From: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Sachin Sant <sachinp@linux.vnet.ibm.com>,
Michal Hocko <mhocko@kernel.org>,
linux-mm@kvack.org, Kirill Tkhai <ktkhai@virtuozzo.com>,
Mel Gorman <mgorman@suse.de>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
Bharata B Rao <bharata@linux.ibm.com>,
linuxppc-dev@lists.ozlabs.org, Christopher Lameter <cl@linux.com>
Subject: Re: [PATCH 2/4] mm/slub: Use mem_node to allocate a new slab
Date: Tue, 17 Mar 2020 19:15:23 +0530 [thread overview]
Message-ID: <20200317134523.GB4334@linux.vnet.ibm.com> (raw)
In-Reply-To: <ef34b0bb-4dfa-cb0e-1830-9ad59119da5e@suse.cz>
* Vlastimil Babka <vbabka@suse.cz> [2020-03-17 14:34:25]:
> On 3/17/20 2:17 PM, Srikar Dronamraju wrote:
> > Currently while allocating a slab for a offline node, we use its
> > associated node_numa_mem to search for a partial slab. If we don't find
> > a partial slab, we try allocating a slab from the offline node using
> > __alloc_pages_node. However this is bound to fail.
> >
> > NIP [c00000000039a300] __alloc_pages_nodemask+0x130/0x3b0
> > LR [c00000000039a3c4] __alloc_pages_nodemask+0x1f4/0x3b0
> > Call Trace:
> > [c0000008b36837f0] [c00000000039a3b4] __alloc_pages_nodemask+0x1e4/0x3b0 (unreliable)
> > [c0000008b3683870] [c0000000003d1ff8] new_slab+0x128/0xcf0
> > [c0000008b3683950] [c0000000003d6060] ___slab_alloc+0x410/0x820
> > [c0000008b3683a40] [c0000000003d64a4] __slab_alloc+0x34/0x60
> > [c0000008b3683a70] [c0000000003d78b0] __kmalloc_node+0x110/0x490
> > [c0000008b3683af0] [c000000000343a08] kvmalloc_node+0x58/0x110
> > [c0000008b3683b30] [c0000000003ffd44] mem_cgroup_css_online+0x104/0x270
> > [c0000008b3683b90] [c000000000234e08] online_css+0x48/0xd0
> > [c0000008b3683bc0] [c00000000023dedc] cgroup_apply_control_enable+0x2ec/0x4d0
> > [c0000008b3683ca0] [c0000000002416f8] cgroup_mkdir+0x228/0x5f0
> > [c0000008b3683d10] [c000000000520360] kernfs_iop_mkdir+0x90/0xf0
> > [c0000008b3683d50] [c00000000043e400] vfs_mkdir+0x110/0x230
> > [c0000008b3683da0] [c000000000441ee0] do_mkdirat+0xb0/0x1a0
> > [c0000008b3683e20] [c00000000000b278] system_call+0x5c/0x68
> >
> > Mitigate this by allocating the new slab from the node_numa_mem.
>
> Are you sure this is really needed and the other 3 patches are not enough for
> the current SLUB code to work as needed? It seems you are changing the semantics
> here...
>
The other 3 patches are not enough because we don't carry the searchnode
when the actual alloc_pages_node gets called.
With only the 3 patches, we see the above Panic, its signature is slightly
different from what Sachin first reported and which I have carried in 1st
patch.
> > --- a/mm/slub.c
> > +++ b/mm/slub.c
> > @@ -1970,14 +1970,8 @@ static void *get_partial(struct kmem_cache *s, gfp_t flags, int node,
> > struct kmem_cache_cpu *c)
> > {
> > void *object;
> > - int searchnode = node;
> >
> > - if (node == NUMA_NO_NODE)
> > - searchnode = numa_mem_id();
> > - else if (!node_present_pages(node))
> > - searchnode = node_to_mem_node(node);
> > -
> > - object = get_partial_node(s, get_node(s, searchnode), c, flags);
> > + object = get_partial_node(s, get_node(s, node), c, flags);
> > if (object || node != NUMA_NO_NODE)> return object;
> >
> > return get_any_partial(s, flags, c);
>
> I.e. here in this if(), now node will never equal NUMA_NO_NODE (thanks to the
> hunk below), thus the get_any_partial() call becomes dead code?
>
> > @@ -2470,6 +2464,11 @@ static inline void *new_slab_objects(struct kmem_cache *s, gfp_t flags,
> >
> > WARN_ON_ONCE(s->ctor && (flags & __GFP_ZERO));
> >
> > + if (node == NUMA_NO_NODE)
> > + node = numa_mem_id();
> > + else if (!node_present_pages(node))
> > + node = node_to_mem_node(node);
> > +
> > freelist = get_partial(s, flags, node, c);
> >
> > if (freelist)
> > @@ -2569,12 +2568,10 @@ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
> > redo:
> >
> > if (unlikely(!node_match(page, node))) {
> > - int searchnode = node;
> > -
> > if (node != NUMA_NO_NODE && !node_present_pages(node))
> > - searchnode = node_to_mem_node(node);
> > + node = node_to_mem_node(node);
> >
> > - if (unlikely(!node_match(page, searchnode))) {
> > + if (unlikely(!node_match(page, node))) {
> > stat(s, ALLOC_NODE_MISMATCH);
> > deactivate_slab(s, page, c->freelist, c);
> > goto new_slab;
> >
>
--
Thanks and Regards
Srikar Dronamraju
next prev parent reply other threads:[~2020-03-17 14:47 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-18 10:45 [5.6.0-rc2-next-20200218/powerpc] Boot failure on POWER9 Sachin Sant
2020-02-18 10:50 ` Kirill Tkhai
2020-02-18 11:01 ` Kirill Tkhai
2020-02-18 11:35 ` Kirill Tkhai
2020-02-18 11:40 ` Sachin Sant
2020-02-18 11:55 ` Michal Hocko
2020-02-18 14:00 ` Sachin Sant
2020-02-18 14:26 ` Michal Hocko
2020-02-18 15:11 ` Sachin Sant
2020-02-18 15:24 ` Michal Hocko
2020-02-22 3:38 ` Christopher Lameter
2020-02-24 8:58 ` Michal Hocko
2020-02-26 18:25 ` Christopher Lameter
2020-02-26 18:41 ` Michal Hocko
2020-02-26 18:44 ` Christopher Lameter
2020-02-26 19:01 ` Michal Hocko
2020-02-26 20:31 ` David Rientjes
2020-02-26 20:52 ` Michal Hocko
2020-02-26 21:45 ` Vlastimil Babka
2020-02-26 22:29 ` Vlastimil Babka
2020-02-27 12:12 ` Michal Hocko
2020-02-27 16:00 ` Sachin Sant
2020-02-27 16:16 ` Vlastimil Babka
2020-02-27 18:26 ` Michal Hocko
2020-03-10 15:01 ` Michal Hocko
2020-03-12 12:18 ` Michael Ellerman
2020-03-12 16:51 ` Sachin Sant
2020-03-13 10:48 ` Michael Ellerman
2020-03-13 11:12 ` Srikar Dronamraju
2020-03-13 11:35 ` Vlastimil Babka
2020-03-14 8:10 ` Sachin Sant
2020-02-27 12:02 ` Michal Hocko
2020-02-18 11:38 ` Sachin Sant
2020-02-18 11:53 ` Kirill Tkhai
2020-03-17 13:17 ` [PATCH 0/4] Fix kmalloc_node on offline nodes Srikar Dronamraju
2020-03-17 13:17 ` [PATCH 1/4] mm: Check for node_online in node_present_pages Srikar Dronamraju
2020-03-17 13:37 ` Srikar Dronamraju
2020-03-17 13:17 ` [PATCH 2/4] mm/slub: Use mem_node to allocate a new slab Srikar Dronamraju
2020-03-17 13:34 ` Vlastimil Babka
2020-03-17 13:45 ` Srikar Dronamraju [this message]
2020-03-17 13:53 ` Vlastimil Babka
2020-03-17 14:51 ` Srikar Dronamraju
2020-03-17 15:29 ` Vlastimil Babka
2020-03-18 7:29 ` Srikar Dronamraju
2020-03-17 16:41 ` Srikar Dronamraju
2020-03-17 13:17 ` [PATCH 3/4] mm: Implement reset_numa_mem Srikar Dronamraju
2020-03-17 13:17 ` [PATCH 4/4] powerpc/numa: Set fallback nodes for offline nodes Srikar Dronamraju
2020-03-17 14:22 ` Bharata B Rao
2020-03-17 14:29 ` Srikar Dronamraju
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