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mm, treewide: redefine MAX_ORDER sanely

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MAX_ORDER currently defined as number of orders page allocator supports:
user can ask buddy allocator for page order between 0 and MAX_ORDER-1.

This definition is counter-intuitive and lead to number of bugs all over
the kernel.

Change the definition of MAX_ORDER to be inclusive: the range of orders
user can ask from buddy allocator is 0..MAX_ORDER now.

[kirill@shutemov.name: fix min() warning]
  Link: https://lkml.kernel.org/r/20230315153800.32wib3n5rickolvh@box
[akpm@linux-foundation.org: fix another min_t warning]
[kirill@shutemov.name: fixups per Zi Yan]
  Link: https://lkml.kernel.org/r/20230316232144.b7ic4cif4kjiabws@box.shutemov.name
[akpm@linux-foundation.org: fix underlining in docs]
  Link: https://lore.kernel.org/oe-kbuild-all/202303191025.VRCTk6mP-lkp@intel.com/
Link: https://lkml.kernel.org/r/20230315113133.11326-11-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Michael Ellerman <mpe@ellerman.id.au>	[powerpc]
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Kirill A. Shutemov
2023-03-15 14:31:33 +03:00
committed by Andrew Morton
parent 61883d3c32
commit 23baf831a3
84 changed files with 223 additions and 253 deletions
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6
Documentation/admin-guide/kdump/vmcoreinfo.rst
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@@ -172,7 +172,7 @@ variables.
Offset of the free_list's member. This value is used to compute the number
of free pages.
Each zone has a free_area structure array called free_area[MAX_ORDER].
Each zone has a free_area structure array called free_area[MAX_ORDER + 1].
The free_list represents a linked list of free page blocks.
(list_head, next|prev)
@@ -189,8 +189,8 @@ Offsets of the vmap_area's members. They carry vmalloc-specific
information. Makedumpfile gets the start address of the vmalloc region
from this.
(zone.free_area, MAX_ORDER)
---------------------------
(zone.free_area, MAX_ORDER + 1)
-------------------------------
Free areas descriptor. User-space tools use this value to iterate the
free_area ranges. MAX_ORDER is used by the zone buddy allocator.