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Groups > linux.kernel > #1365320 > unrolled thread
| Started by | js1304@gmail.com |
|---|---|
| First post | 2016-03-28 07:30 +0200 |
| Last post | 2016-03-29 03:00 +0200 |
| Articles | 5 — 5 participants |
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[PATCH 02/11] mm/slab: remove BAD_ALIEN_MAGIC again js1304@gmail.com - 2016-03-28 07:30 +0200
Re: [PATCH 02/11] mm/slab: remove BAD_ALIEN_MAGIC again Geert Uytterhoeven <geert@linux-m68k.org> - 2016-03-28 11:00 +0200
Re: [PATCH 02/11] mm/slab: remove BAD_ALIEN_MAGIC again Joonsoo Kim <iamjoonsoo.kim@lge.com> - 2016-03-30 10:10 +0200
Re: [PATCH 02/11] mm/slab: remove BAD_ALIEN_MAGIC again Andrew Morton <akpm@linux-foundation.org> - 2016-03-28 23:20 +0200
Re: [PATCH 02/11] mm/slab: remove BAD_ALIEN_MAGIC again Christoph Lameter <cl@linux.com> - 2016-03-29 03:00 +0200
| From | js1304@gmail.com |
|---|---|
| Date | 2016-03-28 07:30 +0200 |
| Subject | [PATCH 02/11] mm/slab: remove BAD_ALIEN_MAGIC again |
| Message-ID | <rhxUv-2rs-23@gated-at.bofh.it> |
From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Initial attemp to remove BAD_ALIEN_MAGIC is once reverted by
'commit edcad2509550 ("Revert "slab: remove BAD_ALIEN_MAGIC"")'
because it causes a problem on m68k which has many node
but !CONFIG_NUMA. In this case, although alien cache isn't used
at all but to cope with some initialization path, garbage value
is used and that is BAD_ALIEN_MAGIC. Now, this patch set
use_alien_caches to 0 when !CONFIG_NUMA, there is no initialization
path problem so we don't need BAD_ALIEN_MAGIC at all. So remove it.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
---
mm/slab.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
diff --git a/mm/slab.c b/mm/slab.c
index 043606a..a5a205b 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -421,8 +421,6 @@ static struct kmem_cache kmem_cache_boot = {
.name = "kmem_cache",
};
-#define BAD_ALIEN_MAGIC 0x01020304ul
-
static DEFINE_PER_CPU(struct delayed_work, slab_reap_work);
static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)
@@ -637,7 +635,7 @@ static int transfer_objects(struct array_cache *to,
static inline struct alien_cache **alloc_alien_cache(int node,
int limit, gfp_t gfp)
{
- return (struct alien_cache **)BAD_ALIEN_MAGIC;
+ return NULL;
}
static inline void free_alien_cache(struct alien_cache **ac_ptr)
@@ -1205,7 +1203,7 @@ void __init kmem_cache_init(void)
sizeof(struct rcu_head));
kmem_cache = &kmem_cache_boot;
- if (num_possible_nodes() == 1)
+ if (!IS_ENABLED(CONFIG_NUMA) || num_possible_nodes() == 1)
use_alien_caches = 0;
for (i = 0; i < NUM_INIT_LISTS; i++)
--
1.9.1
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| From | Geert Uytterhoeven <geert@linux-m68k.org> |
|---|---|
| Date | 2016-03-28 11:00 +0200 |
| Message-ID | <rhBbH-4sP-9@gated-at.bofh.it> |
| In reply to | #1365320 |
Hi Jonsoo,
On Mon, Mar 28, 2016 at 7:26 AM, <js1304@gmail.com> wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>
> Initial attemp to remove BAD_ALIEN_MAGIC is once reverted by
> 'commit edcad2509550 ("Revert "slab: remove BAD_ALIEN_MAGIC"")'
> because it causes a problem on m68k which has many node
> but !CONFIG_NUMA. In this case, although alien cache isn't used
> at all but to cope with some initialization path, garbage value
> is used and that is BAD_ALIEN_MAGIC. Now, this patch set
> use_alien_caches to 0 when !CONFIG_NUMA, there is no initialization
> path problem so we don't need BAD_ALIEN_MAGIC at all. So remove it.
>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
I gave this a try on m68k/ARAnyM, and it didn't crash, unlike the previous
version that was reverted, so
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
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| From | Joonsoo Kim <iamjoonsoo.kim@lge.com> |
|---|---|
| Date | 2016-03-30 10:10 +0200 |
| Message-ID | <rijmp-2uB-3@gated-at.bofh.it> |
| In reply to | #1365393 |
On Mon, Mar 28, 2016 at 10:58:38AM +0200, Geert Uytterhoeven wrote:
> Hi Jonsoo,
>
> On Mon, Mar 28, 2016 at 7:26 AM, <js1304@gmail.com> wrote:
> > From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> >
> > Initial attemp to remove BAD_ALIEN_MAGIC is once reverted by
> > 'commit edcad2509550 ("Revert "slab: remove BAD_ALIEN_MAGIC"")'
> > because it causes a problem on m68k which has many node
> > but !CONFIG_NUMA. In this case, although alien cache isn't used
> > at all but to cope with some initialization path, garbage value
> > is used and that is BAD_ALIEN_MAGIC. Now, this patch set
> > use_alien_caches to 0 when !CONFIG_NUMA, there is no initialization
> > path problem so we don't need BAD_ALIEN_MAGIC at all. So remove it.
> >
> > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>
> I gave this a try on m68k/ARAnyM, and it didn't crash, unlike the previous
> version that was reverted, so
> Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Thanks for testing!!!
Thanks.
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| From | Andrew Morton <akpm@linux-foundation.org> |
|---|---|
| Date | 2016-03-28 23:20 +0200 |
| Message-ID | <rhMJQ-4ie-21@gated-at.bofh.it> |
| In reply to | #1365320 |
On Mon, 28 Mar 2016 14:26:52 +0900 js1304@gmail.com wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>
> Initial attemp to remove BAD_ALIEN_MAGIC is once reverted by
> 'commit edcad2509550 ("Revert "slab: remove BAD_ALIEN_MAGIC"")'
> because it causes a problem on m68k which has many node
> but !CONFIG_NUMA.
Whaaa? How is that even possible? I'd have thought that everything
would break at compile time (at least) with such a setup.
> In this case, although alien cache isn't used
> at all but to cope with some initialization path, garbage value
> is used and that is BAD_ALIEN_MAGIC. Now, this patch set
> use_alien_caches to 0 when !CONFIG_NUMA, there is no initialization
> path problem so we don't need BAD_ALIEN_MAGIC at all. So remove it.
>
> ...
>
> @@ -1205,7 +1203,7 @@ void __init kmem_cache_init(void)
> sizeof(struct rcu_head));
> kmem_cache = &kmem_cache_boot;
>
> - if (num_possible_nodes() == 1)
> + if (!IS_ENABLED(CONFIG_NUMA) || num_possible_nodes() == 1)
> use_alien_caches = 0;
>
> for (i = 0; i < NUM_INIT_LISTS; i++)
This does look screwy. How can num_possible_nodes() possibly return
anything but "1" if CONFIG_NUMA=n.
Can we please get a code comment in here to explain things to the poor
old reader and to prevent people from trying to "fix" it?
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| From | Christoph Lameter <cl@linux.com> |
|---|---|
| Date | 2016-03-29 03:00 +0200 |
| Message-ID | <rhQaK-6GM-5@gated-at.bofh.it> |
| In reply to | #1365680 |
On Mon, 28 Mar 2016, Andrew Morton wrote:
> On Mon, 28 Mar 2016 14:26:52 +0900 js1304@gmail.com wrote:
>
> > From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> >
> > Initial attemp to remove BAD_ALIEN_MAGIC is once reverted by
> > 'commit edcad2509550 ("Revert "slab: remove BAD_ALIEN_MAGIC"")'
> > because it causes a problem on m68k which has many node
> > but !CONFIG_NUMA.
>
> Whaaa? How is that even possible? I'd have thought that everything
> would break at compile time (at least) with such a setup.
Yes we have that and the support for this caused numerous issues. Can we
stop supporting such a configuration?
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