From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9375FFD45FF for ; Thu, 26 Feb 2026 01:33:03 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F00026B0088; Wed, 25 Feb 2026 20:33:02 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EDE3B6B0099; Wed, 25 Feb 2026 20:33:02 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E14516B009B; Wed, 25 Feb 2026 20:33:02 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id CE15D6B0088 for ; Wed, 25 Feb 2026 20:33:02 -0500 (EST) Received: from smtpin08.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 67FE51C5D3 for ; Thu, 26 Feb 2026 01:33:02 +0000 (UTC) X-FDA: 84484884204.08.B22CC26 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf24.hostedemail.com (Postfix) with ESMTP id CA395180006 for ; Thu, 26 Feb 2026 01:33:00 +0000 (UTC) Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=jYkt5C4P; spf=pass (imf24.hostedemail.com: domain of sj@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1772069580; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=a6EGQLiMGLNgLTwJzR9ZXHxtyEjIbgzNuXEIsz3biw0=; b=qoHRtuvIgiTktPs3/taaZAGdCiBkV7ZOP9WPu8AbtAlv52HMMD1c9ObpMu2QRmvTHSLKf+ TCZRIx+qV1HkUHa1KHKQHDUsXGni2TBr/phZL2dp+im6pxKGDkM5lTEfYMf+kznRu4IltE 7gUz/Qg37cuNjvQKk4otiZSYT152USM= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1772069580; a=rsa-sha256; cv=none; b=qrYfiNRPwBjEhT+HjCEVPkR73MRTpxlIziVxWqSpIJ2kvbAPmOLGq9/zmpxD4PZlXJosg9 0zw+EH0WmtzG/kEfF2Vs8B+h1GPGh3hlm4yDnRuQUpDcguSIT6R9pZUiuT8RIlauyQvua7 VaTn+qTUL6amkR/LvAYL9l+SiujlIyU= ARC-Authentication-Results: i=1; imf24.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=jYkt5C4P; spf=pass (imf24.hostedemail.com: domain of sj@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=sj@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 47BF360053; Thu, 26 Feb 2026 01:33:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7AB1EC116D0; Thu, 26 Feb 2026 01:32:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772069580; bh=jz5yjUjM/f+IZwWRIgyYptE1sl+VBHPa3luymxuES4E=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=jYkt5C4Pb2PTBmn20lPNS6ETyWWb4ivEIHjhGZl4xP1EcLCSnVaSadSTPdl4n8Zg0 RSsHdOYrMQRtOnMrsw/EDzN2XimpO5klwpSVhT/30jZs1eH9wjd673GwAhTOPUz0LD pQwiRxXp2CntgV3ii5HkCXyx9X/r9NGG2qB3iEvzvsCxohgIN13gk7ytRXtyb43x6f lJpMDxjVyTTI5fGKRL+OSZk9F2t6rQccbWLmOPPor3YHP4gRkeeaBpKJKW/cpPGupW a3JhsUJPbRh3ewmE8lzGwv6EBA+mx9kq129CMQs98jvs99dtmmTFWhwAaIEpjrSSpU AqJ60K8UAX7BA== 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: Wed, 25 Feb 2026 17:32:57 -0800 Message-ID: <20260226013258.8490-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <7AAE3B00-627F-4F40-A383-7F5FDCBAC8F5@nvidia.com> References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: wgeh7sj3x1mg45du8tt5emdf36hxygwi X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: CA395180006 X-HE-Tag: 1772069580-691020 X-HE-Meta: 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 j9yan+Vj pNaP5khVQcaHg1vjMpYZWaFUEO3aldDxvm1ZWBgrh62B7TM0eAl1fEougaVbYb0/ds8jFmmdCDY9b1RCJiRVk8fXy0BogaYUa1WCojWrRnorNiNH+8v37B8T+afB7nA9VJdgxEM2ygrPSE7Ba00ck+d4OK1VMvQw30a1/apXHoBwoAhROUkF6pph+wIBOpeUZDAJkvk3YW4DtVhctDbuhzZqVhIYwrzBq9XlotJ+SE/82Rir82ORhs4SnOC4JAEYdZV8FG4gWWvg8w6PU12FfA0Brhg0dzb9fMQpu3KCpX6iNTM4FD08JHHVBq9nVQBYaSIf1BUqal6OwHmulehyDmhzzOIY9Y7dZjXZzd1Pr/ACcR0AFhqp4fv/Fb1P3ya+xnG4rKC4jEMhSS0+Y+FMpOUc+cPQKd4uKqPdASTIVsyQ0OF/u7ViqQuDl6C5O2KQCVH3q Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, 24 Feb 2026 22:04:15 -0500 Zi Yan wrote: > On 24 Feb 2026, at 21:54, SeongJae Park wrote: > > > 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'? > > Good catch. Let me fix it. Thanks. > > > > >> + > >> + 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. > > It was in free_contig_range()[1], which was called by cma_release() before. Makes sense, thank you for clarifying, Zi :) > > [1] https://elixir.bootlin.com/linux/v6.19/source/mm/page_alloc.c#L7238 Thanks, SJ [...]