linux-kernel - Re: [patch 00/12] Slab defragmentation V3

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Date:	Fri, 08 Jun 2007 21:47:38 +0200
From:	Michal Piotrowski <michal.k.k.piotrowski@...il.com>
To:	Christoph Lameter <clameter@....com>
CC:	Michal Piotrowski <michal.k.k.piotrowski@...il.com>,
	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, dgc@....com, Mel Gorman <mel@...net.ie>
Subject: Re: [patch 00/12] Slab defragmentation V3

Christoph Lameter pisze:
> On Fri, 8 Jun 2007, Christoph Lameter wrote:
> 
>> On Fri, 8 Jun 2007, Michal Piotrowski wrote:
>>
>>> Yes, it does. Thanks!
>> Ahhh... That leds to the discovery more sysfs problems. I need to make 
>> sure not to be holding locks while calling into sysfs. More cleanup...
> 
> Could you remove the trylock patch and see how this one fares? We may need 
> both but this should avoid taking the slub_lock around any possible alloc 
> of sysfs.
> 
> 

It's a bit tricky

cat ../sd2.patch | patch -p1
patching file mm/slub.c
Hunk #1 succeeded at 2194 (offset 15 lines).
Hunk #2 FAILED at 2653.
1 out of 2 hunks FAILED -- saving rejects to file mm/slub.c.rej
[michal@...is-gabonica linux-work3]$ cat mm/slub.c.rej
***************
*** 2652,2677 ****
                 */
                s->objsize = max(s->objsize, (int)size);
                s->inuse = max_t(int, s->inuse, ALIGN(size, sizeof(void *)));
                if (sysfs_slab_alias(s, name))
                        goto err;
-       } else {
-               s = kmalloc(kmem_size, GFP_KERNEL);
-               if (s && kmem_cache_open(s, GFP_KERNEL, name,
                                size, align, flags, ctor)) {
-                       if (sysfs_slab_add(s)) {
-                               kfree(s);
-                               goto err;
-                       }
                        list_add(&s->list, &slab_caches);
                        raise_kswapd_order(s->order);
-               } else
-                       kfree(s);
        }
        up_write(&slub_lock);
-       return s;

  err:
-       up_write(&slub_lock);
        if (flags & SLAB_PANIC)
                panic("Cannot create slabcache %s\n", name);
        else
--- 2653,2685 ----
                 */
                s->objsize = max(s->objsize, (int)size);
                s->inuse = max_t(int, s->inuse, ALIGN(size, sizeof(void *)));
+               up_write(&slub_lock);
+
                if (sysfs_slab_alias(s, name))
                        goto err;
+
+               return s;
+       }
+
+       s = kmalloc(kmem_size, GFP_KERNEL);
+       if (s) {
+               if (kmem_cache_open(s, GFP_KERNEL, name,
                                size, align, flags, ctor)) {
                        list_add(&s->list, &slab_caches);
+                       up_write(&slub_lock);
                        raise_kswapd_order(s->order);
+
+                       if (sysfs_slab_add(s))
+                               goto err;
+
+                       return s;
+
+               }
+               kfree(s);
        }
        up_write(&slub_lock);

  err:
        if (flags & SLAB_PANIC)
                panic("Cannot create slabcache %s\n", name);
        else

Regards,
Michal

-- 
"Najbardziej brakowało mi twojego milczenia."
-- Andrzej Sapkowski "Coś więcej"
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