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Message-ID: <1394424557.3607.4.camel@edumazet-glaptop2.roam.corp.google.com>
Date: Sun, 09 Mar 2014 21:09:17 -0700
From: Eric Dumazet <eric.dumazet@...il.com>
To: Jakub Kicinski <moorray3@...pl>
Cc: netdev@...r.kernel.org, Fan Du <fan.du@...driver.com>,
Steffen Klassert <steffen.klassert@...unet.com>
Subject: Re: net-next: NULL pointer dereference on adding a net namespace
and a system freeze
On Sun, 2014-03-09 at 21:02 -0700, Eric Dumazet wrote:
> On Mon, 2014-03-10 at 01:44 +0100, Jakub Kicinski wrote:
> > Hi!
> >
> > Running Fedora 20 with net-next I get the following warning when
> > libvirt or rtkit comes up:
> >
> > [ 272.143488] kmem_cache_sanity_check (flow_cache): Cache name already exists.
> > [ 272.143586] CPU: 0 PID: 975 Comm: libvirtd Not tainted 3.14.0-rc5+ #1
> > [ 272.143589] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
> > [ 272.143591] 0000000000000000 ffff88003ceadba0 ffffffff8167baf0 ffff88003db3d300
> > [ 272.143595] ffff88003ceadc18 ffffffff8117795b ffff88003ceadbc8 ffff88003b235158
> > [ 272.143599] 0000000000000000 0000000000040000 0000000000000068 0000000000000000
> > [ 272.143602] Call Trace:
> > [ 272.143610] [<ffffffff8167baf0>] dump_stack+0x4d/0x66
> > [ 272.143615] [<ffffffff8117795b>] kmem_cache_create_memcg+0x12b/0x420
> > [ 272.143618] [<ffffffff81177c7b>] kmem_cache_create+0x2b/0x30
> > [ 272.143622] [<ffffffff815c4a0e>] flow_cache_init+0x2e/0x2b0
> > [ 272.143626] [<ffffffff8164b017>] xfrm_net_init+0x227/0x360
> > [ 272.143629] [<ffffffff8164af41>] ? xfrm_net_init+0x151/0x360
> > [ 272.143632] [<ffffffff815a5921>] ops_init+0x41/0x150
> > [ 272.143635] [<ffffffff815a5aa3>] setup_net+0x73/0x110
> > [ 272.143638] [<ffffffff815a5fe2>] copy_net_ns+0x72/0x100
> > [ 272.143642] [<ffffffff810943f9>] create_new_namespaces+0xf9/0x190
> > [ 272.143645] [<ffffffff81094560>] copy_namespaces+0xd0/0xf0
> > [ 272.143648] [<ffffffff81094495>] ? copy_namespaces+0x5/0xf0
> > [ 272.143651] [<ffffffff81069be0>] copy_process.part.31+0x950/0x1b30
> > [ 272.143655] [<ffffffff8106af95>] do_fork+0xd5/0x370
> > [ 272.143658] [<ffffffff811c1b2d>] ? __fput+0x17d/0x240
> > [ 272.143662] [<ffffffff8110440c>] ? __audit_syscall_entry+0x9c/0xf0
> > [ 272.143665] [<ffffffff8106b2b6>] SyS_clone+0x16/0x20
> > [ 272.143669] [<ffffffff8168cf19>] stub_clone+0x69/0x90
> > [ 272.143673] [<ffffffff8168cb69>] ? system_call_fastpath+0x16/0x1b
> >
> >
> > When I try to add a netns with
> > # ip netns add abcd
> > I it dies with:
>
>
> Yep, commit ca925cf1534ebcec332c08719a7dee6ee1782ce4 is buggy.
>
> flowcache: Make flow cache name space aware
>
> Inserting a entry into flowcache, or flushing flowcache should be based
> on per net scope. The reason to do so is flushing operation from fat
> netns crammed with flow entries will also making the slim netns with only
> a few flow cache entries go away in original implementation.
>
> Since flowcache is tightly coupled with IPsec, so it would be easier to
> put flow cache global parameters into xfrm namespace part. And one last
> thing needs to do is bumping flow cache genid, and flush flow cache should
> also be made in per net style.
>
> Signed-off-by: Fan Du <fan.du@...driver.com>
> Signed-off-by: Steffen Klassert <steffen.klassert@...unet.com>
>
> I fail to understand why the kmem_cache must be private to a netns.
Could you please try the following patch ?
diff --git a/include/net/netns/xfrm.h b/include/net/netns/xfrm.h
index 51f0dce7b643..3492434baf88 100644
--- a/include/net/netns/xfrm.h
+++ b/include/net/netns/xfrm.h
@@ -64,7 +64,6 @@ struct netns_xfrm {
/* flow cache part */
struct flow_cache flow_cache_global;
- struct kmem_cache *flow_cachep;
atomic_t flow_cache_genid;
struct list_head flow_cache_gc_list;
spinlock_t flow_cache_gc_lock;
diff --git a/net/core/flow.c b/net/core/flow.c
index 344a184011fd..102f8ea2eb6e 100644
--- a/net/core/flow.c
+++ b/net/core/flow.c
@@ -45,6 +45,8 @@ struct flow_flush_info {
struct completion completion;
};
+static struct kmem_cache *flow_cachep __read_mostly;
+
#define flow_cache_hash_size(cache) (1 << (cache)->hash_shift)
#define FLOW_HASH_RND_PERIOD (10 * 60 * HZ)
@@ -75,7 +77,7 @@ static void flow_entry_kill(struct flow_cache_entry *fle,
{
if (fle->object)
fle->object->ops->delete(fle->object);
- kmem_cache_free(xfrm->flow_cachep, fle);
+ kmem_cache_free(flow_cachep, fle);
}
static void flow_cache_gc_task(struct work_struct *work)
@@ -230,7 +232,7 @@ flow_cache_lookup(struct net *net, const struct flowi *key, u16 family, u8 dir,
if (fcp->hash_count > fc->high_watermark)
flow_cache_shrink(fc, fcp);
- fle = kmem_cache_alloc(net->xfrm.flow_cachep, GFP_ATOMIC);
+ fle = kmem_cache_alloc(flow_cachep, GFP_ATOMIC);
if (fle) {
fle->net = net;
fle->family = family;
@@ -435,10 +437,10 @@ int flow_cache_init(struct net *net)
int i;
struct flow_cache *fc = &net->xfrm.flow_cache_global;
- /* Initialize per-net flow cache global variables here */
- net->xfrm.flow_cachep = kmem_cache_create("flow_cache",
- sizeof(struct flow_cache_entry),
- 0, SLAB_PANIC, NULL);
+ if (!flow_cachep)
+ flow_cachep = kmem_cache_create("flow_cache",
+ sizeof(struct flow_cache_entry),
+ 0, SLAB_PANIC, NULL);
spin_lock_init(&net->xfrm.flow_cache_gc_lock);
INIT_LIST_HEAD(&net->xfrm.flow_cache_gc_list);
INIT_WORK(&net->xfrm.flow_cache_gc_work, flow_cache_gc_task);
--
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