[dpdk-stable] [PATCH 0/3] eal: clean up mapping hugepages in secondary process for ppc64le

[Gowrishankar]

From: Gowrishankar Muthukrishnan <gowrishankar.m at linux.vnet.ibm.com>

Earlier powerpc arch encountered an issue in secondary process
to map hugepages in same VA range as mapped by primary process.
By then, proposed fix was to use nr_overcommit_hugepages from 
the kernel and mmap using MAP_HUGETLB|MAP_ANONYMOUS flags. Though
it solved respecting address hints in mmap calls, this fix
introduced limitation of maximum VA space that, primary process
in DPDK can create upon hugepages, to physical RAM size (almost).

This patch cleans up this limitation by

 1. reverting the previous patch so that, virtual address space
    range is not a constraint (like other arch).
        
 2. reverse-indexing on hugepage files as the secondary
    process mmap them. Reversed addressing sequence makes 
    this mandate.
    
 3. Move slightly where munmap() is called in zero-mapped VA
    block, as secondary process would attach them.
    
All these changes has also been verified in x86 arch (and request
other arch maintainers too test this and give feedback).

Fixes: 284ae3e9ff ("eal/ppc: fix mmap for memory initialization")
Cc: stable at dpdk.org

Signed-off-by: Gowrishankar Muthukrishnan <gowrishankar.m at linux.vnet.ibm.com>


IBM Internal:
=============
Refer to below bug to understand powerpc memory slice op:
 * https://bugzilla.linux.ibm.com/show_bug.cgi?id=141628#c2

This patch overcomes multiples issues we have been facing until 
now:

 * EAL: Cannot get a virtual area: Cannot allocate memory - warning misleading end users.
 * Multiple memsegs leading heap corruption for rte_malloc (https://dpdk.org/ml/archives/dev/2018-May/100085.html)
 * Bug 166908 - net/mlx5: RXQ allocation failure when sysfs vm.nr_overcommit_hugepages enabled
 * Bug 166960 - lpm: memory allocation failed as applications start when nr_overcommit_hugepages set

I am doing more validations on the patches, as I see initial tests pass from these known issues.

 * http://pastebin.hursley.ibm.com/12493

Gowrishankar Muthukrishnan (3):
  eal: access hugepage_file in reverse order for powerpc
  eal: reorder calling munmap on zero-mapped memory
  eal: reverse powerpc changes done for hugepage overcommit

 doc/guides/linux_gsg/sys_reqs.rst        |  6 ------
 lib/librte_eal/linuxapp/eal/eal_memory.c | 22 +++++++++-------------
 2 files changed, 9 insertions(+), 19 deletions(-)

-- 
1.9.1