Received-SPF: pass (google.com: domain of linux-kernel+bounces-62561-linux.lists.archive=gmail.com@vger.kernel.org designates 2604:1380:45d1:ec00::1 as permitted sender) client-ip=2604:1380:45d1:ec00::1;
Date: Mon, 12 Feb 2024 16:10:02 -0800
From: Kees Cook <keescook@chromium.org>
To: Suren Baghdasaryan <surenb@google.com>
Cc: akpm@linux-foundation.org, kent.overstreet@linux.dev, mhocko@suse.com,
	vbabka@suse.cz, hannes@cmpxchg.org, roman.gushchin@linux.dev,
	mgorman@suse.de, dave@stgolabs.net, willy@infradead.org,
	liam.howlett@oracle.com, corbet@lwn.net, void@manifault.com,
	peterz@infradead.org, juri.lelli@redhat.com,
	catalin.marinas@arm.com, will@kernel.org, arnd@arndb.de,
	tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com,
	x86@kernel.org, peterx@redhat.com, david@redhat.com,
	axboe@kernel.dk, mcgrof@kernel.org, masahiroy@kernel.org,
	nathan@kernel.org, dennis@kernel.org, tj@kernel.org,
	muchun.song@linux.dev, rppt@kernel.org, paulmck@kernel.org,
	pasha.tatashin@soleen.com, yosryahmed@google.com, yuzhao@google.com,
	dhowells@redhat.com, hughd@google.com, andreyknvl@gmail.com,
	ndesaulniers@google.com, vvvvvv@google.com,
	gregkh@linuxfoundation.org, ebiggers@google.com, ytcoode@gmail.com,
	vincent.guittot@linaro.org, dietmar.eggemann@arm.com,
	rostedt@goodmis.org, bsegall@google.com, bristot@redhat.com,
	vschneid@redhat.com, cl@linux.com, penberg@kernel.org,
	iamjoonsoo.kim@lge.com, 42.hyeyoo@gmail.com, glider@google.com,
	elver@google.com, dvyukov@google.com, shakeelb@google.com,
	songmuchun@bytedance.com, jbaron@akamai.com, rientjes@google.com,
	minchan@google.com, kaleshsingh@google.com, kernel-team@android.com,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	iommu@lists.linux.dev, linux-arch@vger.kernel.org,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
	linux-modules@vger.kernel.org, kasan-dev@googlegroups.com,
	cgroups@vger.kernel.org
Subject: Re: [PATCH v3 31/35] lib: add memory allocations report in show_mem()
Message-ID: <202402121606.687E798B@keescook>
References: <20240212213922.783301-1-surenb@google.com>
 <20240212213922.783301-32-surenb@google.com>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20240212213922.783301-32-surenb@google.com>

On Mon, Feb 12, 2024 at 01:39:17PM -0800, Suren Baghdasaryan wrote:
> Include allocations in show_mem reports.
> 
> Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> ---
>  include/linux/alloc_tag.h |  2 ++
>  lib/alloc_tag.c           | 38 ++++++++++++++++++++++++++++++++++++++
>  mm/show_mem.c             | 15 +++++++++++++++
>  3 files changed, 55 insertions(+)
> 
> diff --git a/include/linux/alloc_tag.h b/include/linux/alloc_tag.h
> index 3fe51e67e231..0a5973c4ad77 100644
> --- a/include/linux/alloc_tag.h
> +++ b/include/linux/alloc_tag.h
> @@ -30,6 +30,8 @@ struct alloc_tag {
>  
>  #ifdef CONFIG_MEM_ALLOC_PROFILING
>  
> +void alloc_tags_show_mem_report(struct seq_buf *s);
> +
>  static inline struct alloc_tag *ct_to_alloc_tag(struct codetag *ct)
>  {
>  	return container_of(ct, struct alloc_tag, ct);
> diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
> index 2d5226d9262d..54312c213860 100644
> --- a/lib/alloc_tag.c
> +++ b/lib/alloc_tag.c
> @@ -96,6 +96,44 @@ static const struct seq_operations allocinfo_seq_op = {
>  	.show	= allocinfo_show,
>  };
>  
> +void alloc_tags_show_mem_report(struct seq_buf *s)
> +{
> +	struct codetag_iterator iter;
> +	struct codetag *ct;
> +	struct {
> +		struct codetag		*tag;
> +		size_t			bytes;
> +	} tags[10], n;
> +	unsigned int i, nr = 0;
> +
> +	codetag_lock_module_list(alloc_tag_cttype, true);
> +	iter = codetag_get_ct_iter(alloc_tag_cttype);
> +	while ((ct = codetag_next_ct(&iter))) {
> +		struct alloc_tag_counters counter = alloc_tag_read(ct_to_alloc_tag(ct));
> +
> +		n.tag	= ct;
> +		n.bytes = counter.bytes;
> +
> +		for (i = 0; i < nr; i++)
> +			if (n.bytes > tags[i].bytes)
> +				break;
> +
> +		if (i < ARRAY_SIZE(tags)) {
> +			nr -= nr == ARRAY_SIZE(tags);
> +			memmove(&tags[i + 1],
> +				&tags[i],
> +				sizeof(tags[0]) * (nr - i));
> +			nr++;
> +			tags[i] = n;
> +		}
> +	}
> +
> +	for (i = 0; i < nr; i++)
> +		alloc_tag_to_text(s, tags[i].tag);
> +
> +	codetag_lock_module_list(alloc_tag_cttype, false);
> +}
> +
>  static void __init procfs_init(void)
>  {
>  	proc_create_seq("allocinfo", 0444, NULL, &allocinfo_seq_op);
> diff --git a/mm/show_mem.c b/mm/show_mem.c
> index 8dcfafbd283c..d514c15ca076 100644
> --- a/mm/show_mem.c
> +++ b/mm/show_mem.c
> @@ -12,6 +12,7 @@
>  #include <linux/hugetlb.h>
>  #include <linux/mm.h>
>  #include <linux/mmzone.h>
> +#include <linux/seq_buf.h>
>  #include <linux/swap.h>
>  #include <linux/vmstat.h>
>  
> @@ -423,4 +424,18 @@ void __show_mem(unsigned int filter, nodemask_t *nodemask, int max_zone_idx)
>  #ifdef CONFIG_MEMORY_FAILURE
>  	printk("%lu pages hwpoisoned\n", atomic_long_read(&num_poisoned_pages));
>  #endif
> +#ifdef CONFIG_MEM_ALLOC_PROFILING
> +	{
> +		struct seq_buf s;
> +		char *buf = kmalloc(4096, GFP_ATOMIC);

Why 4096? Maybe use PAGE_SIZE instead?

> +
> +		if (buf) {
> +			printk("Memory allocations:\n");

This needs a printk prefix, or better yet, just use pr_info() or similar.

> +			seq_buf_init(&s, buf, 4096);
> +			alloc_tags_show_mem_report(&s);
> +			printk("%s", buf);

Once a seq_buf "consumes" a char *, please don't use any directly any
more. This should be:

			pr_info("%s", seq_buf_str(s));

Otherwise %NUL termination isn't certain. Very likely, given the use
case here, but let's use good hygiene. :)

> +			kfree(buf);
> +		}
> +	}
> +#endif
>  }
> -- 
> 2.43.0.687.g38aa6559b0-goog
> 

-- 
Kees Cook