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AJvYcCUGs7SSdlZmaGf93DPDEp7D2qEr7ZxkK9dYoSSdiBet3a+9ybTKQRaoxTZIgCwNEnk1TBAryMd5fA==@kvack.org X-Gm-Message-State: AOJu0YwpjJWYT2KSGm28/FwlsvrgE4+A5RH5H1Q1jWDAiiLKs8DzgOAY /YOL2lkvDkmxz2c7SG+Y5TfATfUts14qWLzxYwUZ/AOUmJmfBe8ut2za1VBUhJLm6QvfVmI2eFC OQV7BGw== X-Google-Smtp-Source: AGHT+IHLhrKsU7MdJp99+KvZZ/xCoXmF9qcszyx5DJq3SSgN+PpZivt51xKlhmqSsW0XWVKbU/tASHuysvs= X-Received: from dynm33.prod.google.com ([2002:a05:7300:2aa1:b0:2a4:664f:e91d]) (user=surenb job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7301:4d10:b0:2a4:3593:ddf2 with SMTP id 5a478bee46e88-2ab92e671a4mr4465065eec.31.1764886200002; Thu, 04 Dec 2025 14:10:00 -0800 (PST) Date: Thu, 4 Dec 2025 14:09:56 -0800 Mime-Version: 1.0 X-Mailer: git-send-email 2.52.0.223.gf5cc29aaa4-goog Message-ID: <20251204220957.360838-1-surenb@google.com> Subject: [PATCH 1/1] alloc_tag: skip rcu barrier on module unload if profiling was not enabled From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: kent.overstreet@linux.dev, vbabka@suse.cz, harry.yoo@oracle.com, da.gomez@kernel.org, jonathanh@nvidia.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, Suren Baghdasaryan Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 6A474140014 X-Rspamd-Server: rspam02 X-Stat-Signature: w6nrrbi4grd75g6swsqc7ahzjutn3dtc X-Rspam-User: X-HE-Tag: 1764886201-575755 X-HE-Meta: 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 oXIsNman 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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: RCU barrier in the module unload path is needed to ensure all kfree_rcu operations which modify tag counters are complete before we free the tags. However this is not necessary if memory allocation profiling was never enabled on the system. Introduce a sticky flag that records whether memory profiling was ever enabled and make the RCU barrier conditional. Suggested-by: Vlastimil Babka Signed-off-by: Suren Baghdasaryan --- Applies over mm-new include/linux/codetag.h | 2 ++ lib/alloc_tag.c | 11 ++++++++++- lib/codetag.c | 14 ++++++++++++-- 3 files changed, 24 insertions(+), 3 deletions(-) diff --git a/include/linux/codetag.h b/include/linux/codetag.h index 8ea2a5f7c98a..8a07a83cabdd 100644 --- a/include/linux/codetag.h +++ b/include/linux/codetag.h @@ -95,6 +95,7 @@ void codetag_free_module_sections(struct module *mod); void codetag_module_replaced(struct module *mod, struct module *new_mod); int codetag_load_module(struct module *mod); void codetag_unload_module(struct module *mod); +void codetag_flush_rcu_on_module_unload(void); #else /* defined(CONFIG_CODE_TAGGING) && defined(CONFIG_MODULES) */ @@ -109,6 +110,7 @@ static inline void codetag_free_module_sections(struct module *mod) {} static inline void codetag_module_replaced(struct module *mod, struct module *new_mod) {} static inline int codetag_load_module(struct module *mod) { return 0; } static inline void codetag_unload_module(struct module *mod) {} +static inline void codetag_flush_rcu_on_module_unload(void) {} #endif /* defined(CONFIG_CODE_TAGGING) && defined(CONFIG_MODULES) */ diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c index 27fee57a5c91..173eebfacb1e 100644 --- a/lib/alloc_tag.c +++ b/lib/alloc_tag.c @@ -776,10 +776,16 @@ EXPORT_SYMBOL(page_alloc_tagging_ops); static int proc_mem_profiling_handler(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { + int ret; + if (!mem_profiling_support && write) return -EINVAL; - return proc_do_static_key(table, write, buffer, lenp, ppos); + ret = proc_do_static_key(table, write, buffer, lenp, ppos); + if (!ret && write && mem_alloc_profiling_enabled()) + codetag_flush_rcu_on_module_unload(); + + return ret; } @@ -829,6 +835,9 @@ static int __init alloc_tag_init(void) return 0; } + if (mem_alloc_profiling_enabled()) + codetag_flush_rcu_on_module_unload(); + if (!proc_create_seq_private(ALLOCINFO_FILE_NAME, 0400, NULL, &allocinfo_seq_op, sizeof(struct allocinfo_private), NULL)) { pr_err("Failed to create %s file\n", ALLOCINFO_FILE_NAME); diff --git a/lib/codetag.c b/lib/codetag.c index 545911cebd25..ed6d6425b62a 100644 --- a/lib/codetag.c +++ b/lib/codetag.c @@ -34,6 +34,7 @@ struct codetag_module { static DEFINE_MUTEX(codetag_lock); static LIST_HEAD(codetag_types); +static bool flush_rcu_on_module_unload; void codetag_lock_module_list(struct codetag_type *cttype, bool lock) { @@ -335,6 +336,11 @@ int codetag_load_module(struct module *mod) return ret; } +void codetag_flush_rcu_on_module_unload(void) +{ + flush_rcu_on_module_unload = true; +} + void codetag_unload_module(struct module *mod) { struct codetag_type *cttype; @@ -342,8 +348,12 @@ void codetag_unload_module(struct module *mod) if (!mod) return; - /* await any module's kfree_rcu() operations to complete */ - kvfree_rcu_barrier(); + /* + * Await any module's kfree_rcu() operations to complete + * if profiling was ever enabled. + */ + if (flush_rcu_on_module_unload) + kvfree_rcu_barrier(); mutex_lock(&codetag_lock); list_for_each_entry(cttype, &codetag_types, link) { base-commit: 3f43be96f919cc611dcb2a4e38dd464831f4513e -- 2.52.0.223.gf5cc29aaa4-goog