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Thu, 13 Aug 2026 09:29:41 +0000 X-Migadu-Flow: FLOW_OUT From: Ye Liu To: Michal Hocko , Andrew Morton Cc: Ye Liu , David Rientjes , Shakeel Butt , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] mm/oom_kill: simplify remaining RCU sections with scoped_guard(rcu) Date: Thu, 13 Aug 2026 17:29:32 +0800 Message-Id: <20260813092933.562028-1-ye.liu@linux.dev> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: 4if4wjkd3q8t7gx1ro64swngzojw61w1 X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: E99F2C0007 X-HE-Tag: 1786613382-461529 X-HE-Meta: U2FsdGVkX1/5aaL0G4Nam1bEhilS8M7siB4WhmBvYIvLF6KXiXKc6K8WSMgw6CpauIeGdS84pNugM3SwK5I76A5xcxop9SY+vfgEQn6BTvNJg706KiRk+hUhZ0TzG+OERZKOBHuzN6YPJmy6ubSeqpjtH4XPp9oZvb1RJeuilFcZ1g69eGaGOtnXqBeZkocRLcB19meSEhCvzroH9peaMa3pSgcatgsZH3VPizUwPYswZg52hulLHT8Lj9BslM4Bw9gabxanLXixSv805kophBc0zAUFD2bWLNK/g55rWXEkO6zrIqo24gMCSj7U9yUvl6X/BjNl9zTThOGNFRWfeXJSW2FpGE/rd5LUImfuZr3nCqnb4zh7F3x1wJ5BP0aOUjPjFzhz4mx7538BmuNjLhN5Q2TIktl+7Y4EWf7UwO9N1gXOQKGtt2QQYhy11NdKZNTJOGKqDEOaqITEKO5/RROr6DmMwzclWpW4I8WxGqjDU833bXCYiLGciVyB/qUbBCF+Fvlbp+q0hjdP1v4b4MC42cgc6vb/8Gvr1X2YiAcQt1nN9XWsSTQfaE+UQsK/W65PDWMTV6MSokseoKk3LrLu2alIqEEDT0RUhzmVK4sjgcRRLT7VoRrv8i4cXPHI4kIa9cZH0oW4RQPZrlbgxgN4cje2FlYtdc4eEvZqGjfbYlo8EA2ayUKYDwhh5mx5gWY3i/d5XWuzgZt/6O/7dpyXn4jeZ2+vtJtnmgcMBnf1ocM5wX7mh++u5MeQemQLxuSbZyCqhNtmbx5iYdZzVNPqWyhRRIhGODVvjkc4S5yv+Tj/OgIluU4xngsM9ijWuFCV2Cw+lJzaQM/I8TlFj0CvVHjtojgZ2sj/ItRgmEAEfkUYyOx5UQX7VrorjCjO4jNrKSHisStAz4DLEq8gmT0bpXHawGPaXL/3k5Q8gBQMsJ6JdDJDUbUJAJFWnlnE1HvFTj/RleV9bENclwY oDPedeg3 N5ECuIpPRyUkUMXdRVnEDUfMRYxrZkxPCFOVgapBYvFZd7V/1AcdJc5BWApuRVvEX6YTW3sdXRBG9Ak9/eaHWw8NQuQifkcLbABGPF53A6VYkBpVSW5FfAPuq/7VneCTraNdJZJT1zN1P2kPgZQvLIHl7ZcKITZCbPb+uSqTreSeHWURybIyGO0j/75AIJN8ZV+MUlU7ZHIFz50WBXerbIGyJefBlc4/h9hrjF/sN8P3e88SJGmtl1u1LhVMhgHfMbxISFHedW0FZT6rabPFm9no+85wmoowmzBtyfydJ0ZWHL0CyegwByR14tau+tZsjBqe+NIjysO983OQ= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Ye Liu Replace the remaining manual rcu_read_lock()/rcu_read_unlock() pairs in oom_cpuset_eligible(), select_bad_process(), dump_tasks(), task_will_free_mem(), and __oom_kill_process() with scoped_guard(rcu) for consistency and simpler control flow. scoped_guard(rcu) limits the RCU critical section to the loop body rather than the entire remaining function scope, making the protected region explicit and safer for future changes. Signed-off-by: Ye Liu --- v2: - Use scoped_guard instead of guard. - Link：https://lore.kernel.org/all/20260813032634.344946-1-ye.liu@linux.dev/ mm/oom_kill.c | 124 +++++++++++++++++++++++++------------------------- 1 file changed, 62 insertions(+), 62 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 5f372f6e26fa..0e8982e5be51 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -94,27 +94,27 @@ static bool oom_cpuset_eligible(struct task_struct *start, bool ret = false; const nodemask_t *mask = oc->nodemask; - rcu_read_lock(); - for_each_thread(start, tsk) { - if (mask) { - /* - * If this is a mempolicy constrained oom, tsk's - * cpuset is irrelevant. Only return true if its - * mempolicy intersects current, otherwise it may be - * needlessly killed. - */ - ret = mempolicy_in_oom_domain(tsk, mask); - } else { - /* - * This is not a mempolicy constrained oom, so only - * check the mems of tsk's cpuset. - */ - ret = cpuset_mems_allowed_intersects(current, tsk); + scoped_guard(rcu) { + for_each_thread(start, tsk) { + if (mask) { + /* + * If this is a mempolicy constrained oom, tsk's + * cpuset is irrelevant. Only return true if its + * mempolicy intersects current, otherwise it may be + * needlessly killed. + */ + ret = mempolicy_in_oom_domain(tsk, mask); + } else { + /* + * This is not a mempolicy constrained oom, so only + * check the mems of tsk's cpuset. + */ + ret = cpuset_mems_allowed_intersects(current, tsk); + } + if (ret) + break; } - if (ret) - break; } - rcu_read_unlock(); return ret; } @@ -368,11 +368,11 @@ static void select_bad_process(struct oom_control *oc) else { struct task_struct *p; - rcu_read_lock(); - for_each_process(p) - if (oom_evaluate_task(p, oc)) - break; - rcu_read_unlock(); + scoped_guard(rcu) { + for_each_process(p) + if (oom_evaluate_task(p, oc)) + break; + } } } @@ -430,14 +430,14 @@ static void dump_tasks(struct oom_control *oc) struct task_struct *p; int i = 0; - rcu_read_lock(); - for_each_process(p) { - /* Avoid potential softlockup warning */ - if ((++i & 1023) == 0) - touch_softlockup_watchdog(); - dump_task(p, oc); + scoped_guard(rcu) { + for_each_process(p) { + /* Avoid potential softlockup warning */ + if ((++i & 1023) == 0) + touch_softlockup_watchdog(); + dump_task(p, oc); + } } - rcu_read_unlock(); } } @@ -894,17 +894,17 @@ static bool task_will_free_mem(struct task_struct *task) * are dying as well to make sure that a) nobody pins its mm and * b) the task is also reapable by the oom reaper. */ - rcu_read_lock(); - for_each_process(p) { - if (!process_shares_mm(p, mm)) - continue; - if (same_thread_group(task, p)) - continue; - ret = __task_will_free_mem(p); - if (!ret) - break; + scoped_guard(rcu) { + for_each_process(p) { + if (!process_shares_mm(p, mm)) + continue; + if (same_thread_group(task, p)) + continue; + ret = __task_will_free_mem(p); + if (!ret) + break; + } } - rcu_read_unlock(); return ret; } @@ -960,29 +960,29 @@ static void __oom_kill_process(struct task_struct *victim, const char *message) * That thread will now get access to memory reserves since it has a * pending fatal signal. */ - rcu_read_lock(); - for_each_process(p) { - if (!process_shares_mm(p, mm)) - continue; - if (same_thread_group(p, victim)) - continue; - if (is_global_init(p)) { - can_oom_reap = false; - mm_flags_set(MMF_OOM_SKIP, mm); - pr_info("oom killer %d (%s) has mm pinned by %d (%s)\n", - task_pid_nr(victim), victim->comm, - task_pid_nr(p), p->comm); - continue; + scoped_guard(rcu) { + for_each_process(p) { + if (!process_shares_mm(p, mm)) + continue; + if (same_thread_group(p, victim)) + continue; + if (is_global_init(p)) { + can_oom_reap = false; + mm_flags_set(MMF_OOM_SKIP, mm); + pr_info("oom killer %d (%s) has mm pinned by %d (%s)\n", + task_pid_nr(victim), victim->comm, + task_pid_nr(p), p->comm); + continue; + } + /* + * No kthread_use_mm() user needs to read from the userspace so + * we are ok to reap it. + */ + if (unlikely(p->flags & PF_KTHREAD)) + continue; + do_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_TGID); } - /* - * No kthread_use_mm() user needs to read from the userspace so - * we are ok to reap it. - */ - if (unlikely(p->flags & PF_KTHREAD)) - continue; - do_send_sig_info(SIGKILL, SEND_SIG_PRIV, p, PIDTYPE_TGID); } - rcu_read_unlock(); if (can_oom_reap) queue_oom_reaper(victim); -- 2.25.1