From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794046121; b=M4jC2uRrvPgKRg8b4WYnDNAJIQQAHXX0x7gXothX7rcf0ToRrqFhKtLI+XP/XEs0k8oe LJDiM8D1nF8LXD07sC3A1pfLExhwvqarQz0hg5FSGABhF+AR2AIHgpm77uazl+5O6VM3Y H3SYT5ux5yfuAQ3QGj7kGo8xpl5sbqUuxhx+9rueGFvB4jYGDUE6obWcxrKttGswkWrxC 6KekNyEP/Dtv+428I77LkioIWgQEq6gLA+R1mWB1TtUuKscm30Ctaa4xZL++5xoZ1pJqx s3ivH1P2/tEchyLK+8F+4/zEnyT3pVc/W82V9iZI1AHHuO15hNEKffiodF7tTTjBnyw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794046121; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=9P9JC2N5SVnSD1mOn8EgQe5yjcvVZOshqDaMuJEorxs=; b=YcrhW6cGTR5kpX0A2GL7v3zzUJKpNhfpvMjLHRf2v/6/pupqNXNIC4iUe+u2sI1SJA27 Xh/Do4xifN9UoDzn3K2tZoQKE0XsL40TArEHF7OTstkd0cDHpYAcSnpbYtxx6147kdFtC k9Hw14NgqEwQPnm4k2MsuBV0NQfJCefLSadiKtW03VaeEbmKrnO+N1goxcbKRrhclDDbg pRuqL1F7XANvB4sWUDXyN7DTEyosAENgkb3/HypkFlx5H2xYr3mvJcDk6/6pFNjYnmqX2 ZN8tT9Xi9WrvOAtWjBXEx4+ZRWs2f3ZQhvEw81c/e4P/YSDxyLPiIbeIWlpmPGZPJnA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=G44qzpCu; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id C2BDE606A326 for ; Sat, 7 Nov 2026 10:08:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=G44qzpCu Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6C7701F0089F; Sat, 7 Nov 2026 10:08:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794046120; bh=9P9JC2N5SVnSD1mOn8EgQe5yjcvVZOshqDaMuJEorxs=; h=From:To:Cc:Subject:Date; b=G44qzpCu53gp7IMxrJWxu2Gz1SoXbUkYEvoEGcIW9x/sJbZHCJVj34EfEsiCOrM6y gSaw+d0HW1/Qr120Ax7K0NkypdzaYC0pxU5bmNZ0+CChcRc07WmkDjrBHZW6q81Ach jorwk3ldcQF7rOBJSXk5baGZT3Z1fv5eghbDIkqwMOdTWeDqxQkGhDT25A6F8oO8Lb IGf/9+IImZzvbYBs7laBB+LmCRj9+3mRu0jdZsAk8M02+79f8fRKhxBSaG9MN/UHjr thowy4m9RLZpC2Vkfs63Thjl1VTcrq+iL6OStb0Bo/TTP1ARp2HfFIcEI3Nz7+gW/v sGygXsu6x5jcQ== From: Sasha Levin To: jiayuan.chen@linux.dev, akpm@linux-foundation.org, muchun.song@linux.dev, hannes@cmpxchg.org, mhocko@suse.com, chrisl@kernel.org, jack@suse.cz, axboe@kernel.dk, roman.gushchin@linux.dev, shakeel.butt@linux.dev, tj@kernel.org Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] mm/memcontrol: fix data-race on reading jiffies_64" failed to apply to 6.18-stable tree Date: Sat, 7 Nov 2026 05:08:38 -0500 Message-ID: <20261107050838-failed-6.18-c20cf1c3c8cd@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.18-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.18.y git checkout FETCH_HEAD git cherry-pick -x c20cf1c3c8cdd98618d6fcc794003a0e003ae858 # git commit -s git send-email --to '' --in-reply-to '20261107050838-failed-6.18-c20cf1c3c8cd@kernel.org' --subject-prefix 'PATCH 6.18.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From c20cf1c3c8cdd98618d6fcc794003a0e003ae858 Mon Sep 17 00:00:00 2001 From: Jiayuan Chen Date: Thu, 27 Aug 2026 10:54:56 +0800 Subject: [PATCH] mm/memcontrol: fix data-race on reading jiffies_64 KCSAN reported a data-race between tick_do_update_jiffies64() updating jiffies_64 and mem_cgroup_flush_stats_ratelimited() reading it directly. Unlike jiffies, jiffies_64 is not volatile, so raw reads are plain accesses and can even be torn on 32-bit. Use get_jiffies_64() instead, and fix the same pattern in mem_cgroup_flush_foreign(). Link: https://lore.kernel.org/20260827025457.116191-1-jiayuan.chen@linux.dev Fixes: 508bed884767 ("mm: memcg: change flush_next_time to flush_last_time") Fixes: 97b27821b485 ("writeback, memcg: Implement foreign dirty flushing") Signed-off-by: Jiayuan Chen Signed-off-by: Andrew Morton Reported-by: syzbot+ced4d9a8cadb5ef3adae@syzkaller.appspotmail.com Acked-by: Muchun Song Acked-by: Johannes Weiner Acked-by: Michal Hocko Cc: Chris Li Cc: Jan Kara Cc: Jens Axboe Cc: Roman Gushchin Cc: Shakeel Butt Cc: Tejun Heo Cc: --- mm/memcontrol.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 856a7d07586cc..d399710e9799a 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -757,7 +757,7 @@ static void __mem_cgroup_flush_stats(struct mem_cgroup *memcg, bool force) return; if (mem_cgroup_is_root(memcg)) - WRITE_ONCE(flush_last_time, jiffies_64); + WRITE_ONCE(flush_last_time, get_jiffies_64()); css_rstat_flush(&memcg->css); } @@ -785,7 +785,7 @@ void mem_cgroup_flush_stats(struct mem_cgroup *memcg) void mem_cgroup_flush_stats_ratelimited(struct mem_cgroup *memcg) { /* Only flush if the periodic flusher is one full cycle late */ - if (time_after64(jiffies_64, READ_ONCE(flush_last_time) + 2*FLUSH_TIME)) + if (time_after64(get_jiffies_64(), READ_ONCE(flush_last_time) + 2 * FLUSH_TIME)) mem_cgroup_flush_stats(memcg); } @@ -3946,7 +3946,7 @@ void mem_cgroup_flush_foreign(struct bdi_writeback *wb) { struct mem_cgroup *memcg = mem_cgroup_from_css(wb->memcg_css); unsigned long intv = msecs_to_jiffies(dirty_expire_interval * 10); - u64 now = jiffies_64; + u64 now = get_jiffies_64(); int i; for (i = 0; i < MEMCG_CGWB_FRN_CNT; i++) { -- 2.53.0