Commit 9e8a0bbb authored Sep 15, 2025 by Suren Baghdasaryan Committed by Andrew Morton Sep 21, 2025

alloc_tag: prevent enabling memory profiling if it was shut down

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.

Link: https://lkml.kernel.org/r/20250915212756.3998938-3-surenb@google.com


Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: Usama Arif <usamaarif642@gmail.com>
Cc: David Wang <00107082@163.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

parent 123bcf28

lib/alloc_tag.c

+15 −1

Original line number	Diff line number	Diff line
		@@ -766,6 +766,20 @@ struct page_ext_operations page_alloc_tagging_ops = {
		EXPORT_SYMBOL(page_alloc_tagging_ops);

		#ifdef CONFIG_SYSCTL
		/*
		* Not using proc_do_static_key() directly to prevent enabling profiling
		* after it was shut down.
		*/
		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",
		@@ -775,7 +789,7 @@ static struct ctl_table memory_allocation_profiling_sysctls[] = {
		#else
		.mode = 0644,
		#endif
		.proc_handler = proc_do_static_key,
		.proc_handler = proc_mem_profiling_handler,
		},
		};