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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> 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-Action: no action X-Rspamd-Queue-Id: 1C79D140006 X-Stat-Signature: w9wa9gk6caz364skxr3ygpq3faqwgwww X-Rspam-User: X-Rspamd-Server: rspam01 X-HE-Tag: 1739182956-96706 X-HE-Meta: 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 M79iABMQ g7wmFuPE4/YIKPiiLviDZnqLLtv4D/poRQvnxtzx/gdBTIXXLPLwX1TY8LXZmrsqgdlSvP0au0edWopC2bl3JR6PSkj3b/M7WAtVOZdnbGCRS/bCe0nK0EqEklpDnHGLkqynnx05ycn0XlParUnibnQvXwxTNZ0EUOuO2oe+ws3VMy4DzAb2dKEpxYJOn5JWYJ5nTgdonmK5KKpz9b57eyb9SOgyb4HiKqp7P1Lv0gpmfpDR2kNjvGT9G4Wvm+HyBZcyKIHPhz7RT73o6FKRofxXevmzcYmSY2kp75q4QvjUev9l+QtzeWATFdYnwk2/Va4XO X-Bogosity: Ham, tests=bogofilter, spamicity=0.000006, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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