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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 65817C433EF for ; Fri, 19 Nov 2021 07:01:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 44D2661AA7 for ; Fri, 19 Nov 2021 07:01:15 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233120AbhKSHEP (ORCPT ); Fri, 19 Nov 2021 02:04:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42242 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232201AbhKSHEO (ORCPT ); Fri, 19 Nov 2021 02:04:14 -0500 Received: from mail-pg1-x531.google.com (mail-pg1-x531.google.com [IPv6:2607:f8b0:4864:20::531]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 60E33C061574 for ; Thu, 18 Nov 2021 23:01:13 -0800 (PST) Received: by mail-pg1-x531.google.com with SMTP id b4so7831522pgh.10 for ; Thu, 18 Nov 2021 23:01:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=8p47yJxzaBJgNNK9+SElB+OrwH4KzAUJIu2lK10OypQ=; b=ZFJp0TCSWOWZQLnddVGFqUo/BIk9uNJMrRJsftAkkoK6ow4kFS83Ak2vm8Q1OznVbq XQIbiA3I6euCEcpoR7tb4RKEIUPEMM1rMwWZts/jH3P/q1ubzOllq8nmO8FM0VUpCHal oN8nNd0nKS7F0H2DFNXnR7QI4HWQbr3o2B7ewEd7nhIov0pV47qqmX2VGfWCi+b631cr ZAINWCszY2VwH9e3BOe8P6iSESPETqfLrY0uKQRx9WdFlOMZAFE/97UmOzhXGWCA+7xd zqVHgyQnSPG/jujDfjIqNV48d2oUelaq8h1fmD6qtAKbdmkNUveex44E0JtSYmIXQrsJ 2iBA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=8p47yJxzaBJgNNK9+SElB+OrwH4KzAUJIu2lK10OypQ=; b=UfpREYh9h+G2bZMjrkYBKFiBn581ppml45PXiP//RTx9PT8l2BlXzmOqwDg2dzSzas gdPUo7BBMj1CzHskqp+M1WdxIJhJ1g2oSCzkcOFXiBPbwn2pUnxFG6TGAWwnFeYY5+nJ QCJWRjYJ8/GDA9TzGhjQYsSrss1+yF4rHUcQusK7EUhenkvnsdwodpPgJnx6Ir2K3F5s I9FO4iD/kn9LGnU4C7qAIsqA7zwKc3rPbRdVLX1y5VUsxkX9lF7Sj5kGt4Yyf+ryb+ne +f5Fh+sz7jofzOMOSyckwgfHcYQgfihkwsj8c39uzwChIA8z0nRy1TCnx0g7Cf0lEa5G 5vYA== X-Gm-Message-State: AOAM5324YJrOaBm+5MnfLp8BmXIT7lu/5vKOIdHADIkAcQi08O4pPL2K aO+WCCSGoEahAnX76Ap+0l7L8Q== X-Google-Smtp-Source: ABdhPJzkUTCrq95HBFbLoKRFLMhkI67/vAcmTT2UP14n374SY0AA9/tSZSr0LfdDYqLGUIgEoenSwg== X-Received: by 2002:a62:b606:0:b0:47b:e32f:9ca with SMTP id j6-20020a62b606000000b0047be32f09camr61248842pff.57.1637305272927; Thu, 18 Nov 2021 23:01:12 -0800 (PST) Received: from localhost.localdomain ([139.177.225.245]) by smtp.gmail.com with ESMTPSA id r2sm1255382pgm.4.2021.11.18.23.01.08 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Thu, 18 Nov 2021 23:01:12 -0800 (PST) From: Muchun Song To: dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, hpa@zytor.com Cc: x86@kernel.org, linux-kernel@vger.kernel.org, duanxiongchun@bytedance.com, zhengqi.arch@bytedance.com, Muchun Song Subject: [RFC PATCH] x86/fault: move might_sleep() out of mmap read lock Date: Fri, 19 Nov 2021 14:58:31 +0800 Message-Id: <20211119065831.31406-1-songmuchun@bytedance.com> X-Mailer: git-send-email 2.21.0 (Apple Git-122) MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The mmap lock is supposed to be a contended lock sometimes, scheduling to other task with holding mmap read lock does not seems to be a wise choice. So move it to the front of mmap_read_trylock(). Although mmap_read_lock() implies a might_sleep(), I think redundant check is not a problem since this task is about to sleep and it is not a hot path. Signed-off-by: Muchun Song --- arch/x86/mm/fault.c | 9 ++------- 1 file changed, 2 insertions(+), 7 deletions(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 4bfed53e210e..22fd1dfafa3d 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -1323,6 +1323,8 @@ void do_user_addr_fault(struct pt_regs *regs, } #endif + might_sleep(); + /* * Kernel-mode access to the user address space should only occur * on well-defined single instructions listed in the exception @@ -1346,13 +1348,6 @@ void do_user_addr_fault(struct pt_regs *regs, } retry: mmap_read_lock(mm); - } else { - /* - * The above down_read_trylock() might have succeeded in - * which case we'll have missed the might_sleep() from - * down_read(): - */ - might_sleep(); } vma = find_vma(mm, address); -- 2.11.0