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a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1791827730; bh=J6n50eQ6V6pm/yCK3IlU6OVvJN5nG9cOEO098JYwwjc=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=BVrURADp1C8qVzrqLzvEPNHgiBxziCjaeMHJ0+mFb6UlZRKScmQV7vpqt/3eMKKBf Kt1OVCcCSI5QxX27NGiDPfN6DnmsKHHBzNWExVlaijVqx98s6g+04t7Qha0RzzU+cm EU36JDQ9rY/7RdGGhcJgswDE11gV62/RoITeMTPtTSbRV/lJMsD0+T2+lw5+27XDeZ NSIEfvd8kHFDWoeeMCgo96BzPS31dyiC1FJkZLXFwNVhgWaJZ6epV8PYaBoAtbdnQW KLpAmZeDS4J92RhFNACKOzt/BNJ6RTT1HruDVrTS74WhOCBTEDymQI0hNNKqq/V7mL X5vM3rxGFOIrg== Message-ID: <38befa8c-3885-44eb-813c-0ee34cd55248@kernel.org> Date: Mon, 12 Oct 2026 19:55:25 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH net-next v6 2/8] ipc, msg: Account msg_msg allocations with GFP_KERNEL_ACCOUNT again Content-Language: en-US To: Kees Cook Cc: Christian Brauner , Jan Kara , Andrew Morton , Roman Gushchin , Johannes Weiner , Michal Hocko , Shakeel Butt , Muchun Song , cgroups@vger.kernel.org, linux-mm@kvack.org, Pedro Falcato , Kuniyuki Iwashima , linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org References: <20261006092030.got.500-kees@kernel.org> <20261006092035.166776-2-kees@kernel.org> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: 4ern46r3ghe5s5skxi55b4ua64feu6uw X-Rspam-User: X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 0E0C3100008 X-HE-Tag: 1791827730-515104 X-HE-Meta: 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 ja4kuRbb 9IGjYFxtpPZo6+10bUxwerMkw7kSOHcQmbLCIYgr7xMzz7ZmaPEvnADDhdK3JUVqvxg4Y0GuyAc+fKeUl0sMLrIVYVZYRIypcL6Ye0myOfqss10FkvfpUmTu0a0QazD/7HTsHis2hlU3zWeu0B0JoFG03Ae1rwDMphrpRxy5l515IqW7SAss6qO0VIRnQAW67rz6/8ZMDL9gLzIzw6sgKNhigetC6Zl5XxDOG39j5cklae039DLVg6MCkAW5V/1ie0kht29gGvGrwrXDNdWE8LJmcpt5jFgNNxFAOVt3z2KFVgUgt2oP6LMTYT1nAvxIuaZ+7lWLsEpl3dzg= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/6/26 11:20, Kees Cook wrote: > Since commit 734bbc1c97ea7 ("ipc, msg: Use dedicated slab buckets for > alloc_msg()"), alloc_msg() allocates with GFP_KERNEL, and a msg_msg is > accounted only through SLAB_ACCOUNT on its bucket caches. With > CONFIG_SLAB_BUCKETS=n, kmem_buckets_create() creates no caches and > kmem_buckets_alloc() is a GFP_KERNEL kmalloc() from the general caches, > which do not account it; the same happens when kmem_buckets_create() > fails. Either way, the allocation is not charged to the sender's memory > cgroup. > > Allocate with GFP_KERNEL_ACCOUNT again, as before that commit. Memcg > charges such an allocation in whichever cache serves it, so drop the > SLAB_ACCOUNT, which no longer adds anything. > > Build tested ARCH=x86_64 defconfig with GCC 16.2.0, with > CONFIG_SLAB_BUCKETS as y and n. > > Fixes: 734bbc1c97ea7 ("ipc, msg: Use dedicated slab buckets for alloc_msg()") > Assisted-by: LLM > Signed-off-by: Kees Cook Could we, for the purposes of a backportable fix, just have both SLAB_ACCOUNT and GFP_KERNEL_ACCOUNT in place? That should do the right thing regardless of CONFIG_SLAB_BUCKETS state, no? > --- > ipc/msgutil.c | 5 +++-- > 1 file changed, 3 insertions(+), 2 deletions(-) > > diff --git a/ipc/msgutil.c b/ipc/msgutil.c > index e28f0cecb2ec..1ba8e59cb255 100644 > --- a/ipc/msgutil.c > +++ b/ipc/msgutil.c > @@ -43,7 +43,7 @@ static kmem_buckets *msg_buckets __ro_after_init; > > static int __init init_msg_buckets(void) > { > - msg_buckets = kmem_buckets_create("msg_msg", SLAB_ACCOUNT, > + msg_buckets = kmem_buckets_create("msg_msg", 0, > sizeof(struct msg_msg), > DATALEN_MSG, NULL); > > @@ -58,7 +58,8 @@ static struct msg_msg *alloc_msg(size_t len) > size_t alen; > > alen = min(len, DATALEN_MSG); > - msg = kmem_buckets_alloc(msg_buckets, sizeof(*msg) + alen, GFP_KERNEL); > + msg = kmem_buckets_alloc(msg_buckets, sizeof(*msg) + alen, > + GFP_KERNEL_ACCOUNT); > if (msg == NULL) > return NULL; >