From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-1825685-1518708617-2-13028731280381177921 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.001, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='US', FromHeader='org', MailFrom='org' X-Spam-charsets: plain='UTF-8' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1518708616; b=qZYLZgd3brh6xKNRCtlQKvu+4wypiOymyISjrOixF13m8TT HJUqpPb6Vv97nWQ3PP8xCxFJxrDMQqIGjR1TSMXJ36XMpbCwLE+sDmh640ngjtJF xilN/3OtnSgWksmcHwQVxk950/UYziChUltn9rEqu5WtTaaraJwsH7BepVg2fbJe K5hlMFZ1sZTbSD3GLGVVswJymwgVracnFs0PxrcKecc6mM0sqnWsSA9yJh8NhYyR 9EaYg7Fgdo3tDUN3gJSsabhnNjc1OY5txrX9J7VIvOAtsOoHuPK5rYzwy8bI2fyO YzTLqfAFecnTlB8O9pk3QB28J7jVyadTk6QUOtQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-type:sender :list-id; s=arctest; t=1518708616; bh=wFJWLcbmfPTfVsYuDcFvDmbx69 VaJEx1J0U0Ax95blQ=; b=OvDsEicitQtKoot5YfgmBjBblQdeiASLjIx/3wta0x ao4FFlvxGk6ht7fC8CBoD73C4nLbHFGyRO4xW2KJRkPmwLc6H+MYM4u1MI68IZWH xWVgT8K4J59AGrRVOFAJF6AvLzfmhNpRWSA1vZ8SHtGfo0k0kEaHms/ia3mkkYW0 5y+GlYeN9c9KwawqhrmqRVG8RR/XkRNex6kBYWOL324xlbKjxfOSc3HklPL2ecZc OFsX/2m64zbaOEu4uJDN8Qoxswq9xzUmfgFpaJ5XeqFHN1bKuCooKk6IkwaMyJlC jNvfCAUhqicoajHi76I0pmFyShdbtYVL3IseKJ2jpOlA== ARC-Authentication-Results: i=1; mx6.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes Authentication-Results: mx6.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1164170AbeBOPaN (ORCPT ); Thu, 15 Feb 2018 10:30:13 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:54946 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1163719AbeBOPaK (ORCPT ); Thu, 15 Feb 2018 10:30:10 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Omar Sandoval , Jens Axboe , Peter Zijlstra , Linus Torvalds , Thomas Gleixner , kernel-team@fb.com, Ingo Molnar Subject: [PATCH 4.14 008/195] sched/wait: Fix add_wait_queue() behavioral change Date: Thu, 15 Feb 2018 16:14:59 +0100 Message-Id: <20180215151706.164372057@linuxfoundation.org> X-Mailer: git-send-email 2.16.1 In-Reply-To: <20180215151705.738773577@linuxfoundation.org> References: <20180215151705.738773577@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Omar Sandoval commit c6b9d9a33029014446bd9ed84c1688f6d3d4eab9 upstream. The following cleanup commit: 50816c48997a ("sched/wait: Standardize internal naming of wait-queue entries") ... unintentionally changed the behavior of add_wait_queue() from inserting the wait entry at the head of the wait queue to the tail of the wait queue. Beyond a negative performance impact this change in behavior theoretically also breaks wait queues which mix exclusive and non-exclusive waiters, as non-exclusive waiters will not be woken up if they are queued behind enough exclusive waiters. Signed-off-by: Omar Sandoval Reviewed-by: Jens Axboe Acked-by: Peter Zijlstra Cc: Linus Torvalds Cc: Thomas Gleixner Cc: kernel-team@fb.com Fixes: ("sched/wait: Standardize internal naming of wait-queue entries") Link: http://lkml.kernel.org/r/a16c8ccffd39bd08fdaa45a5192294c784b803a7.1512544324.git.osandov@fb.com Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- kernel/sched/wait.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/kernel/sched/wait.c +++ b/kernel/sched/wait.c @@ -27,7 +27,7 @@ void add_wait_queue(struct wait_queue_he wq_entry->flags &= ~WQ_FLAG_EXCLUSIVE; spin_lock_irqsave(&wq_head->lock, flags); - __add_wait_queue_entry_tail(wq_head, wq_entry); + __add_wait_queue(wq_head, wq_entry); spin_unlock_irqrestore(&wq_head->lock, flags); } EXPORT_SYMBOL(add_wait_queue);