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 878954182DB; Sat, 28 Feb 2026 17:45:28 +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=1772300728; cv=none; b=mffpy8hiSBLc+bKwRyTE0wmPNJqJ9+rdzcfKzZH8aC5BM59+yuOPFm1HsR0fkkGWj6f5muXFOLpN/pRjy1HAfUn6RA0u+yuR7eg1pcCmimJGKqVEAQ4u82v2cRT2O8oWZdujNvS6Crp94CCivVnJFIGxIilrQcnslNhBGdr+pEc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772300728; c=relaxed/simple; bh=r1CH4diocVV5/6lId/JsDHVBZyZjEV5vcT3Jy3BE2Ws=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=OsajJcTYOf/Ir+WJtBJZw6cLVwSYWmCfZhkzdPR0HEEen5PBeQ9aUVSnfHJ6Sio3hGZl3LynlAvcK/SxgKzwKTiGE3Md8XTUP0i8bMmvZmWf0oFXYz6ukkOIXGATG2V20BgCOWVtBmlNDky3616QPuAR7vci+GkEJbW6iO84148= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Nh/jtuh3; 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="Nh/jtuh3" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5598FC116D0; Sat, 28 Feb 2026 17:45:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772300728; bh=r1CH4diocVV5/6lId/JsDHVBZyZjEV5vcT3Jy3BE2Ws=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Nh/jtuh3S0Fhn15I2BkHviS0Ukirg7MkTuEYlKjjLL9Eznx39qZDGQFYewHfea227 j2mgUe8U8UIzjffXum4ew9i2FDl1nQHaCjYT+53GXGCYpV6f9ZOcpzxoje0ZRhg+fP Q1t7y3vqWgdL2RTVNzU6xq3Vo3wRt2d9TGEnDKYS/vVUqCYvO4b7FR1m2hHw0J23JJ 3VKFrf7U1kif6Ujg4g15be6Qi7dfo/D+3u8nYpxA4WuKaXQhYPIsXyxRhTwa+qITeP pNfi833n3AGh7t6vKzbKu3WZYUOb+sBTUrEoFf07qbOOVPYfR+hGnokEByDhA5mgf3 NMIOnINMDPwkg== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Shengming Hu , Petr Mladek , Ingo Molnar , Mark Brown , Thomas Gleixner , Zhang Run , Andrew Morton , Sasha Levin Subject: [PATCH 6.19 762/844] watchdog/softlockup: fix sample ring index wrap in need_counting_irqs() Date: Sat, 28 Feb 2026 12:31:15 -0500 Message-ID: <20260228173244.1509663-763-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260228173244.1509663-1-sashal@kernel.org> References: <20260228173244.1509663-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit From: Shengming Hu [ Upstream commit cafe4074a7221dca2fa954dd1ab0cf99b6318e23 ] cpustat_tail indexes cpustat_util[], which is a NUM_SAMPLE_PERIODS-sized ring buffer. need_counting_irqs() currently wraps the index using NUM_HARDIRQ_REPORT, which only happens to match NUM_SAMPLE_PERIODS. Use NUM_SAMPLE_PERIODS for the wrap to keep the ring math correct even if the NUM_HARDIRQ_REPORT or NUM_SAMPLE_PERIODS changes. Link: https://lkml.kernel.org/r/tencent_7068189CB6D6689EB353F3D17BF5A5311A07@qq.com Fixes: e9a9292e2368 ("watchdog/softlockup: Report the most frequent interrupts") Signed-off-by: Shengming Hu Reviewed-by: Petr Mladek Cc: Ingo Molnar Cc: Mark Brown Cc: Thomas Gleixner Cc: Zhang Run Cc: Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin --- kernel/watchdog.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 366122f4a0f87..70eaa77242814 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -550,7 +550,7 @@ static bool need_counting_irqs(void) u8 util; int tail = __this_cpu_read(cpustat_tail); - tail = (tail + NUM_HARDIRQ_REPORT - 1) % NUM_HARDIRQ_REPORT; + tail = (tail + NUM_SAMPLE_PERIODS - 1) % NUM_SAMPLE_PERIODS; util = __this_cpu_read(cpustat_util[tail][STATS_HARDIRQ]); return util > HARDIRQ_PERCENT_THRESH; } -- 2.51.0