On Fri, Jul 22, 2016 at 08:51:02PM +0900, Tetsuo Handa wrote:
> Joonsoo Kim wrote:
> > @@ -3313,6 +3310,14 @@ static void free_block(struct kmem_cache *cachep, void **objpp,
> > list_add_tail(&page->lru, &n->slabs_partial);
> > }
> > }
> > +
> > + while (n->free_objects > n->free_limit && !list_empty(&n->slabs_free)) {
> > + n->free_objects -= cachep->num;
> > +
> > + page = list_last_entry(&n->slabs_free, struct page, lru);
> > + list_del(&page->lru);
> > + list_add(&page->lru, list);
> > + }
> > }
> >
> > static void cache_flusharray(struct kmem_cache *cachep, struct array_cache *ac)
> >
>
> I noticed that kmemcheck complains that n->free_limit is not initialized.
>
> [ 0.000000] Console: colour VGA+ 80x25
> [ 0.000000] console [tty0] enabled
> [ 0.000000] console [ttyS0] enabled
> [ 0.000000] WARNING: kmemcheck: Caught 32-bit read from uninitialized memory (ffff88013ec085b8)
> [ 0.000000] a085c03e0188ffffa085c03e0188ffff06000000000000000000000000000000
> [ 0.000000] i i i i i i i i i i i i i i i i i i i i i i i i u u u u i i i i
> [ 0.000000] ^
> [ 0.000000] RIP: 0010:[<ffffffff8113073e>] [<ffffffff8113073e>] free_block+0x14e/0x1d0
> [ 0.000000] RSP: 0000:ffffffff81803e58 EFLAGS: 00010046
> [ 0.000000] RAX: 0000000000000006 RBX: ffff88013ec0c000 RCX: 0000000000000000
> [ 0.000000] RDX: 0000000000000000 RSI: ffff88013f7c5418 RDI: ffff88013ec0c000
> [ 0.000000] RBP: ffffffff81803e88 R08: ffffffff81803ea0 R09: ffff88013ec08580
> [ 0.000000] R10: ffff88013f7c55d0 R11: 00000000000005cd R12: ffff88013f7c5408
> [ 0.000000] R13: ffffffff81803ea0 R14: 0000000002000000 R15: 000000000000001b
> [ 0.000000] FS: 0000000000000000(0000) GS:ffffffff8182c000(0000) knlGS:0000000000000000
> [ 0.000000] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 0.000000] CR2: ffff88013e800000 CR3: 000000000180c000 CR4: 00000000000406b0
> [ 0.000000] [<ffffffff81131a84>] __do_tune_cpucache+0x84/0x310
> [ 0.000000] [<ffffffff81131d35>] do_tune_cpucache+0x25/0x90
> [ 0.000000] [<ffffffff81131df0>] enable_cpucache+0x50/0xc0
> [ 0.000000] [<ffffffff818b5c70>] kmem_cache_init_late+0x3f/0x68
> [ 0.000000] [<ffffffff81895eda>] start_kernel+0x2f2/0x48d
> [ 0.000000] [<ffffffff8189553a>] x86_64_start_reservations+0x2f/0x31
> [ 0.000000] [<ffffffff81895632>] x86_64_start_kernel+0xf6/0x111
> [ 0.000000] [<ffffffffffffffff>] 0xffffffffffffffff
> [ 0.000000] tsc: Unable to calibrate against PIT
> [ 0.000000] tsc: using PMTIMER reference calibration
> [ 0.000000] tsc: Detected 2793.551 MHz processor
>
> Setting 0 at kmem_cache_node_init() fixes the problem, but what the initial
> value should be? (Since list_empty(&n->slabs_free) == true, uninitialized
> read of n->free_limit does not cause problems except kmemcheck.)
Setting 0 would be okay because it would mean that we don't want to cache any
object on kmem_cache_node. We will re-initialize it soon so it doesn't
cause any problem.
Thanks.
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