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 A11BD26E6F9 for ; Mon, 20 Oct 2025 15:40:53 +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=1760974853; cv=none; b=lgG0DeBREBSGCvOSfm0+mKi8GE9ZR3mDyOIC6QjO32g+rpYipbFTFxPSq5NDfCCfqiK13H1Y10NLtRYfqtKZpGvcvP0jNgRSwGHSLpM9hdOGGroUCt0t0BKWNG21VCEzx0UMAhTNt3TZJXlulkevYb9mhI3ryVbq3phznGAFxcY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760974853; c=relaxed/simple; bh=5UH8O1zKExuiXYO+DlKN9FVNlITqkAP61WxqgOWya8c=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Ooo/sHylHBkMWUL0cgnVdrTRLstBLGwFrHDqQsNWaXSzTBbwQaz0bY9s/b4Gsyj6+2VV39NyINzLXaZ2yHpccbQmQcot/5KPDWf+2EQ09Lt8CBEhoqIcJH6MYsD4BFNVEs4WYANqHNpfKzIIQFob3yNnO8lHUkXndXft5N/e4zw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ml3ipnNv; 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="Ml3ipnNv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id AB45FC4CEFE; Mon, 20 Oct 2025 15:40:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1760974853; bh=5UH8O1zKExuiXYO+DlKN9FVNlITqkAP61WxqgOWya8c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ml3ipnNv3sJISFm8TfqSJfj8OAZ4sghmxkuD4Xn3+py1Ibj+4BqDricMYK3XMouyI 1N3cYZS06kpaqSkw6LvjOFRfZ0WJj3wb1MWX2jEzDZffYxEs7fSPGdyNesU3Uzd/fk VptQrhMfiC1ixegulVUkb/J89j8vg+/YxxIRlbHXM0khAnyUKx8mG1oJFliq65CeHY i6RvqzReRt93T6tdVr9obiDatmZ34TeH5SDGJCG/YnMpw12VPkes7LB/mbg6u9GJPC i7Bh5tIyfb8+wv2UvfA90U8wKqXfpzVcTV6dWKajFSPKXS0p4jqf6Y+yKH7Zss5y01 rdiBbf0YkEyIA== From: Sasha Levin To: stable@vger.kernel.org Cc: Xiao Liang , Herbert Xu , Sasha Levin Subject: [PATCH 5.10.y] padata: Reset next CPU when reorder sequence wraps around Date: Mon, 20 Oct 2025 11:40:50 -0400 Message-ID: <20251020154050.1821767-1-sashal@kernel.org> X-Mailer: git-send-email 2.51.0 In-Reply-To: <2025101651-sizing-subfloor-8c1d@gregkh> References: <2025101651-sizing-subfloor-8c1d@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 [ moved from padata_reorder() local variables to padata_find_next() using pd->processed and pd->cpu struct members ] 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 1bd61add09158..6c8a141b5c4b2 100644 --- a/kernel/padata.c +++ b/kernel/padata.c @@ -295,7 +295,11 @@ 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