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Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1qXwEa-0081su-Uu; Mon, 21 Aug 2023 04:09:45 +0000 Date: Mon, 21 Aug 2023 05:09:44 +0100 From: Matthew Wilcox To: Byungchul Park Cc: linux-kernel@vger.kernel.org, kernel_team@skhynix.com, torvalds@linux-foundation.org, damien.lemoal@opensource.wdc.com, linux-ide@vger.kernel.org, adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, mingo@redhat.com, peterz@infradead.org, will@kernel.org, tglx@linutronix.de, rostedt@goodmis.org, joel@joelfernandes.org, sashal@kernel.org, daniel.vetter@ffwll.ch, duyuyang@gmail.com, johannes.berg@intel.com, tj@kernel.org, tytso@mit.edu, david@fromorbit.com, amir73il@gmail.com, gregkh@linuxfoundation.org, kernel-team@lge.com, linux-mm@kvack.org, akpm@linux-foundation.org, mhocko@kernel.org, minchan@kernel.org, hannes@cmpxchg.org, vdavydov.dev@gmail.com, sj@kernel.org, jglisse@redhat.com, dennis@kernel.org, cl@linux.com, penberg@kernel.org, rientjes@google.com, vbabka@suse.cz, ngupta@vflare.org, linux-block@vger.kernel.org, josef@toxicpanda.com, linux-fsdevel@vger.kernel.org, viro@zeniv.linux.org.uk, jack@suse.cz, jlayton@kernel.org, dan.j.williams@intel.com, hch@infradead.org, djwong@kernel.org, dri-devel@lists.freedesktop.org, rodrigosiqueiramelo@gmail.com, melissa.srw@gmail.com, hamohammed.sa@gmail.com, 42.hyeyoo@gmail.com, chris.p.wilson@intel.com, gwan-gyeong.mun@intel.com, max.byungchul.park@gmail.com, boqun.feng@gmail.com, longman@redhat.com, hdanton@sina.com, her0gyugyu@gmail.com Subject: Re: [RESEND PATCH v10 08/25] dept: Apply sdt_might_sleep_{start,end}() to PG_{locked,writeback} wait Message-ID: References: <20230821034637.34630-1-byungchul@sk.com> <20230821034637.34630-9-byungchul@sk.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230821034637.34630-9-byungchul@sk.com> X-Rspamd-Queue-Id: 0CD5C18001A X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: knoz37xyy44qs7sj6xb5d7gid8kjbc4r X-HE-Tag: 1692591068-330051 X-HE-Meta: U2FsdGVkX1/gFSl++kRw4BYNwOi6LVxcKrRwE/Hw7YQjgtgIN3IMWalMWXEgx0Ynl14jHa/rMWMdQr8DSox99R4sZKWvRhH9Y0u4lc93qZMDIiwlGueYQIdirIpQ4kCLA/GUU6lWnPg1dXSv2Z0Ku5gOuujGHjESnkBO5xXYAt+6zNecwaEhzzO11ls/Fn89t4mCYhtcW8m8guIGHYqzI/8F/pwtImLrrPp6kVJdikadPAFzguEJ80u2fXPqAU4LzXLeVEpYqreib+mRSiuBwYen75WuUh0H3zsjRoiuid8jixd2i8ss1qCjEGBZ+JRRdJm/M76skT4KPnUdUUtGvVJiCLcnhhsVjJsTQBSRZFl/YjryjOKf/M/onDx/cN7YjanYumJjXRRHwn4t5Vnv6a1gSLMTmmly/diXdI3uC60JbkYUQzsdnwnOfGUdXkdu0FI9J+Q3jLv6C3JgRzYkYYIxvmEB6Eqt2iCMV5ke099YxQ3bCmR6fAnb2Zv96lN7eo27JDibAJxtghCUxatyMPLHwyXsc52hKhgNH8N5RLTCgUtGw92z27LbATUSlVxzdkz30j8CxXVV9Mm9yp3UlvVIjIX9J8Po4gyeIuE3To1ontg18T/geVU3FHFwhLj3ktzAwoGB4CLyTKsZDHWzuJiOEnw4KAkeedzDa5DQyt1GQFubAV1XFfZMmuLnZAMf/bAHhwh8tI7llGVRlbajCbLbPOJfU3at+aH0buRcXV4ZGJrbWsB07BxKyH3dqaf1fpO14O+A3mZzZJMyjj8j0NXoorB5W7fBXyPQ8CwUo6Ki2JV10iAigQob4K6b98taiY7r3j2iDzo4PAs3Enp/ZlkweDOBEYuVByT9UpjIwqCVR7oPTQ5fCxS6hLRsFgRZAUs/pagiIBbrB1i4j16c7N1a79t8eNOPbuZkpmKyuTHHyYUuqfBJnDZhZMxmVnld6BztFvhI48yTR9zAtJf ZhGvhsjM bWKd28DYU5oY76K5tfY4Me4OaNTwMXkGb9SNfVKGOtpd+LDGuyMOtZLdm+nzq9/3D97DuSZUk2Hz/UoL3/MG3TJSUvvBv1gTdkLJFJGA0Tn1/HIJJ1qV1XoUU4OqIEUoIo6ftY0KquGL/SdIO7vlmzwafDMm5mRedJNhd9YpVbAg8cysPmbr+ysqzEjDnfIJsIH41BeUomnyfErkhehS1Ma74wYssU7rW8rByQJ5H9sgGw8yr+LV9c3FYtIRW+BssloMT 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: On Mon, Aug 21, 2023 at 12:46:20PM +0900, Byungchul Park wrote: > @@ -1219,6 +1220,9 @@ static inline bool folio_trylock_flag(struct folio *folio, int bit_nr, > /* How many times do we accept lock stealing from under a waiter? */ > int sysctl_page_lock_unfairness = 5; > > +static struct dept_map __maybe_unused PG_locked_map = DEPT_MAP_INITIALIZER(PG_locked_map, NULL); > +static struct dept_map __maybe_unused PG_writeback_map = DEPT_MAP_INITIALIZER(PG_writeback_map, NULL); Hmm, why are these "maybe unused"? *digs*. Ah. Because sdt_might_sleep_start() becomes a no-op macro if DEPT is disabled. OK, the right way to handle this is #ifdef CONFIG_DEPT #define DEPT_MAP(name) static struct dept_map name = \ DEPT_MAP_INITIALIZER(name, NULL) #else #define DEPT_MAP(name) /* */ #endif And now DEPT takes up no space if disabled. /* */; is a somewhat unusual thing to see, but since this must work at top level, we can't use "do { } while (0)" like we usually do. Given where else this is likely to be used, i don't think it's going to be a problem ...