| Message ID | 1617947717-2424-1-git-send-email-anshuman.khandual@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/page_alloc: Ensure that HUGETLB_PAGE_ORDER is less than MAX_ORDER | expand |
On 09.04.21 07:55, Anshuman Khandual wrote: > pageblock_order must always be less than MAX_ORDER, otherwise it might lead > to an warning during boot. A similar problem got fixed on arm64 platform > with the commit 79cc2ed5a716 ("arm64/mm: Drop THP conditionality from > FORCE_MAX_ZONEORDER"). Assert the above condition before HUGETLB_PAGE_ORDER > gets assigned as pageblock_order. This will help detect the problem earlier > on platforms where HUGETLB_PAGE_SIZE_VARIABLE is enabled. > > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: linux-mm@kvack.org > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> > --- > mm/page_alloc.c | 11 +++++++++-- > 1 file changed, 9 insertions(+), 2 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 604dcd69397b..81b7460e1228 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -7068,10 +7068,17 @@ void __init set_pageblock_order(void) > if (pageblock_order) > return; > > - if (HPAGE_SHIFT > PAGE_SHIFT) > + if (HPAGE_SHIFT > PAGE_SHIFT) { > + /* > + * pageblock_order must always be less than > + * MAX_ORDER. So does HUGETLB_PAGE_ORDER if > + * that is being assigned here. > + */ > + WARN_ON(HUGETLB_PAGE_ORDER >= MAX_ORDER); Can't that be a BUILD_BUG_ON() ? > order = HUGETLB_PAGE_ORDER; > - else > + } else { > order = MAX_ORDER - 1; > + } > > /* > * Assume the largest contiguous order of interest is a huge page. >
On 4/9/21 1:54 PM, David Hildenbrand wrote: > On 09.04.21 07:55, Anshuman Khandual wrote: >> pageblock_order must always be less than MAX_ORDER, otherwise it might lead >> to an warning during boot. A similar problem got fixed on arm64 platform >> with the commit 79cc2ed5a716 ("arm64/mm: Drop THP conditionality from >> FORCE_MAX_ZONEORDER"). Assert the above condition before HUGETLB_PAGE_ORDER >> gets assigned as pageblock_order. This will help detect the problem earlier >> on platforms where HUGETLB_PAGE_SIZE_VARIABLE is enabled. >> >> Cc: Andrew Morton <akpm@linux-foundation.org> >> Cc: linux-mm@kvack.org >> Cc: linux-kernel@vger.kernel.org >> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> >> --- >> mm/page_alloc.c | 11 +++++++++-- >> 1 file changed, 9 insertions(+), 2 deletions(-) >> >> diff --git a/mm/page_alloc.c b/mm/page_alloc.c >> index 604dcd69397b..81b7460e1228 100644 >> --- a/mm/page_alloc.c >> +++ b/mm/page_alloc.c >> @@ -7068,10 +7068,17 @@ void __init set_pageblock_order(void) >> if (pageblock_order) >> return; >> - if (HPAGE_SHIFT > PAGE_SHIFT) >> + if (HPAGE_SHIFT > PAGE_SHIFT) { >> + /* >> + * pageblock_order must always be less than >> + * MAX_ORDER. So does HUGETLB_PAGE_ORDER if >> + * that is being assigned here. >> + */ >> + WARN_ON(HUGETLB_PAGE_ORDER >= MAX_ORDER); > > Can't that be a BUILD_BUG_ON() ? Yes, it can be. Probably might be appropriate as well, given that both the arguments here are compile time constants. Okay, will change. > >> order = HUGETLB_PAGE_ORDER; >> - else >> + } else { >> order = MAX_ORDER - 1; >> + } >> /* >> * Assume the largest contiguous order of interest is a huge page. >> > >
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 604dcd69397b..81b7460e1228 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7068,10 +7068,17 @@ void __init set_pageblock_order(void) if (pageblock_order) return; - if (HPAGE_SHIFT > PAGE_SHIFT) + if (HPAGE_SHIFT > PAGE_SHIFT) { + /* + * pageblock_order must always be less than + * MAX_ORDER. So does HUGETLB_PAGE_ORDER if + * that is being assigned here. + */ + WARN_ON(HUGETLB_PAGE_ORDER >= MAX_ORDER); order = HUGETLB_PAGE_ORDER; - else + } else { order = MAX_ORDER - 1; + } /* * Assume the largest contiguous order of interest is a huge page.
pageblock_order must always be less than MAX_ORDER, otherwise it might lead to an warning during boot. A similar problem got fixed on arm64 platform with the commit 79cc2ed5a716 ("arm64/mm: Drop THP conditionality from FORCE_MAX_ZONEORDER"). Assert the above condition before HUGETLB_PAGE_ORDER gets assigned as pageblock_order. This will help detect the problem earlier on platforms where HUGETLB_PAGE_SIZE_VARIABLE is enabled. Cc: Andrew Morton <akpm@linux-foundation.org> Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com> --- mm/page_alloc.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)