From: Christoph Lameter <cl@linux-foundation.org>
To: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Nick Piggin <npiggin@suse.de>, Tejun Heo <tj@kernel.org>
Subject: Re: [S+Q3 00/23] SLUB: The Unified slab allocator (V3)
Date: Tue, 17 Aug 2010 12:23:04 -0500 (CDT) [thread overview]
Message-ID: <alpine.DEB.2.00.1008171217440.11915@router.home> (raw)
In-Reply-To: <alpine.DEB.2.00.1008151627450.27137@chino.kir.corp.google.com>
On Mon, 16 Aug 2010, David Rientjes wrote:
> Ok, so this is panicking because of the error handling when trying to
> create sysfs directories with the same name (in this case, :dt-0000064).
> I'll look into while this isn't failing gracefully later, but I isolated
> this to the new code that statically allocates the DMA caches in
> kmem_cache_init_late().
Hmm.... Strange. The DMA caches should create a distinct pattern there.
> The iteration runs from 0 to SLUB_PAGE_SHIFT; that's actually incorrect
> since the kmem_cache_node cache occupies the first spot in the
> kmalloc_caches array and has a size, 64 bytes, equal to a power of two
> that is duplicated later. So this patch tries creating two DMA kmalloc
> caches with 64 byte object size which triggers a BUG_ON() during
> kmem_cache_release() in the error handling later.
The kmem_cache_node cache is no longer at position 0.
kmalloc_caches[0] should be NULL and therefore be skipped.
> The fix is to start the iteration at 1 instead of 0 so that all other
> caches have their equivalent DMA caches created and the special-case
> kmem_cache_node cache is excluded (see below).
>
> I'm really curious why nobody else ran into this problem before,
> especially if they have CONFIG_SLUB_DEBUG enabled so
> struct kmem_cache_node has the same size. Perhaps my early bug report
> caused people not to test the series...
Which patches were applied?
> - the entire iteration in kmem_cache_init_late() needs to be protected by
> slub_lock. The comment in create_kmalloc_cache() should be revised
> since you're no longer calling it only with irqs disabled.
> kmem_cache_init_late() has irqs enabled and, thus, slab_caches must be
> protected.
I moved it to kmem_cache_init() which is run when we only have one
execution thread. That takes care of the issue and ensures that the dma
caches are available as early as before.
> - a BUG_ON(!name) needs to be added in kmem_cache_init_late() when
> kasprintf() returns NULL. This isn't checked in kmem_cache_open() so
> it'll only encounter a problem in the sysfs layer. Adding a BUG_ON()
> will help track those down.
Ok.
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next prev parent reply other threads:[~2010-08-17 17:23 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-04 2:45 [S+Q3 00/23] SLUB: The Unified slab allocator (V3) Christoph Lameter
2010-08-04 2:45 ` [S+Q3 01/23] percpu: make @dyn_size always mean min dyn_size in first chunk init functions Christoph Lameter
2010-08-04 2:45 ` [S+Q3 02/23] percpu: allow limited allocation before slab is online Christoph Lameter
2010-08-04 2:45 ` [S+Q3 03/23] slub: Use a constant for a unspecified node Christoph Lameter
2010-08-04 3:34 ` David Rientjes
2010-08-04 16:15 ` Christoph Lameter
2010-08-05 7:40 ` David Rientjes
2010-08-04 2:45 ` [S+Q3 04/23] SLUB: Constants need UL Christoph Lameter
2010-08-04 2:45 ` [S+Q3 05/23] Subjec Slub: Force no inlining of debug functions Christoph Lameter
2010-08-04 2:45 ` [S+Q3 06/23] slub: Check kasprintf results in kmem_cache_init() Christoph Lameter
2010-08-04 2:45 ` [S+Q3 07/23] slub: Use kmem_cache flags to detect if slab is in debugging mode Christoph Lameter
2010-08-04 2:45 ` [S+Q3 08/23] slub: remove dynamic dma slab allocation Christoph Lameter
2010-08-04 2:45 ` [S+Q3 09/23] slub: Remove static kmem_cache_cpu array for boot Christoph Lameter
2010-08-04 2:45 ` [S+Q3 10/23] slub: Allow removal of slab caches during boot V2 Christoph Lameter
2010-08-04 2:45 ` [S+Q3 11/23] slub: Dynamically size kmalloc cache allocations Christoph Lameter
2010-08-04 2:45 ` [S+Q3 12/23] slub: Extract hooks for memory checkers from hotpaths Christoph Lameter
2010-08-04 2:45 ` [S+Q3 13/23] slub: Move gfpflag masking out of the hotpath Christoph Lameter
2010-08-04 2:45 ` [S+Q3 14/23] slub: Add SLAB style per cpu queueing Christoph Lameter
2010-08-04 2:45 ` [S+Q3 15/23] slub: Allow resizing of per cpu queues Christoph Lameter
2010-08-04 2:45 ` [S+Q3 16/23] slub: Get rid of useless function count_free() Christoph Lameter
2010-08-04 2:45 ` [S+Q3 17/23] slub: Remove MAX_OBJS limitation Christoph Lameter
2010-08-04 2:45 ` [S+Q3 18/23] slub: Drop allocator announcement Christoph Lameter
2010-08-04 2:45 ` [S+Q3 19/23] slub: Object based NUMA policies Christoph Lameter
2010-08-04 2:45 ` [S+Q3 20/23] slub: Shared cache to exploit cross cpu caching abilities Christoph Lameter
2010-08-17 5:52 ` David Rientjes
2010-08-17 17:51 ` Christoph Lameter
2010-08-17 18:42 ` David Rientjes
2010-08-17 18:50 ` Christoph Lameter
2010-08-17 19:02 ` David Rientjes
2010-08-17 19:32 ` Christoph Lameter
2010-08-18 19:32 ` Christoph Lameter
2010-08-04 2:45 ` [S+Q3 21/23] slub: Support Alien Caches Christoph Lameter
2010-08-04 2:45 ` [S+Q3 22/23] slub: Cached object expiration Christoph Lameter
2010-08-04 2:45 ` [S+Q3 23/23] vmscan: Tie slub object expiration into page reclaim Christoph Lameter
2010-08-04 4:39 ` [S+Q3 00/23] SLUB: The Unified slab allocator (V3) David Rientjes
2010-08-04 16:17 ` Christoph Lameter
2010-08-05 8:38 ` David Rientjes
2010-08-05 17:33 ` Christoph Lameter
2010-08-17 4:56 ` David Rientjes
2010-08-17 7:55 ` Tejun Heo
2010-08-17 13:56 ` Christoph Lameter
2010-08-17 17:23 ` Christoph Lameter [this message]
2010-08-17 17:29 ` Christoph Lameter
2010-08-17 18:02 ` David Rientjes
2010-08-17 18:47 ` Christoph Lameter
2010-08-17 18:54 ` David Rientjes
2010-08-17 19:34 ` Christoph Lameter
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