[PATCH v3 0/4] mm: fix the "counter.sh" failure for libhugetlbfs

[Huang Shijie <shijie.huang@arm.com>]

(1) Background
   For the arm64, the hugetlb page size can be 32M (PMD + Contiguous bit).
   In the 4K page environment, the max page order is 10 (max_order - 1),
   so 32M page is the gigantic page.    

   The arm64 MMU supports a Contiguous bit which is a hint that the TTE
   is one of a set of contiguous entries which can be cached in a single
   TLB entry.  Please refer to the arm64v8 mannul :
       DDI0487A_f_armv8_arm.pdf (in page D4-1811)

(2) The bug   
   After I tested the libhugetlbfs, I found the test case "counter.sh"
   will fail with the gigantic page (32M page in arm64 board).

   The counter.sh is just a wrapper for counter.c.
   You can find them in:
       https://github.com/libhugetlbfs/libhugetlbfs/blob/master/tests/counters.c
       https://github.com/libhugetlbfs/libhugetlbfs/blob/master/tests/counters.sh

   The error log shows below:

   ----------------------------------------------------------
        ...........................................
	LD_PRELOAD=libhugetlbfs.so shmoverride_unlinked (32M: 64):	PASS
	LD_PRELOAD=libhugetlbfs.so HUGETLB_SHM=yes shmoverride_unlinked (32M: 64):	PASS
	quota.sh (32M: 64):	PASS
	counters.sh (32M: 64):	FAIL mmap failed: Invalid argument
	********** TEST SUMMARY
	*                      32M           
	*                      32-bit 64-bit 
	*     Total testcases:     0     87   
	*             Skipped:     0      0   
	*                PASS:     0     86   
	*                FAIL:     0      1   
	*    Killed by signal:     0      0   
	*   Bad configuration:     0      0   
	*       Expected FAIL:     0      0   
	*     Unexpected PASS:     0      0   
	* Strange test result:     0      0   
	**********
   ----------------------------------------------------------

   The failure is caused by:
    1) kernel fails to allocate a gigantic page for the surplus case.
       And the gather_surplus_pages() will return NULL in the end.

    2) The condition checks for some functions are wrong:
        return_unused_surplus_pages()
        nr_overcommit_hugepages_store()
        hugetlb_overcommit_handler()
   
   This patch set adds support for gigantic surplus hugetlb pages,
   allowing the counter.sh unit test to pass. 
   Test this patch set with Juno-r1 board.

   	
v2 -- > v3:
   1.) In patch 2, change argument "no_init" to "do_prep" 
   2.) In patch 3, also change alloc_fresh_huge_page().
       In the v2, this patch only changes the alloc_fresh_gigantic_page().  
   3.) Merge old patch #4,#5 into the last one.    
   4.) Follow Babka's suggestion, do the NULL check for @mask.
   5.) others.


v1 -- > v2:
   1.) fix the compiler error in X86.
   2.) add new patches for NUMA.
       The patch #2 ~ #5 are new patches.

Huang Shijie (4):
  mm: hugetlb: rename some allocation functions
  mm: hugetlb: add a new parameter for some functions
  mm: hugetlb: change the return type for some functions
  mm: hugetlb: support gigantic surplus pages

 include/linux/mempolicy.h |   8 +++
 mm/hugetlb.c              | 146 +++++++++++++++++++++++++++++++++++-----------
 mm/mempolicy.c            |  44 ++++++++++++++
 3 files changed, 163 insertions(+), 35 deletions(-)

-- 
2.5.5

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