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 X-Spam-Level: X-Spam-Status: No, score=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2130DC433E0 for ; Tue, 2 Jun 2020 04:48:44 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D92AE2074B for ; Tue, 2 Jun 2020 04:48:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="vk+Bxe70" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D92AE2074B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 0332A280021; Tue, 2 Jun 2020 00:48:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 013B7280012; Tue, 2 Jun 2020 00:48:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E64E7280021; Tue, 2 Jun 2020 00:48:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0062.hostedemail.com [216.40.44.62]) by kanga.kvack.org (Postfix) with ESMTP id C47F9280012 for ; Tue, 2 Jun 2020 00:48:35 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 8A861180AD804 for ; Tue, 2 Jun 2020 04:48:35 +0000 (UTC) X-FDA: 76883040990.14.roof21_2dddc9cf02a09 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin14.hostedemail.com (Postfix) with ESMTP id 6F02B1822987A for ; Tue, 2 Jun 2020 04:48:35 +0000 (UTC) X-HE-Tag: roof21_2dddc9cf02a09 X-Filterd-Recvd-Size: 2353 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf47.hostedemail.com (Postfix) with ESMTP for ; Tue, 2 Jun 2020 04:48:35 +0000 (UTC) Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 460AA206C3; Tue, 2 Jun 2020 04:48:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591073314; bh=BEbYVk/2xURlo0zmpH1FxsKX4zQIAfJZsVD1cVmMwOI=; h=Date:From:To:Subject:In-Reply-To:From; b=vk+Bxe70xwE/J9e2lvFyRmOTvncInDrAvF3PL87Hugy57a7fK6lK1iW7h0Hb/Saqy sVT7WmtK1dlyApXL6ct3xmSEOArdEmMkDH1JulzCp7B++y0aBM3narZ1exDcYn3fAz C96ye/M+lCMxz987YnoHA2G3tluaYYTqeogDm8WE= Date: Mon, 01 Jun 2020 21:48:33 -0700 From: Andrew Morton To: akpm@linux-foundation.org, linux-mm@kvack.org, miles.chen@mediatek.com, mm-commits@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 057/128] mm/gup.c: further document vma_permits_fault() Message-ID: <20200602044833.p9kfndHEN%akpm@linux-foundation.org> In-Reply-To: <20200601214457.919c35648e96a2b46b573fe1@linux-foundation.org> User-Agent: s-nail v14.8.16 X-Rspamd-Queue-Id: 6F02B1822987A X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Miles Chen Subject: mm/gup.c: further document vma_permits_fault() Describe the caller's responsibilities when passing FAULT_FLAG_ALLOW_RETRY. Link: http://lkml.kernel.org/r/1586915606.5647.5.camel@mtkswgap22 Signed-off-by: Andrew Morton --- mm/gup.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/mm/gup.c~mm-gupc-further-document-vma_permits_fault +++ a/mm/gup.c @@ -1176,7 +1176,8 @@ static bool vma_permits_fault(struct vm_ * @address: user address * @fault_flags:flags to pass down to handle_mm_fault() * @unlocked: did we unlock the mmap_sem while retrying, maybe NULL if caller - * does not allow retry + * does not allow retry. If NULL, the caller must guarantee + * that fault_flags does not contain FAULT_FLAG_ALLOW_RETRY. * * This is meant to be called in the specific scenario where for locking reasons * we try to access user memory in atomic context (within a pagefault_disable() _