Messages in this thread | | | Date | Mon, 19 Dec 2011 11:29:36 -0800 (PST) | From | David Rientjes <> | Subject | Re: [PATCH] mm: Fix BUILD_BUG assertion in pmdp_clear_flush_young() |
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On Mon, 19 Dec 2011, David Daney wrote:
> From: David Daney <david.daney@cavium.com> > > It has been reported that when building for sh: > > mm/pgtable-generic.c: In function 'pmdp_clear_flush_young': > mm/pgtable-generic.c:76: error: call to '__build_bug_failed' declared with attribute error: BUILD_BUG failed > > Adding some ugle #ifdeffery will probably fix this issue. >
It won't, CONFIG_HUGETLB_PAGE has nothing at all to do with this.
> Signed-off-by: David Daney <david.daney@cavium.com> > --- > > This is completely untested, but may be the best fix for this. Linus > and others have expressed a dislike for using BUG() to detect what > should be dead code paths at runtime, but it seems to be the state of > the art here. >
The problem here is that HPAGE_PMD_MASK is being referenced without CONFIG_TRANSPARENT_HUGEPAGE. pmdp_clear_flush_young() is only applicable with that config option enabled. So rather than trying to minimize lines captured under an #ifdef by placing the BUG() directly in the function for asm-generic, you'll need to wrap pmd_clear_flush_young() with #ifdef CONFIG_TRANSPARENT_HUGEPAGE and define its equivalent for CONFIG_TRANSPARENT_HUGEPAGE=n that breaks the build if not enabled.
> mm/pgtable-generic.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/mm/pgtable-generic.c b/mm/pgtable-generic.c > index eb663fb..73784c8 100644 > --- a/mm/pgtable-generic.c > +++ b/mm/pgtable-generic.c > @@ -70,7 +70,7 @@ int pmdp_clear_flush_young(struct vm_area_struct *vma, > unsigned long address, pmd_t *pmdp) > { > int young; > -#ifndef CONFIG_TRANSPARENT_HUGEPAGE > +#if !defined(CONFIG_HUGETLB_PAGE) || !defined(CONFIG_TRANSPARENT_HUGEPAGE) > BUG(); > #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ > VM_BUG_ON(address & ~HPAGE_PMD_MASK);
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