mm/hugetlb: introduce hugetlb_bad_size()

When any unsupported hugepage size is specified, 'hugepagesz=' and
'hugepages=' should be ignored during command line parsing until any
supported hugepage size is found.  But currently incorrect number of
hugepages are allocated when unsupported size is specified as it fails
to ignore the 'hugepages=' command.

Test case:

Note that this is specific to x86 architecture.

Boot the kernel with command line option 'hugepagesz=256M hugepages=X'.
After boot, dmesg output shows that X number of hugepages of the size 2M
is pre-allocated instead of 0.

So, to handle such command line options, introduce new routine
hugetlb_bad_size.  The routine hugetlb_bad_size sets the global variable
parsed_valid_hugepagesz.  We are using parsed_valid_hugepagesz to save
the state when unsupported hugepagesize is found so that we can ignore
the 'hugepages=' parameters after that and then reset the variable when
supported hugepage size is found.

The routine hugetlb_bad_size can be called while setting 'hugepagesz='
parameter in an architecture specific code.

Signed-off-by: Vaishali Thakkar <[email protected]>
Reviewed-by: Mike Kravetz <[email protected]>
Reviewed-by: Naoya Horiguchi <[email protected]>
Acked-by: Michal Hocko <[email protected]>
Cc: Hillf Danton <[email protected]>
Cc: Yaowei Bai <[email protected]>
Cc: Dominik Dingel <[email protected]>
Cc: Kirill A. Shutemov <[email protected]>
Cc: Paul Gortmaker <[email protected]>
Cc: Dave Hansen <[email protected]>
Cc: Benjamin Herrenschmidt <[email protected]>
Cc: James Hogan <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: "H. Peter Anvin" <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 7d953c2542a8..e44c57876e89 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -338,6 +338,7 @@ int huge_add_to_page_cache(struct page *page, struct address_space *mapping,
 /* arch callback */
 int __init alloc_bootmem_huge_page(struct hstate *h);
 
+void __init hugetlb_bad_size(void);
 void __init hugetlb_add_hstate(unsigned order);
 struct hstate *size_to_hstate(unsigned long size);