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Mon, 10 Feb 2025 10:22:34 +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 BAv3MmrTqWcVSgAAD6G6ig (envelope-from ); Mon, 10 Feb 2025 10:22:34 +0000 Date: Mon, 10 Feb 2025 11:22:18 +0100 From: Oscar Salvador To: Frank van der Linden Cc: akpm@linux-foundation.org, muchun.song@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, yuzhao@google.com, usamaarif642@gmail.com, joao.m.martins@oracle.com, roman.gushchin@linux.dev Subject: Re: [PATCH v3 01/28] mm/cma: export total and free number of pages for CMA areas Message-ID: References: <20250206185109.1210657-1-fvdl@google.com> <20250206185109.1210657-2-fvdl@google.com> 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: <20250206185109.1210657-2-fvdl@google.com> X-Rspamd-Queue-Id: 7A2B11F38F X-Spam-Level: X-Spamd-Result: default: False [-4.51 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; RCPT_COUNT_SEVEN(0.00)[9]; MISSING_XM_UA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_TLS_ALL(0.00)[]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; FUZZY_BLOCKED(0.00)[rspamd.com]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[linux-foundation.org,linux.dev,kvack.org,vger.kernel.org,google.com,gmail.com,oracle.com]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:dkim,suse.de:email,imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action X-Spam-Score: -4.51 X-Spam-Flag: NO On Thu, Feb 06, 2025 at 06:50:41PM +0000, Frank van der Linden wrote: > In addition to the number of allocations and releases, system > management software may like to be aware of the size of CMA > areas, and how many pages are available in it. This information > is currently not available, so export it in total_page and > available_pages, respectively. > > The name 'available_pages' was picked over 'free_pages' because > 'free' implies that the pages are unused. But they might not > be, they just haven't been used by cma_alloc > > The number of available pages is tracked regardless of > CONFIG_CMA_SYSFS, allowing for a few minor shortcuts in > the code, avoiding bitmap operations. > > Signed-off-by: Frank van der Linden LGTM, nit below Reviewed-by: Oscar Salvador > --- ... > @@ -444,6 +445,14 @@ static struct page *__cma_alloc(struct cma *cma, unsigned long count, > > for (;;) { > spin_lock_irq(&cma->lock); > + /* > + * If the request is larger than the available number > + * of pages, stop right away. > + */ > + if (count > cma->available_count) { > + spin_unlock_irq(&cma->lock); > + break; > + } > bitmap_no = bitmap_find_next_zero_area_off(cma->bitmap, > bitmap_maxno, start, bitmap_count, mask, > offset); > @@ -452,6 +461,7 @@ static struct page *__cma_alloc(struct cma *cma, unsigned long count, > break; > } > bitmap_set(cma->bitmap, bitmap_no, bitmap_count); > + cma->available_count -= count; I wonder whether we should have a cma_bitmat_set, so available_count would be touched in there. -- Oscar Salvador SUSE Labs