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 448E41DDC2B for ; Sun, 3 May 2026 00:40:18 +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=1777768818; cv=none; b=WQrQb6RX4EH54mE8et4pD74aZJadmyobJl/XIsXv6tM7jDypIwxgcZwG4Tb4qnkqNm5UfgE8bZ5Xpj0IbvV9MTraerRu0kPoqPgSpmKBUX1Rc9YsrM3UGe9yMtij1danGCW3wLcJGnYdfvbWvfI1Gi+ZOSUFLPDavqxwdw5uNU8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777768818; c=relaxed/simple; bh=JoNXbzQleeKxATWN9I1/FYrLrtu5V/njSfOAh2mK6Ks=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QlerSVHKXfEdNT9urXrx2r35tMqPiBxlYyPrh1X//YvhDE1NJANP84kwaOwaDSDjQzbSay0kS03AOqHljyG8UEOcXwJ/JVe+w7yD9YFj10l7OrYk9IVINk2VawywSCeS5dz3JO4KZv5Y51KD12mqx7AAeY5C03QDtL7XTpmNbAY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Y+z6ZfVs; 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="Y+z6ZfVs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 637FCC2BCB8; Sun, 3 May 2026 00:40:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777768817; bh=JoNXbzQleeKxATWN9I1/FYrLrtu5V/njSfOAh2mK6Ks=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Y+z6ZfVsoWYMixaIZfCg2vZV0wqITVpB0aVegXdNxBE67DbyvxCgtVrg2H3d0tslc TFD1bdbRceYD48kIxJ+FTAb9sFeDAgjhy2mrcg+NotV/lEMRTbbjlrfMEMt6mdMt2G 6gyVF5G71WE+f71jSsgMQZEsse9PhGXP/5TpgZJSgetWTwgZkU/6+I6iw0DxFb9Jfy FFdfZxBsrvRX8iLf7pKqW/3D9UuWcyPBiTE/s1R6OEkQvjJitdJRoGSSEFu2hZHl6I NN1Tb6xDMQgRo9ymneC4WvnLu8ZJyC86eo28x+ET2TqRNhpe31zQS3oEIKWPpkACJa YM6Yj7NV2jD0A== From: Sasha Levin To: stable@vger.kernel.org Cc: Joseph Salisbury , "Peter Zijlstra (Intel)" , Sasha Levin Subject: [PATCH 5.10.y] sched: Use u64 for bandwidth ratio calculations Date: Sat, 2 May 2026 20:40:07 -0400 Message-ID: <20260503004007.933354-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <2026050101-glamorous-absurd-e506@gregkh> References: <2026050101-glamorous-absurd-e506@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Joseph Salisbury [ Upstream commit c6e80201e057dfb7253385e60bf541121bf5dc33 ] to_ratio() computes BW_SHIFT-scaled bandwidth ratios from u64 period and runtime values, but it returns unsigned long. tg_rt_schedulable() also stores the current group limit and the accumulated child sum in unsigned long. On 32-bit builds, large bandwidth ratios can be truncated and the RT group sum can wrap when enough siblings are present. That can let an overcommitted RT hierarchy pass the schedulability check, and it also narrows the helper result for other callers. Return u64 from to_ratio() and use u64 for the RT group totals so bandwidth ratios are preserved and compared at full width on both 32-bit and 64-bit builds. Fixes: b40b2e8eb521 ("sched: rt: multi level group constraints") Assisted-by: Codex:GPT-5 Signed-off-by: Joseph Salisbury Signed-off-by: Peter Zijlstra (Intel) Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260403210014.2713404-1-joseph.salisbury@oracle.com [ dropped `extern` keyword from `to_ratio()` declaration ] Signed-off-by: Sasha Levin --- kernel/sched/core.c | 2 +- kernel/sched/rt.c | 2 +- kernel/sched/sched.h | 2 +- 3 files changed, 3 insertions(+), 3 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index e5173a48eb9b0..bcb313b1e1fd3 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3328,7 +3328,7 @@ void sched_post_fork(struct task_struct *p, struct kernel_clone_args *kargs) uclamp_post_fork(p); } -unsigned long to_ratio(u64 period, u64 runtime) +u64 to_ratio(u64 period, u64 runtime) { if (runtime == RUNTIME_INF) return BW_UNIT; diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index cc6950fc6061e..2c49da90566b5 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -2527,7 +2527,7 @@ static int tg_rt_schedulable(struct task_group *tg, void *data) { struct rt_schedulable_data *d = data; struct task_group *child; - unsigned long total, sum = 0; + u64 total, sum = 0; u64 period, runtime; period = ktime_to_ns(tg->rt_bandwidth.rt_period); diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 5f17507bd66b8..2a43d95dad386 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1956,7 +1956,7 @@ extern void init_dl_inactive_task_timer(struct sched_dl_entity *dl_se); #define RATIO_SHIFT 8 #define MAX_BW_BITS (64 - BW_SHIFT) #define MAX_BW ((1ULL << MAX_BW_BITS) - 1) -unsigned long to_ratio(u64 period, u64 runtime); +u64 to_ratio(u64 period, u64 runtime); extern void init_entity_runnable_average(struct sched_entity *se); extern void post_init_entity_util_avg(struct task_struct *p); -- 2.53.0