: backtrace: kmemleak_alloc+0x84/0xb8 kmem_cache_alloc_node_trace+0x31c/0x3a0 __kmalloc_node+0x58/0x78 setup_kmem_cache_node+0x26c/0x35c __do_tune_cpucache+0x250/0x2d4 do_tune_cpucache+0x4c/0xe4 enable_cpucache+0xc8/0x110 setup_cpu_cache+0x40/0x1b8 __kmem_cache_create+0x240/0x358 create_cache+0xc0/0x198 kmem_cache_create_usercopy+0x158/0x20c kmem_cache_create+0x50/0x64 fsnotify_init+0x58/0x6c do_one_initcall+0x194/0x388 kernel_init_freeable+0x668/0x688 kernel_init+0x18/0x124 kmemleak: Not scanning unknown object at 0xffff8007b9aa7e38 CPU: 190 PID: 1 Comm: swapper/0 Not tainted 5.0.0-rc2+ #2 Call trace: dump_backtrace+0x0/0x168 show_stack+0x24/0x30 dump_stack+0x88/0xb0 kmemleak_no_scan+0x90/0xf4 setup_kmem_cache_node+0x2b4/0x35c __do_tune_cpucache+0x250/0x2d4 do_tune_cpucache+0x4c/0xe4 enable_cpucache+0xc8/0x110 setup_cpu_cache+0x40/0x1b8 __kmem_cache_create+0x240/0x358 create_cache+0xc0/0x198 kmem_cache_create_usercopy+0x158/0x20c kmem_cache_create+0x50/0x64 fsnotify_init+0x58/0x6c do_one_initcall+0x194/0x388 kernel_init_freeable+0x668/0x688 kernel_init+0x18/0x124 ret_from_fork+0x10/0x18 Link: http://lkml.kernel.org/r/20190129184518.39808-1-cai@lca.pw Fixes: 1fe00d50a9e8 ("slab: factor out initialization of array cache") Signed-off-by: Qian Cai <cai@lca.pw> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/slab.c17
1 files changed, 9 insertions, 8 deletions
diff --git a/mm/slab.c b/mm/slab.c
index 91c1863df93d..757e646baa5d 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -550,14 +550,6 @@ static void start_cpu_timer(int cpu)
static void init_arraycache(struct array_cache *ac, int limit, int batch)
{
- /*
- * The array_cache structures contain pointers to free object.
- * However, when such objects are allocated or transferred to another
- * cache the pointers are not cleared and they could be counted as
- * valid references during a kmemleak scan. Therefore, kmemleak must
- * not scan such objects.
- */
- kmemleak_no_scan(ac);
if (ac) {
ac->avail = 0;
ac->limit = limit;
@@ -573,6 +565,14 @@ static struct array_cache *alloc_arraycache(int node, int entries,
struct array_cache *ac = NULL;
ac = kmalloc_node(memsize, gfp, node);
+ /*
+ * The array_cache structures contain pointers to free object.
+ * However, when such objects are allocated or transferred to another
+ * cache the pointers are not cleared and they could be counted as
+ * valid references during a kmemleak scan. Therefore, kmemleak must
+ * not scan such objects.
+ */
+ kmemleak_no_scan(ac);
init_arraycache(ac, entries, batchcount);
return ac;
}
@@ -667,6 +667,7 @@ static struct alien_cache *__alloc_alien_cache(int node, int entries,
alc = kmalloc_node(memsize, gfp, node);
if (alc) {
+ kmemleak_no_scan(alc);
init_arraycache(&alc->ac, entries, batch);
spin_lock_init(&alc->lock);
}