From: Mikulas Patocka <mpatocka@redhat.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Vlastimil Babka <vbabka@suse.cz>,
David Rientjes <rientjes@google.com>,
Mel Gorman <mgorman@suse.de>,
Johannes Weiner <hannes@cmpxchg.org>,
Al Viro <viro@zeniv.linux.org.uk>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
Michal Hocko <mhocko@suse.com>, Mike Snitzer <snitzer@redhat.com>
Subject: Re: [PATCH 7/9] md: use kvmalloc rather than opencoded variant
Date: Wed, 1 Feb 2017 12:29:56 -0500 (EST) [thread overview]
Message-ID: <alpine.LRH.2.02.1702011213070.20806@file01.intranet.prod.int.rdu2.redhat.com> (raw)
In-Reply-To: <20170130094940.13546-8-mhocko@kernel.org>
On Mon, 30 Jan 2017, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> 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 <mpatocka@redhat.com>
> Cc: Mike Snitzer <snitzer@redhat.com>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
> 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
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next prev parent reply other threads:[~2017-02-01 17:30 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-01-30 9:49 [PATCH 0/6 v3] kvmalloc Michal Hocko
2017-01-30 9:49 ` [PATCH 1/9] mm: introduce kv[mz]alloc helpers Michal Hocko
2017-01-30 9:49 ` [PATCH 2/9] mm: support __GFP_REPEAT in kvmalloc_node for >32kB Michal Hocko
2017-01-30 9:49 ` [PATCH 3/9] rhashtable: simplify a strange allocation pattern Michal Hocko
2017-01-30 14:04 ` Vlastimil Babka
2017-01-30 9:49 ` [PATCH 4/9] ila: " Michal Hocko
2017-01-30 15:21 ` Vlastimil Babka
2017-01-30 9:49 ` [PATCH 5/9] treewide: use kv[mz]alloc* rather than opencoded variants Michal Hocko
2017-01-30 10:21 ` Leon Romanovsky
2017-01-30 16:14 ` Vlastimil Babka
2017-01-30 19:24 ` Kees Cook
2017-01-30 9:49 ` [PATCH 6/9] net: use kvmalloc with __GFP_REPEAT rather than open coded variant Michal Hocko
2017-01-30 16:36 ` Vlastimil Babka
2017-01-30 9:49 ` [PATCH 7/9] md: use kvmalloc rather than opencoded variant Michal Hocko
2017-01-30 16:42 ` Vlastimil Babka
2017-02-01 17:29 ` Mikulas Patocka [this message]
2017-02-01 17:58 ` Michal Hocko
2017-01-30 9:49 ` [PATCH 8/9] bcache: use kvmalloc Michal Hocko
2017-01-30 16:47 ` Vlastimil Babka
2017-01-30 17:25 ` Michal Hocko
2017-01-30 9:49 ` [PATCH 9/9] net, bpf: use kvzalloc helper Michal Hocko
2017-01-30 17:20 ` Michal Hocko
2017-02-05 10:23 ` [PATCH 0/6 v3] kvmalloc Michal Hocko
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