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([216.195.201.23]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-36ca38d46fcsm9019567eec.13.2026.11.04.08.59.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 04 Nov 2026 08:59:27 -0800 (PST) From: Kunwu Chan To: paulmck@kernel.org, boqun@kernel.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, corbet@lwn.net, mingo@redhat.com, frederic@kernel.org, neeraj.upadhyay@kernel.org, josh@joshtriplett.org, urezki@gmail.com, dave@stgolabs.net Cc: stern@rowland.harvard.edu, parri.andrea@gmail.com, will@kernel.org, dhowells@redhat.com, j.alglave@ucl.ac.uk, luc.maranget@inria.fr, akiyks@gmail.com, dlustig@nvidia.com, joelagnelf@nvidia.com, skhan@linuxfoundation.org, rdunlap@infradead.org, longman@redhat.com, rostedt@goodmis.org, qiang.zhang@linux.dev, kunwu.chan@gmail.com, brads@mainlining.org, linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org, lkmm@lists.linux.dev, linux-doc@vger.kernel.org, rcu@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH 27/28] hazptr: Add Bloom false-positive exact-match fallback Date: Thu, 5 Nov 2026 00:54:45 +0800 Message-ID: <20261104165504.2430480-28-kunwu.chan@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20261104165504.2430480-1-kunwu.chan@gmail.com> References: <20261104165504.2430480-1-kunwu.chan@gmail.com> X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit After 200+ scan cycles without progress, do an exact-match per-address walk to determine whether the address is truly present in any per-CPU or overflow-list slot. If absent, complete the waiter immediately. A wildcard counts as present. Signed-off-by: Kunwu Chan --- kernel/hazptr.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) diff --git a/kernel/hazptr.c b/kernel/hazptr.c index 66954251c332..13ae9eb26a8b 100644 --- a/kernel/hazptr.c +++ b/kernel/hazptr.c @@ -407,6 +407,7 @@ struct hazptr_waiter { #endif #ifdef CONFIG_HAZPTR_DRAIN_ASSIST unsigned int drain_cycles; + unsigned int bloom_cycles; /* cycles since last exact match */ #endif }; @@ -852,6 +853,18 @@ static void hazptr_scan_do_cycle(void) mutex_unlock(&hazptr_phase_lock); + /* Bloom-false-positive fallback */ + list_for_each_entry_safe(w, n, &hazptr_scan.scanning, node) { + w->bloom_cycles++; + if (w->bloom_cycles > 200) { + if (!hazptr_scan_walk(w->addr, NULL, NULL)) { + list_move(&w->node, &done); + } else { + w->bloom_cycles = 0; + } + } + } + list_for_each_entry_safe(w, n, &done, node) { list_del_init(&w->node); complete(&w->done); -- 2.43.0