From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id E52ED286412 for ; Wed, 25 Feb 2026 05:53:26 +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=1771998808; cv=none; b=CUQiQywvO8jAT65OIb5PNZ5TegQpkj+TuYxlKb4kysB3xTdidPep9VM4a699olWgfsEWwA/04iIrOJEM5BBlA++LLg7D6WiziWmp+RxWXKbc5sXO8Ao4qiRlVGZBK9w4cJYgbZajRQ2m6q8Hbsd6YbUQ4psViTCjBnpwyP52JFE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771998808; c=relaxed/simple; bh=tCF7cbUYQxVKIc30Ftvy0Y9GGEqqOSP0DPok48hsQo0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=sDVtm01KQ9xD8bS6HRC9aDkxEH7R+ytoNBXngs81BN/SEppHAEG2C//+0Q2EdeU6rj1CUVAE95Qou/Sz/GTBsDeKGJO5MKpxsEraZ3hfQfF2gHTTh09/oGVqGVrCCtJbtpa6BdbAfwkC5uYqRier40kRVH/7HaaZB20bpVaZbgk= 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; 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 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 D7C0B165C; Tue, 24 Feb 2026 21:53:19 -0800 (PST) Received: from [10.163.172.18] (unknown [10.163.172.18]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A4F3D3F7BD; Tue, 24 Feb 2026 21:53:20 -0800 (PST) Message-ID: <72855b0c-5bf1-48dc-b4b8-a04f8ac34317@arm.com> Date: Wed, 25 Feb 2026 11:23:16 +0530 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] mm/cma: move put_page_testzero() out of VM_WARN_ON in cma_release() To: Zi Yan , Andrew Morton Cc: David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kefeng Wang , linux-mm@kvack.org, linux-kernel@vger.kernel.org, SeongJae Park , Ron Economos References: <20260225031231.2352011-1-ziy@nvidia.com> Content-Language: en-US From: Anshuman Khandual In-Reply-To: <20260225031231.2352011-1-ziy@nvidia.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 25/02/26 8:42 AM, Zi Yan wrote: > When CONFIG_DEBUG_VM is not set, VM_WARN_ON is a NOP. Putting any statement > with side effect inside it is incorrect. Collect all !put_page_testzero() > results and check the sum using WARN instead after the loop. It restores > the same check in free_contig_range() before commit > e0c1326779cc ("mm: page_alloc: add alloc_contig_frozen_{range,pages}()"), > the commit prior to the Fixes one. > > Fixes: 9bda131c6093 ("mm: cma: add cma_alloc_frozen{_compound}()") > Reported-by: Ron Economos > Closes: https://lore.kernel.org/all/1b17c38f-30d3-4bb4-a7e1-e74b19ada885@w6rz.net/ > Suggested-by: Kefeng Wang > Signed-off-by: Zi Yan > --- > From V2: > - Collect !put_page_testzero() to get the right result. > > From V1: > - Collect all put_page_testzero() results and do a single WARN after the > loop. > > mm/cma.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/mm/cma.c b/mm/cma.c > index 94b5da468a7d..15cc0ae76c8e 100644 > --- a/mm/cma.c > +++ b/mm/cma.c > @@ -1013,6 +1013,7 @@ bool cma_release(struct cma *cma, const struct page *pages, > unsigned long count) > { > struct cma_memrange *cmr; > + unsigned long ret = 0; > unsigned long i, pfn; > > cmr = find_cma_memrange(cma, pages, count); > @@ -1021,7 +1022,9 @@ bool cma_release(struct cma *cma, const struct page *pages, > > pfn = page_to_pfn(pages); > for (i = 0; i < count; i++, pfn++) > - VM_WARN_ON(!put_page_testzero(pfn_to_page(pfn))); > + ret += !put_page_testzero(pfn_to_page(pfn)); > + > + WARN(ret, "%lu pages are still in use!\n", ret); > > __cma_release_frozen(cma, cmr, pages, count); > Makes sense to make the above warning unconditional regardless of CONFIG_DEBUG_VM. Reviewed-by: Anshuman Khandual