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 B769E1E9078; Tue, 15 Oct 2024 11:40:10 +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=1728992410; cv=none; b=aid99Q1MMmGl9X1AETjNElFeHTrNSpkO9TXv0/p2d8SLNtSFU7Peh4KU7gqb4x1T8LiYIWx+xZzspEtaeRoCsEuhKlrUxGZf/3Ge2LR4CjDp3XMF2QSCB92QFDiR2YeQ/hyiKEOxbfYqXvNQ2vIm4yVuNhXlJgi9EYt57Vx2x7I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728992410; c=relaxed/simple; bh=1nO4Y8eCh2rhxlJHUOqAb+guTv6L7ELKP5qGzqXoHiY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=YibHcv2W45QzfL5EdMkqPR0mxznfiftivmbfEE98Ji3RJyF18J90VYCq2Pf88pNcjCVzZuimPtEqQEmWH45Y2goOrFJ95/jM9dv1MDi6oH7oVR/O2EVIh0Z59XivPVXwASv1xUHPjx3Fc2K61ZcciDolJ7pklvRzH9qMadJFseQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=rj8RlZQy; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="rj8RlZQy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D2017C4CEC6; Tue, 15 Oct 2024 11:40:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1728992410; bh=1nO4Y8eCh2rhxlJHUOqAb+guTv6L7ELKP5qGzqXoHiY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=rj8RlZQyn0FnInlOOfQqSbuFG7T27tGr52mk1fIU1RVLL94L5Oiwxn+VsNL9wEDql blzSrqlvop+dKpZOCwIR9+NsDrTRgvTo3R1CJb6LNTGb6456OgVdXMyxof03aFs9Hq 5feqsZrf5vY2zGpQK1rEU+mih3OUnHVl/l0KSejA= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Kamlesh Gurudasani , =?UTF-8?q?=C2=A0=20Waiman=20Long?= , Daniel Jordan , Herbert Xu , Sasha Levin Subject: [PATCH 5.15 107/691] padata: Honor the callers alignment in case of chunk_size 0 Date: Tue, 15 Oct 2024 13:20:55 +0200 Message-ID: <20241015112444.606293841@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241015112440.309539031@linuxfoundation.org> References: <20241015112440.309539031@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kamlesh Gurudasani [ Upstream commit 24cc57d8faaa4060fd58adf810b858fcfb71a02f ] In the case where we are forcing the ps.chunk_size to be at least 1, we are ignoring the caller's alignment. Move the forcing of ps.chunk_size to be at least 1 before rounding it up to caller's alignment, so that caller's alignment is honored. While at it, use max() to force the ps.chunk_size to be at least 1 to improve readability. Fixes: 6d45e1c948a8 ("padata: Fix possible divide-by-0 panic in padata_mt_helper()") Signed-off-by: Kamlesh Gurudasani Acked-by:  Waiman Long Acked-by: Daniel Jordan Signed-off-by: Herbert Xu Signed-off-by: Sasha Levin --- kernel/padata.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/padata.c b/kernel/padata.c index 7c52f9de5d4ec..f567b54d79639 100644 --- a/kernel/padata.c +++ b/kernel/padata.c @@ -503,9 +503,12 @@ void __init padata_do_multithreaded(struct padata_mt_job *job) * thread function. Load balance large jobs between threads by * increasing the number of chunks, guarantee at least the minimum * chunk size from the caller, and honor the caller's alignment. + * Ensure chunk_size is at least 1 to prevent divide-by-0 + * panic in padata_mt_helper(). */ ps.chunk_size = job->size / (ps.nworks * load_balance_factor); ps.chunk_size = max(ps.chunk_size, job->min_chunk); + ps.chunk_size = max(ps.chunk_size, 1ul); ps.chunk_size = roundup(ps.chunk_size, job->align); /* -- 2.43.0