linux-kernel - Re: [PATCH 09/24] mm/memblock: Add memblock memory allocation apis

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <529D2A6F.5050607@ti.com>
Date:	Mon, 2 Dec 2013 19:48:47 -0500
From:	Santosh Shilimkar <santosh.shilimkar@...com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	<tj@...nel.org>, <linux-kernel@...r.kernel.org>,
	<linux-mm@...ck.org>, <linux-arm-kernel@...ts.infradead.org>,
	Yinghai Lu <yinghai@...nel.org>,
	Grygorii Strashko <grygorii.strashko@...com>
Subject: Re: [PATCH 09/24] mm/memblock: Add memblock memory allocation apis

On Monday 02 December 2013 07:31 PM, Andrew Morton wrote:
> On Fri, 8 Nov 2013 18:41:45 -0500 Santosh Shilimkar <santosh.shilimkar@...com> wrote:
> 
>> Introduce memblock memory allocation APIs which allow to support
>> PAE or LPAE extension on 32 bits archs where the physical memory start
>> address can be beyond 4GB. In such cases, existing bootmem APIs which
>> operate on 32 bit addresses won't work and needs memblock layer which
>> operates on 64 bit addresses.
>>
>> So we add equivalent APIs so that we can replace usage of bootmem
>> with memblock interfaces. Architectures already converted to NO_BOOTMEM
>> use these new interfaces and other which still uses bootmem, these new
>> APIs just fallback to exiting bootmem APIs. So no functional change as
>> such.
>>
>> In long run, once all the achitectures moves to NO_BOOTMEM, we can get rid of
>> bootmem layer completely. This is one step to remove the core code dependency
>> with bootmem and also gives path for architectures to move away from bootmem.
>>
>> The proposed interface will became active if both CONFIG_HAVE_MEMBLOCK
>> and CONFIG_NO_BOOTMEM are specified by arch. In case !CONFIG_NO_BOOTMEM,
>> the memblock() wrappers will fallback to the existing bootmem apis so
>> that arch's not converted to NO_BOOTMEM continue to work as is.
>>
>> The meaning of MEMBLOCK_ALLOC_ACCESSIBLE and MEMBLOCK_ALLOC_ANYWHERE is
>> kept same.
>>
>> ...
>>
>> +static void * __init _memblock_virt_alloc_try_nid_nopanic(
>> +				phys_addr_t size, phys_addr_t align,
>> +				phys_addr_t from, phys_addr_t max_addr,
>> +				int nid)
>> +{
>> +	phys_addr_t alloc;
>> +	void *ptr;
>> +
>> +	if (WARN_ON_ONCE(slab_is_available())) {
>> +		if (nid == MAX_NUMNODES)
>> +			return kzalloc(size, GFP_NOWAIT);
>> +		else
>> +			return kzalloc_node(size, GFP_NOWAIT, nid);
>> +	}
> 
> The use of MAX_NUMNODES is a bit unconventional here.  I *think* we
> generally use NUMA_NO_NODE to indicate "don't care".  I Also *think*
> that if this code did s/MAX_NUMNODES/NUMA_NO_NODE/g then the above
> simply becomes
> 
> 	return kzalloc_node(size, GFP_NOWAIT, nid);
> 
> and kzalloc_node() handles NUMA_NO_NODE appropriately.
> 
> I *think* ;)  Please check all this.
> 
I guess same comment was given by Tejun as well. We didn't
address that in this series mainly because when NO_BOOTMEM
are not enabled, all calls of the new APIs will
be redirected to bootmem  where MAX_NUMNODES is used.

Also, memblock core APIs __next_free_mem_range_rev() and
__next_free_mem_range() would need to be updated, and as result
we will need to re-check/update all direct calls of
memblock_alloc_xxx() APIs (including nobootmem).

So to keep behavior consistent with and without NO_BOOTMEM, we
used MAX_NUMNODES. Once we get a stage where we can remove
the bootmem.c, it should be easy to update the code
to use NUMA_NO_NODE without too much churn.

Regards,
Santosh
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/