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Message-ID: <20150706134750.GA31600@redhat.com>
Date: Mon, 6 Jul 2015 09:47:50 -0400
From: Mike Snitzer <snitzer@...hat.com>
To: Mikulas Patocka <mpatocka@...hat.com>
Cc: "Alasdair G. Kergon" <agk@...hat.com>,
Edward Thornber <thornber@...hat.com>, dm-devel@...hat.com,
David Rientjes <rientjes@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 4/7] dm: introduce dm_kvmalloc
On Fri, Jul 03 2015 at 4:59pm -0400,
Mikulas Patocka <mpatocka@...hat.com> wrote:
> Introduce the functions dm_kvmalloc and dm_kvmalloc_node. These functions
> attempt to do allocation with kmalloc and if it fails, use vmalloc. Memory
> allocated with these functions should be freed with kvfree (that function
> is already present in the Linux kernel).
>
> Signed-off-by: Mikulas Patocka <mpatocka@...hat.com>
>
> ---
> drivers/md/dm-ioctl.c | 26 +++++---------------------
> drivers/md/dm-table.c | 37 +++++++++++++++++++++++++++++++++++++
> include/linux/device-mapper.h | 2 ++
> 3 files changed, 44 insertions(+), 21 deletions(-)
>
> Index: linux-4.1/drivers/md/dm-ioctl.c
> ===================================================================
> --- linux-4.1.orig/drivers/md/dm-ioctl.c 2015-07-02 19:21:15.000000000 +0200
> +++ linux-4.1/drivers/md/dm-ioctl.c 2015-07-02 19:21:21.000000000 +0200
> @@ -1676,12 +1676,8 @@ static void free_params(struct dm_ioctl
> if (param_flags & DM_WIPE_BUFFER)
> memset(param, 0, param_size);
>
> - if (param_flags & DM_PARAMS_ALLOC) {
> - if (is_vmalloc_addr(param))
> - vfree(param);
> - else
> - kfree(param);
> - }
> + if (param_flags & DM_PARAMS_ALLOC)
> + kvfree(param);
> }
>
> static int copy_params(struct dm_ioctl __user *user, struct dm_ioctl *param_kernel,
> @@ -1712,21 +1708,7 @@ static int copy_params(struct dm_ioctl _
> * Try to avoid low memory issues when a device is suspended.
> * 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)
> - *param_flags |= DM_PARAMS_ALLOC;
> - }
> -
> - if (!dmi) {
> - unsigned noio_flag;
> - noio_flag = memalloc_noio_save();
> - dmi = __vmalloc(param_kernel->data_size, GFP_NOIO | __GFP_REPEAT | __GFP_HIGH | __GFP_HIGHMEM, PAGE_KERNEL);
> - memalloc_noio_restore(noio_flag);
> - if (dmi)
> - *param_flags |= DM_PARAMS_ALLOC;
> - }
> + dmi = dm_kvmalloc(param_kernel->data_size, GFP_NOIO);
>
> if (!dmi) {
> if (secure_data && clear_user(user, param_kernel->data_size))
> @@ -1734,6 +1716,8 @@ static int copy_params(struct dm_ioctl _
> return -ENOMEM;
> }
>
> + *param_flags |= DM_PARAMS_ALLOC;
> +
> if (copy_from_user(dmi, user, param_kernel->data_size))
> goto bad;
>
> Index: linux-4.1/include/linux/device-mapper.h
> ===================================================================
> --- linux-4.1.orig/include/linux/device-mapper.h 2015-07-02 19:21:16.000000000 +0200
> +++ linux-4.1/include/linux/device-mapper.h 2015-07-02 19:21:21.000000000 +0200
> @@ -475,6 +475,8 @@ struct dm_table *dm_swap_table(struct ma
> /*
> * A wrapper around vmalloc.
> */
> +void *dm_kvmalloc_node(size_t size, gfp_t gfp, int node);
> +void *dm_kvmalloc(size_t size, gfp_t gfp);
> void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size);
>
> /*-----------------------------------------------------------------
> Index: linux-4.1/drivers/md/dm-table.c
> ===================================================================
> --- linux-4.1.orig/drivers/md/dm-table.c 2015-07-02 19:21:16.000000000 +0200
> +++ linux-4.1/drivers/md/dm-table.c 2015-07-02 19:28:18.000000000 +0200
> @@ -131,6 +131,43 @@ static int setup_btree_index(unsigned in
> return 0;
> }
>
> +void *dm_kvmalloc_node(size_t size, gfp_t gfp, int node)
> +{
> + void *p;
> + unsigned uninitialized_var(noio_flag);
> +
> + /* vmalloc doesn't support no-wait allocations */
> + WARN_ON(!(gfp & __GFP_WAIT));
> +
> + if (likely(size <= KMALLOC_MAX_SIZE)) {
> + p = kmalloc_node(size, gfp | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN, node);
> + if (likely(p != NULL))
> + return p;
> + }
> + if ((gfp & (__GFP_IO | __GFP_FS)) != (__GFP_IO | __GFP_FS)) {
> + /*
> + * vmalloc allocates page tables with GFP_KERNEL, regardless
> + * of GFP flags passed to it. If we are no GFP_NOIO context,
> + * we call memalloc_noio_save, so that all allocations are
> + * implicitly done with GFP_NOIO.
> + */
> + noio_flag = memalloc_noio_save();
> + gfp |= __GFP_HIGH;
> + }
> + p = __vmalloc_node_flags(size, node, gfp | __GFP_REPEAT | __GFP_HIGHMEM);
> + if ((gfp & (__GFP_IO | __GFP_FS)) != (__GFP_IO | __GFP_FS)) {
> + memalloc_noio_restore(noio_flag);
> + }
> + return p;
> +}
> +EXPORT_SYMBOL(dm_kvmalloc_node);
> +
> +void *dm_kvmalloc(size_t size, gfp_t gfp)
> +{
> + return dm_kvmalloc_node(size, gfp, NUMA_NO_NODE);
> +}
> +EXPORT_SYMBOL(dm_kvmalloc);
> +
> void *dm_vcalloc(unsigned long nmemb, unsigned long elem_size)
> {
> unsigned long size;
>
In general I like what you've done with this patchset _except_ I'm not
seeing why dm_kvmalloc() should be in DM at all. It should probably be
elevated to an kvmalloc() export from mm/util.c and include/linux/mm.h
along-side kvfree().
David and/or Andrew, what do you think?
FYI, full patchset starts here:
https://www.redhat.com/archives/dm-devel/2015-July/msg00004.html
(but Mikulas didn't chain the reply so the 7 patches aren't properly
threaded/navigated, you can dig out the patches toward the top of the
list here: https://patchwork.kernel.org/project/dm-devel/list/ )
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