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b=l3OfO1zr+4AQtU5i3EXFDuZK9ABQGbrNJ7sYLgItekge5HMATapGwK4GvA2hApyyx I1Dwc5fjPTnR7lQ8IsGoQEOSkVk9tarUG8F0LRPaftZNYVwkVXH1vkitYZu1uRkghc BwJhkI8/s/Oaj0jLkQ0VJAS+aG/92A4BZLVDYGp629tGpDPcxLwyEAm2uL5Et74ZG5 Vl917h5pkpKHzBOJ/QsRYhpGNyzdkmyhG4GuXvcoYNOr4NXxbxmswyt1iFrp1uz6AL Nc2xaBGx98FhBywR1H/ovvXg3l7uduOuPMnLGyuxVgfg1ST8TAEE3sewS71C8y3Czu xEqzqzYldOavQ== From: Arnd Bergmann To: Andrew Morton , Johannes Weiner Cc: Arnd Bergmann , Kairui Song , Qi Zheng , Shakeel Butt , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , David Hildenbrand , Michal Hocko , Lorenzo Stoakes , Muchun Song , Baolin Wang , Davidlohr Bueso , Koichiro Den , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [PATCH] [v2] mm/vmscan: avoid false-positive -Wuninitialized warning Date: Tue, 14 Apr 2026 08:51:58 +0200 Message-Id: <20260414065206.3236176-1-arnd@kernel.org> X-Mailer: git-send-email 2.39.5 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Stat-Signature: tye98uxubptg1hhe511mwgdyupggi66z X-Rspamd-Queue-Id: 46CDD4000A X-Rspamd-Server: rspam09 X-HE-Tag: 1776149536-961309 X-HE-Meta: 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 L2dMDVBb x8gE2n1TjtCpEooMqn0SDL9ANIxd8UR08cOUQMZPMZMQE5FG50Wjr3VWpC+3w36OgcUrbnnspvCxFV0CuyfpMm257KtF1ZbcJ5TBEBDNpm7z9+nN5rUPhCUgu8UM2HJ569o/HEGj4uXMDReMxylRnrhMG+gIsJCUqhqFYtMp9F3MEWV5dggntazjsMwgIcUpOXGL/QYRx8lcG1UTIxfnWG5wzBlzUDqfobyyjCIiauxRK/ypYjp+0uTorl0X2aeNxA3xa Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Arnd Bergmann When the -fsanitize=bounds sanitizer is enabled, gcc-16 sometimes runs into a corner case in the read_ctrl_pos() pos function, where it sees possible undefined behavior from the 'tier' index overflowing, presumably in the case that this was called with a negative tier: In function 'get_tier_idx', inlined from 'isolate_folios' at mm/vmscan.c:4671:14: mm/vmscan.c: In function 'isolate_folios': mm/vmscan.c:4645:29: error: 'pv.refaulted' is used uninitialized [-Werror=uninitialized] Part of the problem seems to be that read_ctrl_pos() has unusual calling conventions since commit 37a260870f2c ("mm/mglru: rework type selection") where passing MAX_NR_TIERS makes it accumulate all tiers but passing a smaller positive number makes it read a single tier instead. Shut up the warning by adding a fake initialization to the two instances of this variable that can run into that corner case. Link: https://lore.kernel.org/all/CAJHvVcjtFW86o5FoQC8MMEXCHAC0FviggaQsd5EmiCHP+1fBpg@mail.gmail.com/ Signed-off-by: Arnd Bergmann --- v2: replace the earlier more invasive cleanup with a trivial workaround --- mm/vmscan.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index d3312c51f3f2..f829435d2807 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -4760,7 +4760,7 @@ static int scan_folios(unsigned long nr_to_scan, struct lruvec *lruvec, static int get_tier_idx(struct lruvec *lruvec, int type) { int tier; - struct ctrl_pos sp, pv; + struct ctrl_pos sp, pv = {}; /* * To leave a margin for fluctuations, use a larger gain factor (2:3). @@ -4779,7 +4779,7 @@ static int get_tier_idx(struct lruvec *lruvec, int type) static int get_type_to_scan(struct lruvec *lruvec, int swappiness) { - struct ctrl_pos sp, pv; + struct ctrl_pos sp, pv = {}; if (swappiness <= MIN_SWAPPINESS + 1) return LRU_GEN_FILE; -- 2.39.5