Date: Tue, 3 Nov 2015 17:33:25 -0600 (CST)
From: Christoph Lameter <cl@linux.com>
To: Catalin Marinas <catalin.marinas@arm.com>
cc: Geert Uytterhoeven <geert@linux-m68k.org>,
        Robert Richter <rric@kernel.org>,
        Linux-sh list <linux-sh@vger.kernel.org>,
        Will Deacon <will.deacon@arm.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Robert Richter <rrichter@cavium.com>,
        Tirumalesh Chalamarla <tchalamarla@cavium.com>,
        "linux-arm-kernel@lists.infradead.org" 
	<linux-arm-kernel@lists.infradead.org>,
        Joonsoo Kim <js1304@gmail.com>
Subject: Re: [PATCH] arm64: Increase the max granular size
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On Tue, 3 Nov 2015, Catalin Marinas wrote:

> (cc'ing Jonsoo and Christoph; summary: slab failure with L1_CACHE_BYTES
> of 128 and sizeof(kmem_cache_node) of 152)

Hmmm... Yes that would mean use the 196 sized kmalloc array which is not a
power of two slab. But the code looks fine to me.

> If I revert commit 8fc9cf420b36 ("slab: make more slab management
> structure off the slab") it works but I still need to figure out how
> slab indices are calculated. The size_index[] array is overridden so
> that 0..15 are 7 and 16..23 are 8. But the kmalloc_caches[7] has never
> been populated, hence the BUG_ON. Another option may be to change
> kmalloc_size and kmalloc_index to cope with KMALLOC_MIN_SIZE of 128.
>
> I'll do some more investigation tomorrow.

The commit allows off slab management for PAGE_SIZE >> 5 that is 128.

After that commit kmem_cache_create would try to allocate an off slab
management structure which is not available during early boot.
But the slab_early_init is set which should prevent the use of an off slab
management infrastructure in kmem_cache_create().

However, the failure in line 2283 shows that the OFF SLAB flag was
mistakenly set anyways!!!! Something must havee cleared slab_early_init?


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