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hugetlb: restrict hugepage_migration_support() to x86_64

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Currently hugepage migration is available for all archs which support
pmd-level hugepage, but testing is done only for x86_64 and there're
bugs for other archs.  So to avoid breaking such archs, this patch
limits the availability strictly to x86_64 until developers of other
archs get interested in enabling this feature.

Simply disabling hugepage migration on non-x86_64 archs is not enough to
fix the reported problem where sys_move_pages() hits the BUG_ON() in
follow_page(FOLL_GET), so let's fix this by checking if hugepage
migration is supported in vma_migratable().

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Reported-by: Michael Ellerman <mpe@ellerman.id.au>
Tested-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Miller <davem@davemloft.net>
Cc: <stable@vger.kernel.org>	[3.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Naoya Horiguchi 2014-06-04 16:05:35 -07:00 • committed by Linus Torvalds
parent 7f39dda9d8
commit c177c81e09
15 changed files with 18 additions and 73 deletions
Download patch file Download diff file Expand all files Collapse all files

13
include/linux/hugetlb.h
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@ -392,15 +392,13 @@ static inline pgoff_t basepage_index(struct page *page)
extern void dissolve_free_huge_pages(unsigned long start_pfn,
unsigned long end_pfn);
int pmd_huge_support(void);
/*
* Currently hugepage migration is enabled only for pmd-based hugepage.
* This function will be updated when hugepage migration is more widely
* supported.
*/
static inline int hugepage_migration_support(struct hstate *h)
{
return pmd_huge_support() && (huge_page_shift(h) == PMD_SHIFT);
#ifdef CONFIG_ARCH_ENABLE_HUGEPAGE_MIGRATION
return huge_page_shift(h) == PMD_SHIFT;
#else
return 0;
#endif
}
static inline spinlock_t *huge_pte_lockptr(struct hstate *h,
@ -450,7 +448,6 @@ static inline pgoff_t basepage_index(struct page *page)
return page->index;
}
#define dissolve_free_huge_pages(s, e) do {} while (0)
#define pmd_huge_support() 0
#define hugepage_migration_support(h) 0
static inline spinlock_t *huge_pte_lockptr(struct hstate *h,