Re: [PATCH 1/2] mm: Allow disabling deferred struct page initialisation

On 08/02/2016 11:38 PM, Srikar Dronamraju wrote:

* Dave Hansen [off-list ref] [2016-08-02 11:09:21]:

quoted

On 08/02/2016 06:19 AM, Srikar Dronamraju wrote:

quoted

Kernels compiled with CONFIG_DEFERRED_STRUCT_PAGE_INIT will initialise
only certain size memory per node. The certain size takes into account
the dentry and inode cache sizes. However such a kernel when booting a
secondary kernel will not be able to allocate the required amount of
memory to suffice for the dentry and inode caches. This results in
crashes like the below on large systems such as 32 TB systems.

What's a "secondary kernel"?

I mean the kernel thats booted to collect the crash, On fadump, the
first kernel acts as the secondary kernel i.e the same kernel is booted
to collect the crash.

OK, but I'm still not seeing what the problem is.  You've said that it
crashes and that it crashes during inode/dentry cache allocation.

But, *why* does the same kernel image crash in when it is used as a
"secondary kernel"?