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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: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 60E7940007 X-Stat-Signature: ew18ydcscfaw7c18bnjuz9pb3x5u3xcb X-Rspam-User: X-HE-Tag: 1777244613-884831 X-HE-Meta: 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 00YiS7GE Nxl+ihwDnfF7afETKqoUJGEgB2lsPuQTVpcvloTXeuWPnHPwIy5VBeOxK1rSricLrEYtnEgyWXYqJq9nCxx5HglZKMong2rPBhDq5MU9dnZuNXEyuJY14OcwbIjevmMaSENDRwP6ezcMDqz6ySlr55iDZIzJ4OrLIDca12EIhJEwdb7fhNO/Jtkm8dYeKsrEqLITIIPE3pHPUsRmGzjiuY3TSFItFC3249POpf0ixdXDBX5A3kviyq8BXlWs/5UrHrIxjd5cCv5ZjEKYGfB8N0hMl63VijmhlLuIItlOic/hqUwzXpSWKW3UUoLcTSIQ6KwFeWLNycUIEkQEafDnSsKRCWA== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: [...] > 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