Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753160AbcD1N0G (ORCPT ); Thu, 28 Apr 2016 09:26:06 -0400 Received: from mail-wm0-f43.google.com ([74.125.82.43]:37903 "EHLO mail-wm0-f43.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752877AbcD1NY1 (ORCPT ); Thu, 28 Apr 2016 09:24:27 -0400 From: Michal Hocko To: Andrew Morton Cc: , LKML , Michal Hocko , Shaohua Li , Mikulas Patocka , dm-devel@redhat.com Subject: [PATCH 18/20] dm: clean up GFP_NIO usage Date: Thu, 28 Apr 2016 15:24:04 +0200 Message-Id: <1461849846-27209-19-git-send-email-mhocko@kernel.org> X-Mailer: git-send-email 2.8.0.rc3 In-Reply-To: <1461849846-27209-1-git-send-email-mhocko@kernel.org> References: <1461849846-27209-1-git-send-email-mhocko@kernel.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2980 Lines: 77 From: Michal Hocko copy_params uses GFP_NOIO for explicit allocation requests because this might be called from the suspend path. To quote Mikulas: : The LVM tool calls suspend and resume ioctls on device mapper block : devices. : : When a device is suspended, any bio sent to the device is held. If the : resume ioctl did GFP_KERNEL allocation, the allocation could get stuck : trying to write some dirty cached pages to the suspended device. : : The LVM tool and the dmeventd daemon use mlock to lock its address space, : so the copy_from_user/copy_to_user call cannot trigger a page fault. Relying on the mlock is quite fragile and we have a better way in kernel to enfore NOIO which is already used for the vmalloc fallback. Just use memalloc_noio_{save,restore} around the whole copy_params function which will force the same also to the page fult paths via copy_{from,to}_user. While we are there we can also remove __GFP_NOMEMALLOC because copy_params is never called from MEMALLOC context (e.g. during the reclaim). Cc: Shaohua Li Cc: Mikulas Patocka Cc: dm-devel@redhat.com Signed-off-by: Michal Hocko --- drivers/md/dm-ioctl.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c index 2c7ca258c4e4..fe0b57d7573c 100644 --- a/drivers/md/dm-ioctl.c +++ b/drivers/md/dm-ioctl.c @@ -1715,16 +1715,13 @@ static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kern */ dmi = NULL; if (param_kernel->data_size <= KMALLOC_MAX_SIZE) { - dmi = kmalloc(param_kernel->data_size, GFP_NOIO | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); + dmi = kmalloc(param_kernel->data_size, GFP_KERNEL | __GFP_NORETRY | __GFP_NOWARN); if (dmi) *param_flags |= DM_PARAMS_KMALLOC; } if (!dmi) { - unsigned noio_flag; - noio_flag = memalloc_noio_save(); - dmi = __vmalloc(param_kernel->data_size, GFP_NOIO | __GFP_HIGH | __GFP_HIGHMEM, PAGE_KERNEL); - memalloc_noio_restore(noio_flag); + dmi = __vmalloc(param_kernel->data_size, GFP_KERNEL | __GFP_HIGH | __GFP_HIGHMEM, PAGE_KERNEL); if (dmi) *param_flags |= DM_PARAMS_VMALLOC; } @@ -1801,6 +1798,7 @@ static int ctl_ioctl(uint command, struct dm_ioctl __user *user) ioctl_fn fn = NULL; size_t input_param_size; struct dm_ioctl param_kernel; + unsigned noio_flag; /* only root can play with this */ if (!capable(CAP_SYS_ADMIN)) @@ -1832,9 +1830,12 @@ static int ctl_ioctl(uint command, struct dm_ioctl __user *user) } /* - * Copy the parameters into kernel space. + * Copy the parameters into kernel space. Make sure that no IO is triggered + * from the allocation paths because this might be called during the suspend. */ + noio_flag = memalloc_noio_save(); r = copy_params(user, ¶m_kernel, ioctl_flags, ¶m, ¶m_flags); + memalloc_noio_restore(noio_flag); if (r) return r; -- 2.8.0.rc3