From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 82E6822B5AD for ; Wed, 25 Feb 2026 02:54:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771988083; cv=none; b=S+wS0tOHoZNAz8mDsh1ITtSfbNLvurTuf7JfilZH3nKNfqf0SJbWW4pSob3h8YAxEGdcPCpObV1AoQzynGSYb63z1bgYy3McY5f3ao7CL826jEO9u0cBYxLGex/KfwWlbrBCdU/9vZmqqODGOrtJpUwPAidSFnJjKdED57G5ApA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771988083; c=relaxed/simple; bh=sv0BlK/PbJISeFWRNtuvB50+SpWmS9eaRA5oaLiZUfc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=TvLGdqcFGavjPccELSxr1LlEmDD0zldu8MKp7WGBeDaynq2hJ3Ban3inDp58pKeY1yx1o+UTRWVRg/vqa+q0bdnIkj9SQplNOrJVm0eDcxeXFJ3Q0X0UsQeequKqQ69/2DBaLfBnMrc/xsC470aspplwzTewLT0AwC1X6VkrQqk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dVnbsjQH; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dVnbsjQH" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A6E1AC116D0; Wed, 25 Feb 2026 02:54:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1771988083; bh=sv0BlK/PbJISeFWRNtuvB50+SpWmS9eaRA5oaLiZUfc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dVnbsjQHy6FVcw4vQWo0DIfbZItECN3MHkQSIx6PKyGIuREBKGeAG24vZXXFE+Tzm vS7MULKaeu2m3PB2WKqeHPeJ4qtgG6fBbvMQkH2qVJm4yqyx3aEbk80si3oTB0OEZT +NFEq7/yAhuCVLfZW25e02xHd1yDcJwqU9a57k5dgug6N9ZnEGkKCoEY4OZK0rYfHF 1ywjE9nroeVLAPRNWHFd+aN7Qb1fhH9car1NpKJyb6HYDtAZol04esfFTiUD3/u3Dt 7N16SWqLMkcvf2038aR6t1bYoRJQTq/IQ31guy7C8HgdMZG1YelCtg6cODMYKeMlEt bH4cclVgLGB+g== From: SeongJae Park To: Zi Yan Cc: SeongJae Park , Andrew Morton , 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, Ron Economos Subject: Re: [PATCH v2] mm/cma: move put_page_testzero() out of VM_WARN_ON in cma_release() Date: Tue, 24 Feb 2026 18:54:40 -0800 Message-ID: <20260225025440.63897-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260225022853.2347732-1-ziy@nvidia.com> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Tue, 24 Feb 2026 21:28:52 -0500 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. > > 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 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..ea540d3f473c 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)); So, 'ret' will be incremented when put_page_testzero() returns 'true', right? Shouldn't 'ret' be inceremented only when put_page_testzero() returns 'false'? > + > + WARN(ret, "%lu pages are still in use!\n", ret); This will trigger the warning even if CONFIG_DEBUG_VM is unset. I'm fine with the changed behavior, but I'm curious if that is the real intention of this revision. Thanks, SJ [...]