4.13-stable review patch. If anyone has any objections, please let me know.
------------------ From: Alexandru Moise <[email protected]> commit 19bfbe22f59a207417b2679e7e83c180419c9ec5 upstream. This fixes a bug in madvise() where if you'd try to soft offline a hugepage via madvise(), while walking the address range you'd end up, using the wrong page offset due to attempting to get the compound order of a former but presently not compound page, due to dissolving the huge page (since commit c3114a84f7f9: "mm: hugetlb: soft-offline: dissolve source hugepage after successful migration"). As a result I ended up with all my free pages except one being offlined. Link: http://lkml.kernel.org/r/[email protected] Fixes: c3114a84f7f9 ("mm: hugetlb: soft-offline: dissolve source hugepage after successful migration") Signed-off-by: Alexandru Moise <[email protected]> Cc: Anshuman Khandual <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Andrea Arcangeli <[email protected]> Cc: Minchan Kim <[email protected]> Cc: Hillf Danton <[email protected]> Cc: Shaohua Li <[email protected]> Cc: Mike Rapoport <[email protected]> Cc: "Kirill A. Shutemov" <[email protected]> Cc: Mel Gorman <[email protected]> Cc: David Rientjes <[email protected]> Cc: Rik van Riel <[email protected]> Cc: Naoya Horiguchi <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- mm/madvise.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) --- a/mm/madvise.c +++ b/mm/madvise.c @@ -614,18 +614,26 @@ static int madvise_inject_error(int beha { struct page *page; struct zone *zone; + unsigned int order; if (!capable(CAP_SYS_ADMIN)) return -EPERM; - for (; start < end; start += PAGE_SIZE << - compound_order(compound_head(page))) { + + for (; start < end; start += PAGE_SIZE << order) { int ret; ret = get_user_pages_fast(start, 1, 0, &page); if (ret != 1) return ret; + /* + * When soft offlining hugepages, after migrating the page + * we dissolve it, therefore in the second loop "page" will + * no longer be a compound page, and order will be 0. + */ + order = compound_order(compound_head(page)); + if (PageHWPoison(page)) { put_page(page); continue;
