mm: introduce kv[mz]alloc helpers

Patch series "kvmalloc", v5.

There are many open coded kmalloc with vmalloc fallback instances in the
tree.  Most of them are not careful enough or simply do not care about
the underlying semantic of the kmalloc/page allocator which means that
a) some vmalloc fallbacks are basically unreachable because the kmalloc
part will keep retrying until it succeeds b) the page allocator can
invoke a really disruptive steps like the OOM killer to move forward
which doesn't sound appropriate when we consider that the vmalloc
fallback is available.

As it can be seen implementing kvmalloc requires quite an intimate
knowledge if the page allocator and the memory reclaim internals which
strongly suggests that a helper should be implemented in the memory
subsystem proper.

Most callers, I could find, have been converted to use the helper
instead.  This is patch 6.  There are some more relying on __GFP_REPEAT
in the networking stack which I have converted as well and Eric Dumazet
was not opposed [2] to convert them as well.

[1] http://lkml.kernel.org/r/20170130094940.13546-1-mhocko@kernel.org
[2] http://lkml.kernel.org/r/1485273626.16328.301.camel@edumazet-glaptop3.roam.corp.google.com

This patch (of 9):

Using kmalloc with the vmalloc fallback for larger allocations is a
common pattern in the kernel code.  Yet we do not have any common helper
for that and so users have invented their own helpers.  Some of them are
really creative when doing so.  Let's just add kv[mz]alloc and make sure
it is implemented properly.  This implementation makes sure to not make
a large memory pressure for > PAGE_SZE requests (__GFP_NORETRY) and also
to not warn about allocation failures.  This also rules out the OOM
killer as the vmalloc is a more approapriate fallback than a disruptive
user visible action.

This patch also changes some existing users and removes helpers which
are specific for them.  In some cases this is not possible (e.g.
ext4_kvmalloc, libcfs_kvzalloc) because those seems to be broken and
require GFP_NO{FS,IO} context which is not vmalloc compatible in general
(note that the page table allocation is GFP_KERNEL).  Those need to be
fixed separately.

While we are at it, document that __vmalloc{_node} about unsupported gfp
mask because there seems to be a lot of confusion out there.
kvmalloc_node will warn about GFP_KERNEL incompatible (which are not
superset) flags to catch new abusers.  Existing ones would have to die
slowly.

[sfr@canb.auug.org.au: f2fs fixup]
  Link: http://lkml.kernel.org/r/20170320163735.332e64b7@canb.auug.org.au
Link: http://lkml.kernel.org/r/20170306103032.2540-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Reviewed-by: Andreas Dilger <adilger@dilger.ca>	[ext4 part]
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

5 files changed, 3 insertions, 44 deletions

diff --git a/security/apparmor/apparmorfs.c b/security/apparmor/apparmorfs.c
index 41073f7..be0b498 100644
--- a/security/apparmor/apparmorfs.c
+++ b/security/apparmor/apparmorfs.c
@@ -98,7 +98,7 @@ static struct aa_loaddata *aa_simple_write_to_buffer(const char __user *userbuf,
 		return ERR_PTR(-ESPIPE);
 
 	/* freed by caller to simple_write_to_buffer */
-	data = kvmalloc(sizeof(*data) + alloc_size);
+	data = kvmalloc(sizeof(*data) + alloc_size, GFP_KERNEL);
 	if (data == NULL)
 		return ERR_PTR(-ENOMEM);
 	kref_init(&data->count);
diff --git a/security/apparmor/include/lib.h b/security/apparmor/include/lib.h
index 0291ff3..550a700 100644
--- a/security/apparmor/include/lib.h
+++ b/security/apparmor/include/lib.h
@@ -64,17 +64,6 @@ char *aa_split_fqname(char *args, char **ns_name);
 const char *aa_splitn_fqname(const char *fqname, size_t n, const char **ns_name,
 			     size_t *ns_len);
 void aa_info_message(const char *str);
-void *__aa_kvmalloc(size_t size, gfp_t flags);
-
-static inline void *kvmalloc(size_t size)
-{
-	return __aa_kvmalloc(size, 0);
-}
-
-static inline void *kvzalloc(size_t size)
-{
-	return __aa_kvmalloc(size, __GFP_ZERO);
-}
 
 /**
  * aa_strneq - compare null terminated @str to a non null terminated substring
diff --git a/security/apparmor/lib.c b/security/apparmor/lib.c
index 32cafc1..7cd788a 100644
--- a/security/apparmor/lib.c
+++ b/security/apparmor/lib.c
@@ -129,36 +129,6 @@ void aa_info_message(const char *str)
 }
 
 /**
- * __aa_kvmalloc - do allocation preferring kmalloc but falling back to vmalloc
- * @size: how many bytes of memory are required
- * @flags: the type of memory to allocate (see kmalloc).
- *
- * Return: allocated buffer or NULL if failed
- *
- * It is possible that policy being loaded from the user is larger than
- * what can be allocated by kmalloc, in those cases fall back to vmalloc.
- */
-void *__aa_kvmalloc(size_t size, gfp_t flags)
-{
-	void *buffer = NULL;
-
-	if (size == 0)
-		return NULL;
-
-	/* do not attempt kmalloc if we need more than 16 pages at once */
-	if (size <= (16*PAGE_SIZE))
-		buffer = kmalloc(size, flags | GFP_KERNEL | __GFP_NORETRY |
-				 __GFP_NOWARN);
-	if (!buffer) {
-		if (flags & __GFP_ZERO)
-			buffer = vzalloc(size);
-		else
-			buffer = vmalloc(size);
-	}
-	return buffer;
-}
-
-/**
  * aa_policy_init - initialize a policy structure
  * @policy: policy to initialize  (NOT NULL)
  * @prefix: prefix name if any is required.  (MAYBE NULL)
diff --git a/security/apparmor/match.c b/security/apparmor/match.c
index eb0efef..960c913 100644
--- a/security/apparmor/match.c
+++ b/security/apparmor/match.c
@@ -88,7 +88,7 @@ static struct table_header *unpack_table(char *blob, size_t bsize)
 	if (bsize < tsize)
 		goto out;
 
-	table = kvzalloc(tsize);
+	table = kvzalloc(tsize, GFP_KERNEL);
 	if (table) {
 		table->td_id = th.td_id;
 		table->td_flags = th.td_flags;
diff --git a/security/apparmor/policy_unpack.c b/security/apparmor/policy_unpack.c
index 2e37c9c..f3422a9 100644
--- a/security/apparmor/policy_unpack.c
+++ b/security/apparmor/policy_unpack.c
@@ -487,7 +487,7 @@ fail:
 
 static void *kvmemdup(const void *src, size_t len)
 {
-	void *p = kvmalloc(len);
+	void *p = kvmalloc(len, GFP_KERNEL);
 
 	if (p)
 		memcpy(p, src, len);