From nobody Wed Apr 1 23:29:50 2026 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id B87C93E1226; Wed, 1 Apr 2026 10:16:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775038614; cv=none; b=ELVrwUZso3KYT0nC/agk6TzizgHETNS5xZYRlg7hLdLJdwyFmYoEeulm42Wv8qrB9ZHm0SIABVvMUPzsnnqOyH66D/dkd1ysyk4aNBPWY6KBVLUpNEGyhcHwElRBpUMUpaA5HR7bcdlaXlRsoOBVyxqfA3EFR+9YMOfyvLzXS24= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775038614; c=relaxed/simple; bh=JcWyvthdavWgIpUnVyB9xCucQ0sGFiNAMiRuaQriu5M=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=JxcPZRAjhUnr5zMVHoVhIWpXxONIOhX0wrk1rxX1GUDNwHNv670FFrzw3urJn2+cH1BsmOx/4UPg+6vze7RbfGkQkFHKHAPS271LyHcZQ6Ekco3oOC6r1nyN7ozrVEn7joUXGvgRdhR+MlwZCBURcWKFnZpVSMI19r0iJGvuvPE= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b=cjkIcEY8; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=arm.com header.i=@arm.com header.b="cjkIcEY8" Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 717A1288E; Wed, 1 Apr 2026 03:16:46 -0700 (PDT) Received: from e142334-100.cambridge.arm.com (e142334-100.cambridge.arm.com [10.1.194.63]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id C58B53F915; Wed, 1 Apr 2026 03:16:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=arm.com; s=foss; t=1775038612; bh=JcWyvthdavWgIpUnVyB9xCucQ0sGFiNAMiRuaQriu5M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cjkIcEY80aU0nc9DrAtDlvemrJtisTQdhIxgWMFO1i/GPAqlMUVVF7+CKMUF6t6TW v99mrEtPzOzw1dH45iLxm/mLfjCJ4BX5IMVlQ9xHGpkyVSThL1T9NToQP08WzmdhV9 0l61JB0mohQn7lUlkZYLNkyrCjRsyn9bQ430Y2sU= From: Muhammad Usama Anjum To: Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Uladzislau Rezki , Nick Terrell , David Sterba , Vishal Moola , linux-mm@kvack.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, Ryan.Roberts@arm.com, david.hildenbrand@arm.com Cc: Muhammad Usama Anjum Subject: [PATCH v6 3/3] mm/page_alloc: Optimize __free_contig_frozen_range() Date: Wed, 1 Apr 2026 11:16:21 +0100 Message-ID: <20260401101634.2868165-4-usama.anjum@arm.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260401101634.2868165-1-usama.anjum@arm.com> References: <20260401101634.2868165-1-usama.anjum@arm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Apply the same batch-freeing optimization from free_contig_range() to the frozen page path. The previous __free_contig_frozen_range() freed each order-0 page individually via free_frozen_pages(), which is slow for the same reason the old free_contig_range() was: each page goes to the order-0 pcp list rather than being coalesced into higher-order blocks. Rewrite __free_contig_frozen_range() to call free_pages_prepare() for each order-0 page, then batch the prepared pages into the largest possible power-of-2 aligned chunks via free_prepared_contig_range(). If free_pages_prepare() fails (e.g. HWPoison, bad page) the page is deliberately not freed; it should not be returned to the allocator. I've tested CMA through debugfs. The test allocates 16384 pages per allocation for several iterations. There is 3.5x improvement. Before: 1406 usec per iteration After: 402 usec per iteration Before: 70.89% 0.69% cma [kernel.kallsyms] [.] free_cont= ig_frozen_range | |--70.20%--free_contig_frozen_range | | | |--46.41%--__free_frozen_pages | | | | | --36.18%--free_frozen_page_commit | | | | | --29.63%--_raw_spin_unlock_ir= qrestore | | | |--8.76%--_raw_spin_trylock | | | |--7.03%--__preempt_count_dec_and_test | | | |--4.57%--_raw_spin_unlock | | | |--1.96%--__get_pfnblock_flags_mask.isra.0 | | | --1.15%--free_frozen_page_commit | --0.69%--el0t_64_sync After: 23.57% 0.00% cma [kernel.kallsyms] [.] free_cont= ig_frozen_range | ---free_contig_frozen_range | |--20.45%--__free_contig_frozen_range | | | |--17.77%--free_pages_prepare | | | --0.72%--free_prepared_contig_range | | | --0.55%--__free_frozen_pages | --3.12%--free_pages_prepare Acked-by: David Hildenbrand (Arm) Acked-by: Vlastimil Babka (SUSE) Reviewed-by: Zi Yan Suggested-by: Zi Yan Signed-off-by: Muhammad Usama Anjum --- Changes since v4: - Use /* */ style comment with boolean variable Changes since v3: - Use newly introduced __free_contig_range_common() as the pattern was very similar to __free_contig_range() Changes since v2: - Rework the loop to check for memory sections just like __free_contig_rang= e() - Didn't add reviewed-by tags because of rework --- mm/page_alloc.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 6568af69b5cdb..dec72cedcf674 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7054,8 +7054,7 @@ static int __alloc_contig_verify_gfp_mask(gfp_t gfp_m= ask, gfp_t *gfp_cc_mask) =20 static void __free_contig_frozen_range(unsigned long pfn, unsigned long nr= _pages) { - for (; nr_pages--; pfn++) - free_frozen_pages(pfn_to_page(pfn), 0); + __free_contig_range_common(pfn, nr_pages, /* is_frozen=3D */ true); } =20 /** --=20 2.47.3