From mboxrd@z Thu Jan 1 00:00:00 1970 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 520B8C678D5 for ; Wed, 8 Mar 2023 21:59:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229606AbjCHV7I (ORCPT ); Wed, 8 Mar 2023 16:59:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36374 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229690AbjCHV7H (ORCPT ); Wed, 8 Mar 2023 16:59:07 -0500 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 01A6E64278 for ; Wed, 8 Mar 2023 13:59:05 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 84B436198C for ; Wed, 8 Mar 2023 21:59:05 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D6433C433D2; Wed, 8 Mar 2023 21:59:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1678312745; bh=PE+om2vZrNvjcDg2VNHcQh7ZTxfeme92VXf2+jmM098=; h=Date:To:From:Subject:From; b=roKF6JxXmDQnsgVourt3Uy07eHVonB9jyLhB5nLwwL4VJdqVrfSmzB5yLaCE1XnLG WrVyYuZnP0KYNN7xVa2tWt52yoJGvFb6ij9cgdg8Is5oU1fB47xC/bApTGs65ekSIy 354UippxtJ2OX0Z6iIphPhxvZS9hQtyb4TGSkewE= Date: Wed, 08 Mar 2023 13:59:04 -0800 To: mm-commits@vger.kernel.org, xmu@redhiat.com, viro@zeniv.linux.org.uk, soheil@google.com, jacob.e.keller@intel.com, ebiggers@kernel.org, cmaiolino@redhat.com, brauner@kernel.org, axboe@kernel.dk, pabeni@redhat.com, akpm@linux-foundation.org From: Andrew Morton Subject: + epoll-use-refcount-to-reduce-ep_mutex-contention-v5.patch added to mm-nonmm-unstable branch Message-Id: <20230308215904.D6433C433D2@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: epoll-use-refcount-to-reduce-ep_mutex-contention-v5 has been added to the -mm mm-nonmm-unstable branch. Its filename is epoll-use-refcount-to-reduce-ep_mutex-contention-v5.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/epoll-use-refcount-to-reduce-ep_mutex-contention-v5.patch This patch will later appear in the mm-nonmm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Paolo Abeni Subject: epoll-use-refcount-to-reduce-ep_mutex-contention-v5 Date: Wed, 8 Mar 2023 22:51:31 +0100 update some comments Link: https://lkml.kernel.org/r/323de732635cc3513c1837c6cbb98f012174f994.1678312201.git.pabeni@redhat.com Tested-by: Xiumei Mu Reviewed-by: Jacob Keller Acked-by: Soheil Hassas Yeganeh Signed-off-by: Paolo Abeni Cc: Al Viro Cc: Carlos Maiolino Cc: Christian Brauner Cc: Eric Biggers Cc: Jens Axboe Signed-off-by: Andrew Morton --- --- a/fs/eventpoll.c~epoll-use-refcount-to-reduce-ep_mutex-contention-v5 +++ a/fs/eventpoll.c @@ -714,6 +714,8 @@ static void ep_free(struct eventpoll *ep * Removes a "struct epitem" from the eventpoll RB tree and deallocates * all the associated resources. Must be called with "mtx" held. * If the dying flag is set, do the removal only if force is true. + * This prevents ep_clear_and_put() from dropping all the ep references + * while running concurrently with eventpoll_release_file(). * Returns true if the eventpoll can be disposed. */ static bool __ep_remove(struct eventpoll *ep, struct epitem *epi, bool force) @@ -941,14 +943,13 @@ void eventpoll_release_file(struct file bool dispose; /* - * Use the 'dying' flag to prevent a concurrent ep_cleat_and_put() from + * Use the 'dying' flag to prevent a concurrent ep_clear_and_put() from * touching the epitems list before eventpoll_release_file() can access * the ep->mtx. */ again: spin_lock(&file->f_lock); if (file->f_ep && file->f_ep->first) { - /* detach from ep tree */ epi = hlist_entry(file->f_ep->first, struct epitem, fllink); epi->dying = true; spin_unlock(&file->f_lock); _ Patches currently in -mm which might be from pabeni@redhat.com are epoll-use-refcount-to-reduce-ep_mutex-contention.patch epoll-use-refcount-to-reduce-ep_mutex-contention-v5.patch