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Tue, 08 Apr 2025 05:29:49 -0700 (PDT) From: Lance Yang To: akpm@linux-foundation.org Cc: amaindex@outlook.com, anna.schumaker@oracle.com, boqun.feng@gmail.com, ioworker0@gmail.com, joel.granados@kernel.org, jstultz@google.com, kent.overstreet@linux.dev, leonylgao@tencent.com, linux-kernel@vger.kernel.org, longman@redhat.com, mhiramat@kernel.org, mingo@redhat.com, mingzhe.yang@ly.com, peterz@infradead.org, rostedt@goodmis.org, senozhatsky@chromium.org, tfiga@chromium.org, will@kernel.org Subject: Re: [PATCH v4 1/3] hung_task: replace blocker_mutex with encoded blocker Date: Tue, 8 Apr 2025 20:29:37 +0800 Message-ID: <20250408122939.84154-1-ioworker0@gmail.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250407130825.69b4c879b242df4caaf426cf@linux-foundation.org> References: <20250407130825.69b4c879b242df4caaf426cf@linux-foundation.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On Tue, Apr 8, 2025 at 4:08 AM Andrew Morton wrote: > > On Thu, 20 Mar 2025 14:49:21 +0800 Lance Yang wrote: > > > This patch replaces 'struct mutex *blocker_mutex' with 'unsigned long > > blocker', as only one blocker is active at a time. > > > > The blocker filed can store both the lock addrees and the lock type, with > > LSB used to encode the type as Masami suggested, making it easier to extend > > the feature to cover other types of locks. > > > > Also, once the lock type is determined, we can directly extract the address > > and cast it to a lock pointer ;) > > > > ... > > > > --- a/include/linux/sched.h > > +++ b/include/linux/sched.h > > @@ -1218,7 +1218,7 @@ struct task_struct { > > #endif > > > > #ifdef CONFIG_DETECT_HUNG_TASK_BLOCKER > > - struct mutex *blocker_mutex; > > + unsigned long blocker; > > -ENOCOMMENT > Got it. Does the following change make sense and is it clear? diff --git a/include/linux/sched.h b/include/linux/sched.h index f27060dac499..27dad9aa99a0 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1218,6 +1218,10 @@ struct task_struct { #endif #ifdef CONFIG_DETECT_HUNG_TASK_BLOCKER + /* + * Encoded lock address causing task block (lower 2 bits = type from + * ). Accessed via hung_task_*() helpers. + */ unsigned long blocker; #endif --- Thanks, Lance