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Fri, 9 Feb 2024 21:37:57 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id myfxIzWbxmWqaQAAD6G6ig (envelope-from ); Fri, 09 Feb 2024 21:37:57 +0000 Date: Fri, 9 Feb 2024 22:39:04 +0100 From: Oscar Salvador To: Marco Elver Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michal Hocko , Vlastimil Babka , Andrey Konovalov , Alexander Potapenko Subject: Re: [PATCH v7 2/4] mm,page_owner: Implement the tracking of the stacks count Message-ID: References: <20240208234539.19113-1-osalvador@suse.de> <20240208234539.19113-3-osalvador@suse.de> 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=us-ascii Content-Disposition: inline In-Reply-To: Authentication-Results: smtp-out1.suse.de; dkim=pass header.d=suse.de header.s=susede2_rsa header.b="BHiJ/fyF"; dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b="0WV/mw3F" X-Spamd-Result: default: False [-1.81 / 50.00]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MIME_GOOD(-0.10)[text/plain]; RCVD_DKIM_ARC_DNSWL_HI(-1.00)[]; DNSWL_BLOCKED(0.00)[2a07:de40:b281:106:10:150:64:167:received]; RCVD_COUNT_THREE(0.00)[3]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; DKIM_TRACE(0.00)[suse.de:+]; MX_GOOD(-0.01)[]; RCPT_COUNT_SEVEN(0.00)[8]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:dkim]; FUZZY_BLOCKED(0.00)[rspamd.com]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; FREEMAIL_CC(0.00)[linux-foundation.org,vger.kernel.org,kvack.org,suse.com,suse.cz,gmail.com,google.com]; RCVD_TLS_ALL(0.00)[]; RCVD_IN_DNSWL_HI(-0.50)[2a07:de40:b281:104:10:150:64:97:from] X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Rspamd-Queue-Id: 2A46F21CDF X-Spam-Level: X-Spam-Score: -1.81 X-Spam-Flag: NO On Fri, Feb 09, 2024 at 08:45:00AM +0100, Marco Elver wrote: > > +/** > > + * stack_depo_get_stack - Get a pointer to a stack struct > > Typo: "depo" -> depot > > I would also write "stack_record struct", because "stack struct" does not exist. Fixed. > > + * @handle: Stack depot handle > > + * > > + * Return: Returns a pointer to a stack struct > > + */ > > +struct stack_record *stack_depot_get_stack(depot_stack_handle_t handle); > > I don't know what other usecases there are for this, but I'd want to > make make sure we give users a big hint to avoid unnecessary uses of > this function. > > Perhaps we also want to mark it as somewhat internal, e.g. by > prefixing it with __. So I'd call it __stack_depot_get_stack_record(). Yes, I went with __stack_depot_get_stack_record(), and I updated its doc in stackdepot.h, mentioning that is only for internal purposes. > > +static void inc_stack_record_count(depot_stack_handle_t handle) > > +{ > > + struct stack_record *stack = stack_depot_get_stack(handle); > > + > > + if (stack) > > + refcount_inc(&stack->count); > > +} > > In the latest stackdepot version in -next, the count is initialized to > REFCOUNT_SATURATED to warn if a non-refcounted entry is suddenly used > as a refcounted one. In your case this is intentional and there is no > risk that the entry will be evicted, so that's ok. But you need to set > the refcount to 1 somewhere here on the initial stack_depot_save(). Well, I went with something like: static void inc_stack_record_count(depot_stack_handle_t handle) { struct stack_record *stack = __stack_depot_get_stack_record(handle); if (stack) { /* * New stack_records that do not use STACK_DEPOT_FLAG_GET start * with REFCOUNT_SATURATED to catch spurious increments of their * refcount. * Since we do not use STACK_DEPOT_FLAG_{GET,PUT} API, let us * set a refcount of 1 ourselves. */ if (refcount_read(&stack->count) == REFCOUNT_SATURATED) refcount_set(&stack->count, 1); refcount_inc(&stack->count); } } -- Oscar Salvador SUSE Labs