From: Suren Baghdasaryan <surenb@google.com>
Date: Tue, 9 Sep 2025 23:34:08 +0000 (-0700)
Subject: alloc_tag: prevent enabling memory profiling if it was shut down
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=feba2f597929deffc8cc3e332bfca0dec7ebe6e2;p=users%2Fjedix%2Flinux-maple.git

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/20250909233409.1013367-3-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Usama Arif <usamaarif642@gmail.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: David Wang <00107082@163.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

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
+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,
 	},
 };