From: Steven Rostedt <rostedt@goodmis.org>
To: Kalesh Singh <kaleshsingh@google.com>
Cc: akpm@linux-foundation.org, minchan@kernel.org,
lorenzo.stoakes@oracle.com, david@redhat.com,
Liam.Howlett@oracle.com, rppt@kernel.org, pfalcato@suse.de,
kernel-team@android.com, android-mm@google.com,
Alexander Viro <viro@zeniv.linux.org.uk>,
Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
Kees Cook <kees@kernel.org>, Vlastimil Babka <vbabka@suse.cz>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Vincent Guittot <vincent.guittot@linaro.org>,
Dietmar Eggemann <dietmar.eggemann@arm.com>,
Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
Valentin Schneider <vschneid@redhat.com>,
Jann Horn <jannh@google.com>, Shuah Khan <shuah@kernel.org>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org,
linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v2 7/7] mm/tracing: introduce max_vma_count_exceeded trace event
Date: Tue, 16 Sep 2025 14:02:45 -0400 [thread overview]
Message-ID: <20250916140245.5894a2aa@gandalf.local.home> (raw)
In-Reply-To: <CAC_TJvc6aqjBRZ05wyGb49AU+-aKpSph=ZSk3fdV2xraXi-_nQ@mail.gmail.com>
On Tue, 16 Sep 2025 10:57:43 -0700
Kalesh Singh <kaleshsingh@google.com> wrote:
> > BTW, why the hash of the mm pointer and not the pointer itself? We save
> > pointers in lots of places, and if it is the pointer, you could use an
> > eprobe to attache to the trace event to dereference its fields.
>
> In Android we try to avoid exposing raw kernel pointers to userspace
> for security reasons: raising /proc/sys/kernel/kptr_restrict to 2
> immediately after symbols are resolved for necessary telemetry tooling
> during early boot. I believe this is also why rss_stat uses the hash
> and not the raw pointer.
When it comes to tracing, you already lost. If it goes into the ring buffer
it's a raw pointer. BPF doesn't use the output of the trace event, so you
are exposing nothing from that. It uses the proto directly.
Heck, if you enable function tracing, you are exposing every function
address it traces via the raw data output.
-- Steve
next prev parent reply other threads:[~2025-09-16 18:01 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-15 16:36 [PATCH v2 0/7] vma count: fixes, test and improvements Kalesh Singh
2025-09-15 16:36 ` [PATCH v2 1/7] mm: fix off-by-one error in VMA count limit checks Kalesh Singh
2025-09-15 22:36 ` Andrew Morton
2025-09-16 14:20 ` Jonathan Corbet
2025-09-17 1:16 ` Andrew Morton
2025-09-16 9:45 ` Pedro Falcato
2025-09-17 7:44 ` SeongJae Park
2025-09-17 10:52 ` David Hildenbrand
2025-09-18 11:31 ` Pedro Falcato
2025-09-18 13:53 ` Lorenzo Stoakes
2025-09-15 16:36 ` [PATCH v2 2/7] mm/selftests: add max_vma_count tests Kalesh Singh
2025-09-17 10:58 ` David Hildenbrand
2025-09-17 16:49 ` Kalesh Singh
2025-09-18 14:42 ` Lorenzo Stoakes
2025-09-18 16:21 ` Kalesh Singh
2025-09-15 16:36 ` [PATCH v2 3/7] mm: introduce vma_count_remaining() Kalesh Singh
2025-09-17 13:38 ` David Hildenbrand
2025-09-17 17:10 ` Kalesh Singh
2025-09-18 13:20 ` Lorenzo Stoakes
2025-09-18 13:26 ` Lorenzo Stoakes
2025-09-18 14:31 ` Lorenzo Stoakes
2025-09-18 15:52 ` Kalesh Singh
2025-09-15 16:36 ` [PATCH v2 4/7] mm: rename mm_struct::map_count to vma_count Kalesh Singh
2025-09-17 13:41 ` David Hildenbrand
2025-09-18 11:46 ` Pedro Falcato
2025-09-18 14:48 ` Lorenzo Stoakes
2025-09-15 16:36 ` [PATCH v2 5/7] mm: harden vma_count against direct modification Kalesh Singh
2025-09-18 14:52 ` Lorenzo Stoakes
2025-09-18 15:43 ` Kalesh Singh
2025-09-15 16:36 ` [PATCH v2 6/7] mm: add assertion for VMA count limit Kalesh Singh
2025-09-17 13:44 ` David Hildenbrand
2025-09-17 17:22 ` Kalesh Singh
2025-09-17 18:34 ` David Hildenbrand
2025-09-17 20:31 ` Kalesh Singh
2025-09-18 11:48 ` Pedro Falcato
2025-09-18 13:30 ` Lorenzo Stoakes
2025-09-15 16:36 ` [PATCH v2 7/7] mm/tracing: introduce max_vma_count_exceeded trace event Kalesh Singh
2025-09-15 23:41 ` Steven Rostedt
2025-09-16 1:19 ` Kalesh Singh
2025-09-16 15:52 ` Steven Rostedt
2025-09-16 17:36 ` Kalesh Singh
2025-09-16 17:48 ` Steven Rostedt
2025-09-16 17:57 ` Kalesh Singh
2025-09-16 18:02 ` Steven Rostedt [this message]
2025-09-16 18:23 ` Kalesh Singh
2025-09-16 18:51 ` Steven Rostedt
2025-09-16 20:08 ` Kalesh Singh
2025-09-18 11:38 ` Pedro Falcato
2025-09-18 14:48 ` Steven Rostedt
2025-09-18 13:42 ` Lorenzo Stoakes
2025-09-18 13:51 ` Lorenzo Stoakes
2025-09-18 15:55 ` Kalesh Singh
2025-09-15 22:34 ` [PATCH v2 0/7] vma count: fixes, test and improvements Andrew Morton
2025-09-15 23:10 ` Kalesh Singh
2025-09-16 0:05 ` Andrew Morton
2025-09-16 1:23 ` Kalesh Singh
2025-09-16 10:12 ` Lorenzo Stoakes
2025-09-16 17:47 ` Kalesh Singh
2025-09-17 2:16 ` Andrew Morton
2025-09-17 5:36 ` Lorenzo Stoakes
2025-09-17 23:32 ` Andrew Morton
2025-09-18 10:29 ` Lorenzo Stoakes
2025-09-18 12:07 ` David Hildenbrand
2025-09-18 12:49 ` Lorenzo Stoakes
2025-09-18 20:59 ` Andrew Morton
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