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 989B12459CF; Sun, 26 Apr 2026 23:03:32 +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=1777244612; cv=none; b=UfxxWrRRtp4FdXjTFdoGACCYvKXBo+s2GdeV9P/TLJuLXuWXtxyZRPudtkF2n6M3ZUq4xzCnWBo4AIj+SnxlyTjnyVRaiOWMYiHehZAmaAxIRZ3mGWFgPDz3Kby/tzd7ofPvuMX6CTJU0wZ2treqL2qoyBBSUmXRbI07T3p/pAA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777244612; c=relaxed/simple; bh=Pssmh29rua0G3vOV364oBo0PTZnVdOappMtfzOGeM9o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=DNmuuqRk2MvNDvCS5TbE7nPGEb3TLH/+3BsjsikTaAB6cK8BUszYqYrgTUjsfU/KIcSCS/O59LvJyd3CvF2DDLtDdJIREMJ8zpaO7ftOCj59DSVi0FmbdR2kPDhIVF8S2dc7aYRigfStXMHaq6BjBbcl6/L/aJBjARAbL6FzyF4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YlJWjHgt; 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="YlJWjHgt" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C3CB1C2BCAF; Sun, 26 Apr 2026 23:03:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777244612; bh=Pssmh29rua0G3vOV364oBo0PTZnVdOappMtfzOGeM9o=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YlJWjHgty3V7f+TFjCTTSoMO9eVq3QxibsfL3USNcWt+m+mQAw0V8oHOQzF0NPdmx E2JVEskMw3+0fcgpc/QzkABNkw7Oc7NFMr9C3iSy25Mb2/V1YLUIvv3NlhnEJlNQWA zDfMnJxeNCWoPFUfrmoF6v/dyU7TuuXs4Abuq6u+GH8gtF1qivbcte7fnARGBTkAQd Y5YxBmUkfsRFqdtGX3hLjg5ED4NV8p0RinkPlujKnO3XOJf7G6kmudkV9GuvdR20Va 1XlX14eFJWaUwyp4+9Ib6VuwoXDZPyevcvENziMot7yITaYyKgpl34QUguPdS3oqvI HWV0rdIX11X3w== From: SeongJae Park To: Ravi Jonnalagadda Cc: SeongJae Park , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, akpm@linux-foundation.org, corbet@lwn.net, bijan311@gmail.com, ajayjoshi@micron.com, honggyu.kim@sk.com, yunjeong.mun@sk.com Subject: Re: [PATCH v9] mm/damon: add node_eligible_mem_bp goal metric Date: Sun, 26 Apr 2026 16:03:21 -0700 Message-ID: <20260426230322.106206-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260426213859.1835-1-ravis.opensrc@gmail.com> References: Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit [...] > Changes since v8: > ================= > https://lore.kernel.org/linux-mm/20260426003245.2687-1-ravis.opensrc@gmail.com/ > > - Removed unnecessary casts in mult_frac() call to fix potential > divide-by-zero on 32-bit PAE systems (Sashiko/SJ review) > - Kept original parameter name 'ctx' in damos_set_effective_quota() > to avoid unnecessary diff (SJ review) [...] > +static unsigned long damos_get_node_eligible_mem_bp(struct damon_ctx *c, > + struct damos *s, int nid) > +{ > + phys_addr_t total_eligible = 0; > + phys_addr_t node_eligible; > + > + if (c->ops.id != DAMON_OPS_PADDR) > + return 0; > + > + if (nid < 0 || nid >= MAX_NUMNODES || !node_online(nid)) > + return 0; > + > + node_eligible = damos_calc_eligible_bytes(c, s, nid, &total_eligible); > + > + if (!total_eligible) > + return 0; > + > + return mult_frac(node_eligible, 10000, total_eligible); > +} Sashiko found [1] this can cause __udivdi3 linking issue on 32bit machine with CONFIG_PHYS_ADDR_T_64BIT. Seems that is correct to me. I believe below attaching fixup can fix it? Ravi, if my fixup looks good to you, could you please post another version (say, v9.1) for another Sashiko review round? [1] https://lore.kernel.org/20260426220409.95B26C2BCAF@smtp.kernel.org Thanks, SJ [...] === >8 === >From 828ddfdfa3a996efc4620919a3cc77d55088c466 Mon Sep 17 00:00:00 2001 From: SeongJae Park Date: Sun, 26 Apr 2026 15:54:48 -0700 Subject: [PATCH] mm/damon/core: avoid __udivdi3 linking issue On 32bit machines having PHYS_ADDR_T_64BIT, mult_frac() with phys_addr_t will cause __udivdi3 linking issue. Cast values to 'unsigned long' before calling mult_frac(). This could cause divide-by-zero if the denominator becomes zero by casting. Avoid it by checking the zero case with the casted value. Signed-off-by: SeongJae Park --- mm/damon/core.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/mm/damon/core.c b/mm/damon/core.c index 0ea747d487465..aec43314fc4a9 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -2921,10 +2921,11 @@ static unsigned long damos_get_node_eligible_mem_bp(struct damon_ctx *c, node_eligible = damos_calc_eligible_bytes(c, s, nid, &total_eligible); - if (!total_eligible) + if (!(unsigned long)total_eligible) return 0; - return mult_frac(node_eligible, 10000, total_eligible); + return mult_frac((unsigned long)node_eligible, 10000, + (unsigned long)total_eligible); } #else /* CONFIG_DAMON_PADDR */ static unsigned long damos_get_node_eligible_mem_bp(struct damon_ctx *c, -- 2.47.3