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Date: Wed, 8 Mar 2017 08:33:58 +0100
From: Vlastimil Babka <vbabka@...e.cz>
To: Michal Hocko <mhocko@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>
Cc: Al Viro <viro@...iv.linux.org.uk>,
David Rientjes <rientjes@...gle.com>,
Cristopher Lameter <cl@...ux.com>, linux-mm@...ck.org,
LKML <linux-kernel@...r.kernel.org>,
Michal Hocko <mhocko@...e.com>
Subject: Re: [PATCH] mm, vmalloc: use __GFP_HIGHMEM implicitly
On 03/07/2017 03:10 PM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@...e.com>
>
> __vmalloc* allows users to provide gfp flags for the underlying
> allocation. This API is quite popular
> $ git grep "=[[:space:]]__vmalloc\|return[[:space:]]*__vmalloc" | wc -l
> 77
>
> the only problem is that many people are not aware that they really want
> to give __GFP_HIGHMEM along with other flags because there is really no
> reason to consume precious lowmemory on CONFIG_HIGHMEM systems for pages
> which are mapped to the kernel vmalloc space. About half of users don't
> use this flag, though. This signals that we make the API unnecessarily
> too complex.
>
> This patch simply uses __GFP_HIGHMEM implicitly when allocating pages to
> be mapped to the vmalloc space. Current users which add __GFP_HIGHMEM
> are simplified and drop the flag.
>
> Signed-off-by: Michal Hocko <mhocko@...e.com>
> ---
>
> Hi,
> this has been posted [1] as an RFC before and nobody really screamed
> about this. Well, there was only little feedback, to be honest. I still
> believe this is an improvement and the implicit __GFP_HIGHMEM will make
> the __vmalloc* usage less error prone.
>
> [1] http://lkml.kernel.org/r/20170201140530.1325-1-mhocko@kernel.org
>
> arch/parisc/kernel/module.c | 2 +-
> arch/x86/kernel/module.c | 2 +-
> drivers/block/drbd/drbd_bitmap.c | 2 +-
> drivers/gpu/drm/etnaviv/etnaviv_dump.c | 4 ++--
> drivers/md/dm-bufio.c | 2 +-
> fs/btrfs/free-space-tree.c | 3 +--
> fs/file.c | 2 +-
> fs/xfs/kmem.c | 2 +-
> include/drm/drm_mem_util.h | 9 +++------
> kernel/bpf/core.c | 9 +++------
> kernel/bpf/syscall.c | 3 +--
> kernel/fork.c | 2 +-
> kernel/groups.c | 2 +-
> kernel/module.c | 2 +-
> mm/kasan/kasan.c | 2 +-
> mm/nommu.c | 3 +--
> mm/util.c | 2 +-
> mm/vmalloc.c | 14 +++++++-------
> net/ceph/ceph_common.c | 2 +-
> net/netfilter/x_tables.c | 3 +--
> 20 files changed, 31 insertions(+), 41 deletions(-)
>
> diff --git a/arch/parisc/kernel/module.c b/arch/parisc/kernel/module.c
> index a0ecdb4abcc8..3d4f5660a2e0 100644
> --- a/arch/parisc/kernel/module.c
> +++ b/arch/parisc/kernel/module.c
> @@ -218,7 +218,7 @@ void *module_alloc(unsigned long size)
> * easier than trying to map the text, data, init_text and
> * init_data correctly */
> return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END,
> - GFP_KERNEL | __GFP_HIGHMEM,
> + GFP_KERNEL,
> PAGE_KERNEL_RWX, 0, NUMA_NO_NODE,
> __builtin_return_address(0));
> }
> diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
> index 477ae806c2fa..f67bd3205df7 100644
> --- a/arch/x86/kernel/module.c
> +++ b/arch/x86/kernel/module.c
> @@ -85,7 +85,7 @@ void *module_alloc(unsigned long size)
>
> p = __vmalloc_node_range(size, MODULE_ALIGN,
> MODULES_VADDR + get_module_load_offset(),
> - MODULES_END, GFP_KERNEL | __GFP_HIGHMEM,
> + MODULES_END, GFP_KERNEL,
> PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
> __builtin_return_address(0));
> if (p && (kasan_module_alloc(p, size) < 0)) {
> diff --git a/drivers/block/drbd/drbd_bitmap.c b/drivers/block/drbd/drbd_bitmap.c
> index dece26f119d4..a804a4107fbc 100644
> --- a/drivers/block/drbd/drbd_bitmap.c
> +++ b/drivers/block/drbd/drbd_bitmap.c
> @@ -409,7 +409,7 @@ static struct page **bm_realloc_pages(struct drbd_bitmap *b, unsigned long want)
> new_pages = kzalloc(bytes, GFP_NOIO | __GFP_NOWARN);
> if (!new_pages) {
> new_pages = __vmalloc(bytes,
> - GFP_NOIO | __GFP_HIGHMEM | __GFP_ZERO,
> + GFP_NOIO | __GFP_ZERO,
This should be converted to memalloc_noio_save(), right? And then
kvmalloc? Unless that happens in your other series :)
> PAGE_KERNEL);
> if (!new_pages)
> return NULL;
> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_dump.c b/drivers/gpu/drm/etnaviv/etnaviv_dump.c
> index d019b5e311cc..2d955d7d7b6d 100644
> --- a/drivers/gpu/drm/etnaviv/etnaviv_dump.c
> +++ b/drivers/gpu/drm/etnaviv/etnaviv_dump.c
> @@ -161,8 +161,8 @@ void etnaviv_core_dump(struct etnaviv_gpu *gpu)
> file_size += sizeof(*iter.hdr) * n_obj;
>
> /* Allocate the file in vmalloc memory, it's likely to be big */
> - iter.start = __vmalloc(file_size, GFP_KERNEL | __GFP_HIGHMEM |
> - __GFP_NOWARN | __GFP_NORETRY, PAGE_KERNEL);
> + iter.start = __vmalloc(file_size, GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY,
> + PAGE_KERNEL);
> if (!iter.start) {
> dev_warn(gpu->dev, "failed to allocate devcoredump file\n");
> return;
> diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
> index df4859f6ac6a..c058ae86f51b 100644
> --- a/drivers/md/dm-bufio.c
> +++ b/drivers/md/dm-bufio.c
> @@ -404,7 +404,7 @@ static void *alloc_buffer_data(struct dm_bufio_client *c, gfp_t gfp_mask,
> if (gfp_mask & __GFP_NORETRY)
> noio_flag = memalloc_noio_save();
>
> - ptr = __vmalloc(c->block_size, gfp_mask | __GFP_HIGHMEM, PAGE_KERNEL);
> + ptr = __vmalloc(c->block_size, gfp_mask, PAGE_KERNEL);
>
> if (gfp_mask & __GFP_NORETRY)
> memalloc_noio_restore(noio_flag);
> diff --git a/fs/btrfs/free-space-tree.c b/fs/btrfs/free-space-tree.c
> index dd7fb22a955a..fc0bd8406758 100644
> --- a/fs/btrfs/free-space-tree.c
> +++ b/fs/btrfs/free-space-tree.c
> @@ -167,8 +167,7 @@ static u8 *alloc_bitmap(u32 bitmap_size)
> if (mem)
> return mem;
>
> - return __vmalloc(bitmap_size, GFP_NOFS | __GFP_HIGHMEM | __GFP_ZERO,
> - PAGE_KERNEL);
> + return __vmalloc(bitmap_size, GFP_NOFS | __GFP_ZERO, PAGE_KERNEL);
memalloc_nofs_save() and plain vzalloc()?
> }
>
> int convert_free_space_to_bitmaps(struct btrfs_trans_handle *trans,
[...]
> --- a/mm/kasan/kasan.c
> +++ b/mm/kasan/kasan.c
> @@ -693,7 +693,7 @@ int kasan_module_alloc(void *addr, size_t size)
>
> ret = __vmalloc_node_range(shadow_size, 1, shadow_start,
> shadow_start + shadow_size,
> - GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
> + GFP_KERNEL | __GFP_ZERO,
> PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE,
> __builtin_return_address(0));
>
> diff --git a/mm/nommu.c b/mm/nommu.c
> index a80411d258fc..fc184f597d59 100644
> --- a/mm/nommu.c
> +++ b/mm/nommu.c
> @@ -246,8 +246,7 @@ void *vmalloc_user(unsigned long size)
> {
> void *ret;
>
> - ret = __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
> - PAGE_KERNEL);
> + ret = __vmalloc(size, GFP_KERNEL | __GFP_ZERO, PAGE_KERNEL);
vzalloc()?
> if (ret) {
> struct vm_area_struct *vma;
>
> diff --git a/mm/util.c b/mm/util.c
> index 6ed3e49bf1e5..e5b0623df89d 100644
> --- a/mm/util.c
> +++ b/mm/util.c
> @@ -382,7 +382,7 @@ void *kvmalloc_node(size_t size, gfp_t flags, int node)
> if (ret || size <= PAGE_SIZE)
> return ret;
>
> - return __vmalloc_node_flags(size, node, flags | __GFP_HIGHMEM);
> + return __vmalloc_node_flags(size, node, flags);
> }
> EXPORT_SYMBOL(kvmalloc_node);
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 32979d945766..9fa9274d8f6d 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -1619,7 +1619,7 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
> struct page **pages;
> unsigned int nr_pages, array_size, i;
> const gfp_t nested_gfp = (gfp_mask & GFP_RECLAIM_MASK) | __GFP_ZERO;
> - const gfp_t alloc_mask = gfp_mask | __GFP_NOWARN;
> + const gfp_t alloc_mask = gfp_mask | __GFP_HIGHMEM | __GFP_NOWARN;
>
> nr_pages = get_vm_area_size(area) >> PAGE_SHIFT;
> array_size = (nr_pages * sizeof(struct page *));
> @@ -1788,7 +1788,7 @@ void *__vmalloc_node_flags(unsigned long size,
> void *vmalloc(unsigned long size)
> {
> return __vmalloc_node_flags(size, NUMA_NO_NODE,
> - GFP_KERNEL | __GFP_HIGHMEM);
> + GFP_KERNEL);
Nit: this could now fit on single line.
> }
> EXPORT_SYMBOL(vmalloc);
>
> @@ -1805,7 +1805,7 @@ EXPORT_SYMBOL(vmalloc);
> void *vzalloc(unsigned long size)
> {
> return __vmalloc_node_flags(size, NUMA_NO_NODE,
> - GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO);
> + GFP_KERNEL | __GFP_ZERO);
> }
> EXPORT_SYMBOL(vzalloc);
>
> @@ -1822,7 +1822,7 @@ void *vmalloc_user(unsigned long size)
> void *ret;
>
> ret = __vmalloc_node(size, SHMLBA,
> - GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO,
> + GFP_KERNEL | __GFP_ZERO,
> PAGE_KERNEL, NUMA_NO_NODE,
> __builtin_return_address(0));
> if (ret) {
> @@ -1846,7 +1846,7 @@ EXPORT_SYMBOL(vmalloc_user);
> */
> void *vmalloc_node(unsigned long size, int node)
> {
> - return __vmalloc_node(size, 1, GFP_KERNEL | __GFP_HIGHMEM, PAGE_KERNEL,
> + return __vmalloc_node(size, 1, GFP_KERNEL, PAGE_KERNEL,
> node, __builtin_return_address(0));
> }
> EXPORT_SYMBOL(vmalloc_node);
> @@ -1866,7 +1866,7 @@ EXPORT_SYMBOL(vmalloc_node);
> void *vzalloc_node(unsigned long size, int node)
> {
> return __vmalloc_node_flags(size, node,
> - GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO);
> + GFP_KERNEL | __GFP_ZERO);
This too.
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