From: Dan Williams dan.j.williams@intel.com Subject: mm: fix page reference leak in soft_offline_page()
The conversion to move pfn_to_online_page() internal to soft_offline_page() missed that the get_user_pages() reference taken by the madvise() path needs to be dropped when pfn_to_online_page() fails. Note the direct sysfs-path to soft_offline_page() does not perform a get_user_pages() lookup.
When soft_offline_page() is handed a pfn_valid() && !pfn_to_online_page() pfn the kernel hangs at dax-device shutdown due to a leaked reference.
Link: https://lkml.kernel.org/r/161058501210.1840162.8108917599181157327.stgit@dwi... Fixes: feec24a6139d ("mm, soft-offline: convert parameter to pfn") Signed-off-by: Dan Williams dan.j.williams@intel.com Reviewed-by: David Hildenbrand david@redhat.com Reviewed-by: Oscar Salvador osalvador@suse.de Reviewed-by: Naoya Horiguchi naoya.horiguchi@nec.com Cc: Michal Hocko mhocko@suse.com Cc: Qian Cai cai@lca.pw Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---
mm/memory-failure.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-)
--- a/mm/memory-failure.c~mm-fix-page-reference-leak-in-soft_offline_page +++ a/mm/memory-failure.c @@ -1885,6 +1885,12 @@ static int soft_offline_free_page(struct return rc; }
+static void put_ref_page(struct page *page) +{ + if (page) + put_page(page); +} + /** * soft_offline_page - Soft offline a page. * @pfn: pfn to soft-offline @@ -1910,20 +1916,26 @@ static int soft_offline_free_page(struct int soft_offline_page(unsigned long pfn, int flags) { int ret; - struct page *page; bool try_again = true; + struct page *page, *ref_page = NULL; + + WARN_ON_ONCE(!pfn_valid(pfn) && (flags & MF_COUNT_INCREASED));
if (!pfn_valid(pfn)) return -ENXIO; + if (flags & MF_COUNT_INCREASED) + ref_page = pfn_to_page(pfn); + /* Only online pages can be soft-offlined (esp., not ZONE_DEVICE). */ page = pfn_to_online_page(pfn); - if (!page) + if (!page) { + put_ref_page(ref_page); return -EIO; + }
if (PageHWPoison(page)) { pr_info("%s: %#lx page already poisoned\n", __func__, pfn); - if (flags & MF_COUNT_INCREASED) - put_page(page); + put_ref_page(ref_page); return 0; }
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