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23 October 2021, 00:29:24 UTC
Revision 9f457179244a1c0316546b1760f8993d0d718861 authored by Johannes Weiner on 13 August 2020, 14:40:54 UTC, committed by Linus Torvalds on 13 August 2020, 19:15:21 UTC 
mm: memcontrol: fix warning when allocating the root cgroup
 
Commit 3e38e0aaca9e ("mm: memcg: charge memcg percpu memory to the
parent cgroup") adds memory tracking to the memcg kernel structures
themselves to make cgroups liable for the memory they are consuming
through the allocation of child groups (which can be significant).

This code is a bit awkward as it's spread out through several functions:
The outermost function does memalloc_use_memcg(parent) to set up
current->active_memcg, which designates which cgroup to charge, and the
inner functions pass GFP_ACCOUNT to request charging for specific
allocations.  To make sure this dependency is satisfied at all times -
to make sure we don't randomly charge whoever is calling the functions -
the inner functions warn on !current->active_memcg.

However, this triggers a false warning when the root memcg itself is
allocated.  No parent exists in this case, and so current->active_memcg
is rightfully NULL.  It's a false positive, not indicative of a bug.

Delete the warnings for now, we can revisit this later.

Fixes: 3e38e0aaca9e ("mm: memcg: charge memcg percpu memory to the parent cgroup")
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Acked-by: Roman Gushchin <guro@fb.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent dc06fe5
Raw File
Tip revision: 9f457179244a1c0316546b1760f8993d0d718861 authored by Johannes Weiner on 13 August 2020, 14:40:54 UTC
mm: memcontrol: fix warning when allocating the root cgroup
Tip revision: 9f45717
curve25519-generic.c 
// SPDX-License-Identifier: GPL-2.0-or-later

#include <crypto/curve25519.h>
#include <crypto/internal/kpp.h>
#include <crypto/kpp.h>
#include <linux/module.h>
#include <linux/scatterlist.h>

static int curve25519_set_secret(struct crypto_kpp *tfm, const void *buf,
				 unsigned int len)
{
	u8 *secret = kpp_tfm_ctx(tfm);

	if (!len)
		curve25519_generate_secret(secret);
	else if (len == CURVE25519_KEY_SIZE &&
		 crypto_memneq(buf, curve25519_null_point, CURVE25519_KEY_SIZE))
		memcpy(secret, buf, CURVE25519_KEY_SIZE);
	else
		return -EINVAL;
	return 0;
}

static int curve25519_compute_value(struct kpp_request *req)
{
	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
	const u8 *secret = kpp_tfm_ctx(tfm);
	u8 public_key[CURVE25519_KEY_SIZE];
	u8 buf[CURVE25519_KEY_SIZE];
	int copied, nbytes;
	u8 const *bp;

	if (req->src) {
		copied = sg_copy_to_buffer(req->src,
					   sg_nents_for_len(req->src,
							    CURVE25519_KEY_SIZE),
					   public_key, CURVE25519_KEY_SIZE);
		if (copied != CURVE25519_KEY_SIZE)
			return -EINVAL;
		bp = public_key;
	} else {
		bp = curve25519_base_point;
	}

	curve25519_generic(buf, secret, bp);

	/* might want less than we've got */
	nbytes = min_t(size_t, CURVE25519_KEY_SIZE, req->dst_len);
	copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst,
								nbytes),
				     buf, nbytes);
	if (copied != nbytes)
		return -EINVAL;
	return 0;
}

static unsigned int curve25519_max_size(struct crypto_kpp *tfm)
{
	return CURVE25519_KEY_SIZE;
}

static struct kpp_alg curve25519_alg = {
	.base.cra_name		= "curve25519",
	.base.cra_driver_name	= "curve25519-generic",
	.base.cra_priority	= 100,
	.base.cra_module	= THIS_MODULE,
	.base.cra_ctxsize	= CURVE25519_KEY_SIZE,

	.set_secret		= curve25519_set_secret,
	.generate_public_key	= curve25519_compute_value,
	.compute_shared_secret	= curve25519_compute_value,
	.max_size		= curve25519_max_size,
};

static int curve25519_init(void)
{
	return crypto_register_kpp(&curve25519_alg);
}

static void curve25519_exit(void)
{
	crypto_unregister_kpp(&curve25519_alg);
}

subsys_initcall(curve25519_init);
module_exit(curve25519_exit);

MODULE_ALIAS_CRYPTO("curve25519");
MODULE_ALIAS_CRYPTO("curve25519-generic");
MODULE_LICENSE("GPL");
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