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 C2BDB26B942 for ; Mon, 20 Oct 2025 15:37:05 +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=1760974627; cv=none; b=cyw/THg0uKYbKTSqjsnE/h7w12n20Pc5XZYIudd176Q9JgaLqxkd6lyuEklPpqbPiVHK5FLgIqHh7mmvz2sfpNqAUP563T7x55GmU0sg7Gef5vErbjHKqpKx+mLWACeSvDxQ6H2+uIpdKKIMQGq/L9DpKMxN27MDwrWHI/Ttnuk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760974627; c=relaxed/simple; bh=WRIoYWnrI3ksQRrwE0fbaPIniiZCAjSCVqFuxUI4o/s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=GmpDd6EGIizTTPQKHYqBPPnjTGWm6F69jcy585hV704ociLth050FJtc4hi94hNJU2FjKANFrFtFiwPuddYjqfkZ2vG7HICSbI5P1HZEUUA+r29F4jKztoEV+hX7+zgsM8LXQt5zf1qSqzwBMVWTR8UAXjOsi/DxTxe3RCs7PqE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=DB1F13MU; 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="DB1F13MU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A75D8C4CEF9; Mon, 20 Oct 2025 15:37:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1760974625; bh=WRIoYWnrI3ksQRrwE0fbaPIniiZCAjSCVqFuxUI4o/s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=DB1F13MUcODtmYbtENOJSW3wyEIdzO5mIP24W0mU87778FrxkA41ZcrZ8uzcYzuXr k6dWbTGts4gzRJIoWYY80aTLVeaMexE2dIH+fJFuqda1/2qUpIwSi/PqBcYel7HV4L Mg8t9t7VGbCAoXiZxfFrioloytRqg7yrGTTGqK/c5aJsolyG9r9f/nZcAqU1GTGr5K tmiph/fIJI0vwCM+lq+2J7bCckn6RPjY1KbA4sCPFQVOg9Ol7mO4+jPb4LPz4oILHU fSKDIcwtn+w9uUIedv4NUiyTuuKXuXkWy1RBIu/9y0F2/7kC+sM0XyLvj28toRXiMm K9Tsf6Ocz07yw== From: Sasha Levin To: stable@vger.kernel.org Cc: Xiao Liang , Herbert Xu , Sasha Levin Subject: [PATCH 6.12.y] padata: Reset next CPU when reorder sequence wraps around Date: Mon, 20 Oct 2025 11:37:02 -0400 Message-ID: <20251020153702.1820394-1-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <2025101649-sector-ruined-1f7a@gregkh> References: <2025101649-sector-ruined-1f7a@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: Xiao Liang [ Upstream commit 501302d5cee0d8e8ec2c4a5919c37e0df9abc99b ] When seq_nr wraps around, the next reorder job with seq 0 is hashed to the first CPU in padata_do_serial(). Correspondingly, need reset pd->cpu to the first one when pd->processed wraps around. Otherwise, if the number of used CPUs is not a power of 2, padata_find_next() will be checking a wrong list, hence deadlock. Fixes: 6fc4dbcf0276 ("padata: Replace delayed timer with immediate workqueue in padata_reorder") Cc: Signed-off-by: Xiao Liang Signed-off-by: Herbert Xu [ relocated fix to padata_find_next() using pd->processed and pd->cpu structure fields ] Signed-off-by: Sasha Levin --- kernel/padata.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/padata.c b/kernel/padata.c index 3e0ef0753e73e..c3810f5bd7156 100644 --- a/kernel/padata.c +++ b/kernel/padata.c @@ -290,7 +290,11 @@ static struct padata_priv *padata_find_next(struct parallel_data *pd, if (remove_object) { list_del_init(&padata->list); ++pd->processed; - pd->cpu = cpumask_next_wrap(cpu, pd->cpumask.pcpu, -1, false); + /* When sequence wraps around, reset to the first CPU. */ + if (unlikely(pd->processed == 0)) + pd->cpu = cpumask_first(pd->cpumask.pcpu); + else + pd->cpu = cpumask_next_wrap(cpu, pd->cpumask.pcpu, -1, false); } spin_unlock(&reorder->lock); -- 2.51.0