Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon,  1 May 2023 09:54:31 -0700
In-Reply-To: <20230501165450.15352-1-surenb@google.com>
Mime-Version: 1.0
References: <20230501165450.15352-1-surenb@google.com>
Message-ID: <20230501165450.15352-22-surenb@google.com>
Subject: [PATCH 21/40] mm/page_ext: enable early_page_ext when CONFIG_MEM_ALLOC_PROFILING_DEBUG=y
From:   Suren Baghdasaryan <surenb@google.com>
To:     akpm@linux-foundation.org
Cc:     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, ldufour@linux.ibm.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, keescook@chromium.org,
        ndesaulniers@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,
        surenb@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
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

For all page allocations to be tagged, page_ext has to be initialized
before the first page allocation. Early tasks allocate their stacks
using page allocator before alloc_node_page_ext() initializes page_ext
area, unless early_page_ext is enabled. Therefore these allocations will
generate a warning when CONFIG_MEM_ALLOC_PROFILING_DEBUG is enabled.
Enable early_page_ext whenever CONFIG_MEM_ALLOC_PROFILING_DEBUG=y to
ensure page_ext initialization prior to any page allocation. This will
have all the negative effects associated with early_page_ext, such as
possible longer boot time, therefore we enable it only when debugging
with CONFIG_MEM_ALLOC_PROFILING_DEBUG enabled and not universally for
CONFIG_MEM_ALLOC_PROFILING.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
 mm/page_ext.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/mm/page_ext.c b/mm/page_ext.c
index eaf054ec276c..55ba797f8881 100644
--- a/mm/page_ext.c
+++ b/mm/page_ext.c
@@ -96,7 +96,16 @@ unsigned long page_ext_size;
 static unsigned long total_usage;
 struct page_ext *lookup_page_ext(const struct page *page);
 
+#ifdef CONFIG_MEM_ALLOC_PROFILING_DEBUG
+/*
+ * To ensure correct allocation tagging for pages, page_ext should be available
+ * before the first page allocation. Otherwise early task stacks will be
+ * allocated before page_ext initialization and missing tags will be flagged.
+ */
+bool early_page_ext __meminitdata = true;
+#else
 bool early_page_ext __meminitdata;
+#endif
 static int __init setup_early_page_ext(char *str)
 {
 	early_page_ext = true;
-- 
2.40.1.495.gc816e09b53d-goog