4.16-stable review patch. If anyone has any objections, please let me know.
------------------ From: Michael S. Tsirkin <m...@redhat.com> commit 09e35a4a1ca8b9988ca9b8557d17948cd6c0808b upstream. Patch series "mm/get_user_pages_fast fixes, cleanups", v2. Turns out get_user_pages_fast and __get_user_pages_fast return different values on error when given a single page: __get_user_pages_fast returns 0. get_user_pages_fast returns either 0 or an error. Callers of get_user_pages_fast expect an error so fix it up to return an error consistently. Stress the difference between get_user_pages_fast and __get_user_pages_fast to make sure callers aren't confused. This patch (of 3): __gup_benchmark_ioctl does not handle the case where get_user_pages_fast fails: - a negative return code will cause a buffer overrun - returning with partial success will cause use of uninitialized memory. [a...@linux-foundation.org: simplification] Link: http://lkml.kernel.org/r/1522962072-182137-3-git-send-email-...@redhat.com Signed-off-by: Michael S. Tsirkin <m...@redhat.com> Reviewed-by: Andrew Morton <a...@linux-foundation.org> Cc: Kirill A. Shutemov <kirill.shute...@linux.intel.com> Cc: Huang Ying <ying.hu...@intel.com> Cc: Jonathan Corbet <cor...@lwn.net> Cc: Peter Zijlstra <pet...@infradead.org> Cc: Thomas Gleixner <t...@linutronix.de> Cc: Thorsten Leemhuis <regressi...@leemhuis.info> Cc: <sta...@vger.kernel.org> Signed-off-by: Andrew Morton <a...@linux-foundation.org> Signed-off-by: Linus Torvalds <torva...@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- mm/gup_benchmark.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/mm/gup_benchmark.c +++ b/mm/gup_benchmark.c @@ -23,7 +23,7 @@ static int __gup_benchmark_ioctl(unsigne struct page **pages; nr_pages = gup->size / PAGE_SIZE; - pages = kvmalloc(sizeof(void *) * nr_pages, GFP_KERNEL); + pages = kvzalloc(sizeof(void *) * nr_pages, GFP_KERNEL); if (!pages) return -ENOMEM; @@ -41,6 +41,8 @@ static int __gup_benchmark_ioctl(unsigne } nr = get_user_pages_fast(addr, nr, gup->flags & 1, pages + i); + if (nr <= 0) + break; i += nr; } end_time = ktime_get();
