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Wed, 10 Sep 2025 13:52:04 -0700 (PDT) Message-ID: <8c4967ca-a125-458f-9998-6de4f8257dd5@gmail.com> Date: Wed, 10 Sep 2025 16:51:57 -0400 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 2/3] alloc_tag: prevent enabling memory profiling if it was shut down Content-Language: en-GB To: Suren Baghdasaryan , akpm@linux-foundation.org Cc: kent.overstreet@linux.dev, vbabka@suse.cz, mhocko@suse.com, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, shakeel.butt@linux.dev, 00107082@163.com, pasha.tatashin@soleen.com, souravpanda@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20250909233409.1013367-1-surenb@google.com> <20250909233409.1013367-3-surenb@google.com> From: Usama Arif In-Reply-To: <20250909233409.1013367-3-surenb@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: BA47E160007 X-Stat-Signature: 7eqziiu191cy81jj7z7ahzmmryqouses X-HE-Tag: 1757537525-732847 X-HE-Meta: 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 mZro40yY 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 10/09/2025 00:34, Suren Baghdasaryan wrote: > Memory profiling can be shut down due to reasons like a failure during > initialization. When this happens, the user should not be able to > re-enable it. Current sysctrl interface does not handle this properly > and will allow re-enabling memory profiling. Fix this by checking for > this condition during sysctrl write operation. > > Signed-off-by: Suren Baghdasaryan > --- > lib/alloc_tag.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > Acked-by: Usama Arif > diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c > index 95688c4cba7a..79891528e7b6 100644 > --- a/lib/alloc_tag.c > +++ b/lib/alloc_tag.c > @@ -767,6 +767,16 @@ struct page_ext_operations page_alloc_tagging_ops = { > EXPORT_SYMBOL(page_alloc_tagging_ops); > > #ifdef CONFIG_SYSCTL nit: might be good to add a comment here that we are not using default as we dont want to enable it back if it fails once. But not worth a respin as someone can always check git log if curious. > +static int proc_mem_profiling_handler(const struct ctl_table *table, int write, > + void *buffer, size_t *lenp, loff_t *ppos) > +{ > + if (!mem_profiling_support && write) > + return -EINVAL; > + > + return proc_do_static_key(table, write, buffer, lenp, ppos); > +} > + > + > static struct ctl_table memory_allocation_profiling_sysctls[] = { > { > .procname = "mem_profiling", > @@ -776,7 +786,7 @@ static struct ctl_table memory_allocation_profiling_sysctls[] = { > #else > .mode = 0644, > #endif > - .proc_handler = proc_do_static_key, > + .proc_handler = proc_mem_profiling_handler, > }, > }; >