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Tue, 15 Sep 2026 06:59:42 +0000 X-Mizu-Trace-ID: efae1140c7a24bc8 X-Migadu-Flow: FLOW_OUT From: Hao Ge To: Luis Chamberlain , Petr Pavlu , Daniel Gomez , Sami Tolvanen , Aaron Tomlin , Suren Baghdasaryan , Kent Overstreet , Hao Ge , Andrew Morton Cc: linux-modules@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Sashiko , stable@vger.kernel.org Subject: [PATCH v10 6/6] alloc_tag: Defer /proc/allocinfo removal to a workqueue Date: Tue, 15 Sep 2026 15:00:01 +0800 Message-Id: <20260915070001.113559-7-hao.ge@linux.dev> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20260915070001.113559-1-hao.ge@linux.dev> References: <20260915070001.113559-1-hao.ge@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: 4nzmtg4cgrx4uanirndce4mfsppsdory X-Rspamd-Queue-Id: C9F2B140005 X-Rspamd-Server: rspam07 X-HE-Tag: 1789455583-879210 X-HE-Meta: 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 Gn6dxfSm goRwW5hQWtIMNe7gVNY0dH30UNoNJgk5yq/I7D8V1pM0nCwdCRaGqjC9QwEqdhnuOOuogfD6BwL3oJaXkSjGKwH40XEiYHKPAM7GvQz6yhLWOBpgNs064BWh3ixNSjnk1Iwq/k2t1TrkuYrWWuCEviuslR9b6SQUopB9y7dGV74tuecPOWdmqNXoYd2jyotFSI/LY/ecl3DQAKKknyKnMl+3UkQv+eEbkHieiBqVIUqBw/m7OtptUV5Wtx92j4QW/N6p/jG7hJjajrdzYlKXDCEMe5V/4G2ODHoDMY/kjcnXkFsc= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: shutdown_mem_profiling() calls remove_proc_entry() from reserve_module_tags(), which runs under mod_lock held for write. remove_proc_entry() waits for readers, and a reader takes mod_lock for read in allocinfo_start(): CPU0 (insmod) CPU1 (read /proc/allocinfo) ---------------- ---------------------------- reserve_module_tags() down_write(&mod_lock) [held] use_pde() [in_use++] allocinfo_start() down_read(&mod_lock) <- blocks shutdown_mem_profiling() remove_proc_entry() wait for in_use == 0 <- blocks Move remove_proc_entry() to a workqueue. The file creation is moved to the end of alloc_tag_init() as well. If alloc_tag_init() fails with alloc_tag_cttype still NULL or an error pointer, a concurrent reader of the leftover file would dereference it in allocinfo_start() and panic. Reported-by: Sashiko Fixes: 4835f747d3ed ("alloc_tag: support for page allocation tag compression") Cc: stable@vger.kernel.org Signed-off-by: Hao Ge --- mm/alloc_tag.c | 26 +++++++++++++++++--------- 1 file changed, 17 insertions(+), 9 deletions(-) diff --git a/mm/alloc_tag.c b/mm/alloc_tag.c index 1ca0409b492b..cfa0fc84b68f 100644 --- a/mm/alloc_tag.c +++ b/mm/alloc_tag.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include @@ -591,6 +592,13 @@ void pgalloc_tag_swap(struct folio *new, struct folio *old) put_page_tag_ref(handle_new); } +static void remove_allocinfo_file(struct work_struct *work) +{ + remove_proc_entry(ALLOCINFO_FILE_NAME, NULL); +} + +static DECLARE_WORK(remove_allocinfo_work, remove_allocinfo_file); + static void shutdown_mem_profiling(bool remove_file) { if (mem_alloc_profiling_enabled()) @@ -600,7 +608,7 @@ static void shutdown_mem_profiling(bool remove_file) return; if (remove_file) - remove_proc_entry(ALLOCINFO_FILE_NAME, NULL); + schedule_work(&remove_allocinfo_work); mem_profiling_support = false; } @@ -1358,16 +1366,10 @@ static int __init alloc_tag_init(void) return 0; } - if (!proc_create(ALLOCINFO_FILE_NAME, 0400, NULL, &allocinfo_proc_ops)) { - pr_err("Failed to create %s file\n", ALLOCINFO_FILE_NAME); - shutdown_mem_profiling(false); - return -ENOMEM; - } - res = alloc_mod_tags_mem(); if (res) { pr_err("Failed to reserve address space for module tags, errno = %d\n", res); - shutdown_mem_profiling(true); + shutdown_mem_profiling(false); return res; } @@ -1375,10 +1377,16 @@ static int __init alloc_tag_init(void) if (IS_ERR(alloc_tag_cttype)) { pr_err("Allocation tags registration failed, errno = %pe\n", alloc_tag_cttype); free_mod_tags_mem(); - shutdown_mem_profiling(true); + shutdown_mem_profiling(false); return PTR_ERR(alloc_tag_cttype); } + if (!proc_create(ALLOCINFO_FILE_NAME, 0400, NULL, &allocinfo_proc_ops)) { + pr_err("Failed to create %s file\n", ALLOCINFO_FILE_NAME); + shutdown_mem_profiling(false); + return -ENOMEM; + } + return 0; } module_init(alloc_tag_init); -- 2.25.1