| Message ID | 161058501210.1840162.8108917599181157327.stgit@dwillia2-desk3.amr.corp.intel.com |
|---|---|
| State | Accepted |
| Commit | dad4e5b390866ca902653df0daa864ae4b8d4147 |
| Headers | show |
| Series | mm: Fix pfn_to_online_page() with respect to ZONE_DEVICE | expand |
On Wed, 13 Jan 2021 16:43:32 -0800 Dan Williams <dan.j.williams@intel.com> wrote: > 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. > > Fixes: feec24a6139d ("mm, soft-offline: convert parameter to pfn") > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Naoya Horiguchi <nao.horiguchi@gmail.com> > Cc: Michal Hocko <mhocko@kernel.org> > Reviewed-by: David Hildenbrand <david@redhat.com> > Reviewed-by: Oscar Salvador <osalvador@suse.de> > Cc: <stable@vger.kernel.org> > Signed-off-by: Dan Williams <dan.j.williams@intel.com> A cc:stable patch in the middle is awkward. I'll make this a standalone patch for merging into mainline soon (for 5.11) and shall turn the rest into a 4-patch series, OK?
On Sun, Jan 17, 2021 at 2:01 PM Andrew Morton <akpm@linux-foundation.org> wrote: > > On Wed, 13 Jan 2021 16:43:32 -0800 Dan Williams <dan.j.williams@intel.com> wrote: > > > 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. > > > > Fixes: feec24a6139d ("mm, soft-offline: convert parameter to pfn") > > Cc: Andrew Morton <akpm@linux-foundation.org> > > Cc: Naoya Horiguchi <nao.horiguchi@gmail.com> > > Cc: Michal Hocko <mhocko@kernel.org> > > Reviewed-by: David Hildenbrand <david@redhat.com> > > Reviewed-by: Oscar Salvador <osalvador@suse.de> > > Cc: <stable@vger.kernel.org> > > Signed-off-by: Dan Williams <dan.j.williams@intel.com> > > A cc:stable patch in the middle is awkward. I'll make this a > standalone patch for merging into mainline soon (for 5.11) and shall > turn the rest into a 4-patch series, OK? Sounds good to me.
diff --git a/mm/memory-failure.c b/mm/memory-failure.c index 5a38e9eade94..78b173c7190c 100644 --- a/mm/memory-failure.c +++ b/mm/memory-failure.c @@ -1885,6 +1885,12 @@ static int soft_offline_free_page(struct page *page) 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 page *page) 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; }
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. Fixes: feec24a6139d ("mm, soft-offline: convert parameter to pfn") Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Naoya Horiguchi <nao.horiguchi@gmail.com> Cc: Michal Hocko <mhocko@kernel.org> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: <stable@vger.kernel.org> Signed-off-by: Dan Williams <dan.j.williams@intel.com> --- mm/memory-failure.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-)