On Mon, 30 Jan 2017, Michal Hocko wrote:
> From: Michal Hocko <[email protected]> > > copy_params uses kmalloc with vmalloc fallback. We already have a helper > for that - kvmalloc. This caller requires GFP_NOIO semantic so it hasn't > been converted with many others by previous patches. All we need to > achieve this semantic is to use the scope memalloc_noio_{save,restore} > around kvmalloc. > > Cc: Mikulas Patocka <[email protected]> > Cc: Mike Snitzer <[email protected]> > Signed-off-by: Michal Hocko <[email protected]> > --- > drivers/md/dm-ioctl.c | 13 ++++--------- > 1 file changed, 4 insertions(+), 9 deletions(-) > > diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c > index a5a9b17f0f7f..dbf5b981f7d7 100644 > --- a/drivers/md/dm-ioctl.c > +++ b/drivers/md/dm-ioctl.c > @@ -1698,6 +1698,7 @@ static int copy_params(struct dm_ioctl __user *user, > struct dm_ioctl *param_kern > struct dm_ioctl *dmi; > int secure_data; > const size_t minimum_data_size = offsetof(struct dm_ioctl, data); > + unsigned noio_flag; > > if (copy_from_user(param_kernel, user, minimum_data_size)) > return -EFAULT; > @@ -1720,15 +1721,9 @@ static int copy_params(struct dm_ioctl __user *user, > struct dm_ioctl *param_kern > * Use kmalloc() rather than vmalloc() when we can. > */ > dmi = NULL; > - if (param_kernel->data_size <= KMALLOC_MAX_SIZE) > - dmi = kmalloc(param_kernel->data_size, GFP_NOIO | __GFP_NORETRY > | __GFP_NOMEMALLOC | __GFP_NOWARN); > - > - 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); > - } > + noio_flag = memalloc_noio_save(); > + dmi = kvmalloc(param_kernel->data_size, GFP_KERNEL); > + memalloc_noio_restore(noio_flag); > > if (!dmi) { > if (secure_data && clear_user(user, param_kernel->data_size)) > -- > 2.11.0 I would push these memalloc_noio_save/memalloc_noio_restore calls to kvmalloc, so that the othe callers can use them too. Something like if ((flags & (__GFP_IO | __GFP_FS)) != (__GFP_IO | __GFP_FS)) noio_flag = memalloc_noio_save(); ptr = __vmalloc_node_flags(size, node, flags); if ((flags & (__GFP_IO | __GFP_FS)) != (__GFP_IO | __GFP_FS)) memalloc_noio_restore(noio_flag) Or perhaps even better - push memalloc_noio_save/memalloc_noio_restore directly to __vmalloc, so that __vmalloc respects the gfp flags properly - note that there are 14 places in the kernel where __vmalloc is called with GFP_NOFS and they are all buggy because __vmalloc doesn't respect the GFP_NOFS flag. Mikulas
