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[94.245.46.61]) by smtp.gmail.com with ESMTPSA id o16sm730253lfu.228.2021.04.28.06.45.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Apr 2021 06:45:09 -0700 (PDT) From: "Uladzislau Rezki (Sony)" To: LKML , RCU , "Paul E . McKenney" Cc: Michal Hocko , Andrew Morton , Daniel Axtens , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Peter Zijlstra , Thomas Gleixner , "Theodore Y . Ts'o" , Sebastian Andrzej Siewior , Uladzislau Rezki , Oleksiy Avramchenko Subject: [PATCH v1 5/5] kvfree_rcu: Fix comments according to current code Date: Wed, 28 Apr 2021 15:44:22 +0200 Message-Id: <20210428134422.1894-5-urezki@gmail.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20210428134422.1894-1-urezki@gmail.com> References: <20210428134422.1894-1-urezki@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org We used to have an "emergency path" and comments related to it. According to current kvfree_rcu() design that path is not considered as emergency anymore. This patch rephrases and updates comments regarding this. Signed-off-by: Uladzislau Rezki (Sony) --- kernel/rcu/tree.c | 15 +++++++++------ 1 file changed, 9 insertions(+), 6 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 229e909ad437..91b978e90c3b 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3332,9 +3332,11 @@ static void kfree_rcu_work(struct work_struct *work) } /* - * Emergency case only. It can happen under low memory - * condition when an allocation gets failed, so the "bulk" - * path can not be temporary maintained. + * This is used when the "bulk" path can not be temporary + * maintained for the double-argument of kvfree_rcu(). It + * happens because a page-cache is empty, thus objects are + * queued to the linked-list instead. This path is named + * as "Channel 3". */ for (; head; head = next) { unsigned long offset = (unsigned long)head->func; @@ -3380,8 +3382,8 @@ static inline bool queue_kfree_rcu_work(struct kfree_rcu_cpu *krcp) if ((krcp->bkvhead[0] && !krwp->bkvhead_free[0]) || (krcp->bkvhead[1] && !krwp->bkvhead_free[1]) || (krcp->head && !krwp->head_free)) { - // Channel 1 corresponds to SLAB ptrs. - // Channel 2 corresponds to vmalloc ptrs. + // Channel 1 corresponds to SLAB ptrs. bulk path. + // Channel 2 corresponds to vmalloc ptrs. bulk path. for (j = 0; j < FREE_N_CHANNELS; j++) { if (!krwp->bkvhead_free[j]) { krwp->bkvhead_free[j] = krcp->bkvhead[j]; @@ -3389,7 +3391,8 @@ static inline bool queue_kfree_rcu_work(struct kfree_rcu_cpu *krcp) } } - // Channel 3 corresponds to emergency path. + // Channel 3 corresponds to objects queued to the + // linked-list for both SLAB and vmalloc pointers. if (!krwp->head_free) { krwp->head_free = krcp->head; krcp->head = NULL; -- 2.20.1