From patchwork Fri Jan 27 18:46:49 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Rik van Riel X-Patchwork-Id: 13119189 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6AACAC54EAA for ; Fri, 27 Jan 2023 18:47:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235176AbjA0SrQ (ORCPT ); Fri, 27 Jan 2023 13:47:16 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50986 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235088AbjA0SrO (ORCPT ); Fri, 27 Jan 2023 13:47:14 -0500 Received: from shelob.surriel.com (shelob.surriel.com [96.67.55.147]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 41BBD757BE; Fri, 27 Jan 2023 10:47:07 -0800 (PST) Received: from imladris.home.surriel.com ([10.0.13.28] helo=imladris.surriel.com) by shelob.surriel.com with esmtpsa (TLS1.2) tls TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from ) id 1pLTkW-0008Mm-0x; Fri, 27 Jan 2023 13:46:56 -0500 From: Rik van Riel To: viro@zeniv.linux.org.uk, linux-kernel@vger.kernel.org, kernel-team@meta.com, linux-fsdevel@vger.kernel.org, gscrivan@redhat.com Subject: [PATCH v3 0/2] ipc,namespace: fix free vs allocation race Date: Fri, 27 Jan 2023 13:46:49 -0500 Message-Id: <20230127184651.3681682-1-riel@surriel.com> X-Mailer: git-send-email 2.38.1 MIME-Version: 1.0 Sender: riel@shelob.surriel.com Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org The IPC namespace code frees ipc_namespace structures asynchronously, via a work queue item. This results in ipc_namespace structures being freed very slowly, and the allocation path getting false failures since the to-be-freed ipc_namespace structures have not been freed yet. Fix that by having the allocator wait when there are ipc_namespace structures pending to be freed. Also speed up the freeing of ipc_namespace structures. We had some discussions about this last year, and ended up trying out various "nicer" ideas that did not work, so I went back to the original, with Al Viro's suggestion for a helper function: https://lore.kernel.org/all/Yg8StKzTWh+7FLuA@zeniv-ca.linux.org.uk/ This series fixes both the false allocation failures, and the slow freeing of ipc_namespace structures. v3: remove mq_put_mnt (thank you Giuseppe) v2: a few more fs/namespace.c cleanups suggested by Al Viro (thank you!) Tested-by: Giuseppe Scrivano