From patchwork Wed Mar 9 05:27:59 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Charan Teja Kalla X-Patchwork-Id: 12774759 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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 96CAEC433EF for ; Wed, 9 Mar 2022 05:28:47 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id F13F78D000D; Wed, 9 Mar 2022 00:28:46 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EC3538D0001; Wed, 9 Mar 2022 00:28:46 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D8BD28D000D; Wed, 9 Mar 2022 00:28:46 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.hostedemail.com [64.99.140.27]) by kanga.kvack.org (Postfix) with ESMTP id C6D408D0001 for ; Wed, 9 Mar 2022 00:28:46 -0500 (EST) Received: from smtpin12.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 8DE59207AE for ; Wed, 9 Mar 2022 05:28:46 +0000 (UTC) X-FDA: 79223718252.12.DEF24EE Received: from alexa-out.qualcomm.com (alexa-out.qualcomm.com [129.46.98.28]) by imf26.hostedemail.com (Postfix) with ESMTP id 8F3FA140003 for ; Wed, 9 Mar 2022 05:28:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1646803726; x=1678339726; h=from:to:cc:subject:date:message-id:mime-version; bh=97CBgfKzG/hf6ld2R9U1iapWBregjuYMrjFowuf2y98=; b=EI+nFLA2KexAqCrNWFnqBlcmS4JUcIQSF86nPaJHvnmaazumCHITDlmf 01Verc5fOYSqNsoemX0JQJ1ygs5rWHAmbhAIXf+sUyDk/azD58KIFNSpk F9H2hz/uLn9f3CyvLPerfAwZegCbI62PY4/j+V/Ym+1y93IwI+phKC/ls Y=; Received: from ironmsg08-lv.qualcomm.com ([10.47.202.152]) by alexa-out.qualcomm.com with ESMTP; 08 Mar 2022 21:28:43 -0800 X-QCInternal: smtphost Received: from nasanex01c.na.qualcomm.com ([10.47.97.222]) by ironmsg08-lv.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 08 Mar 2022 21:28:44 -0800 Received: from nalasex01a.na.qualcomm.com (10.47.209.196) by nasanex01c.na.qualcomm.com (10.47.97.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.15; Tue, 8 Mar 2022 21:28:42 -0800 Received: from hu-charante-hyd.qualcomm.com (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.15; Tue, 8 Mar 2022 21:28:38 -0800 From: Charan Teja Kalla To: , , , , , , CC: , , Charan Teja Kalla Subject: [PATCH] mm: madvise: return correct bytes advised with process_madvise Date: Wed, 9 Mar 2022 10:57:59 +0530 Message-ID: <1646803679-11433-1-git-send-email-quic_charante@quicinc.com> X-Mailer: git-send-email 2.7.4 MIME-Version: 1.0 X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nalasex01a.na.qualcomm.com (10.47.209.196) X-Rspamd-Server: rspam10 X-Rspam-User: X-Stat-Signature: 1wu5r7riocqib3y77x5oo7icuzn8ujmy Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=quicinc.com header.s=qcdkim header.b=EI+nFLA2; spf=pass (imf26.hostedemail.com: domain of quic_charante@quicinc.com designates 129.46.98.28 as permitted sender) smtp.mailfrom=quic_charante@quicinc.com; dmarc=pass (policy=none) header.from=quicinc.com X-Rspamd-Queue-Id: 8F3FA140003 X-HE-Tag: 1646803725-75020 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000025, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: The process_madvise() system call returns error even after processing some VMA's passed in the 'struct iovec' vector list which leaves the user confused to know where to restart the advise next. It is also against this syscall man page[1] documentation where it mentions that "return value may be less than the total number of requested bytes, if an error occurred after some iovec elements were already processed.". Consider a user passed 10 VMA's in the 'struct iovec' vector list of which 9 are processed but one. Then it just returns the error caused on that failed VMA despite the first 9 VMA's processed, leaving the user confused about on which VMA it is failed. Returning the number of bytes processed here can help the user to know which VMA it is failed on and thus can retry/skip the advise on that VMA. [1]https://man7.org/linux/man-pages/man2/process_madvise.2.html. Fixes: ecb8ac8b1f14("mm/madvise: introduce process_madvise() syscall: an external memory hinting API" Signed-off-by: Charan Teja Kalla --- mm/madvise.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/mm/madvise.c b/mm/madvise.c index 38d0f51..d3b49b3 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -1426,15 +1426,21 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec, while (iov_iter_count(&iter)) { iovec = iov_iter_iovec(&iter); + /* + * Even when [start, end) passed to do_madvise covers + * some unmapped addresses, it continues processing with + * returning ENOMEM at the end. Thus consider the range + * as processed when do_madvise() returns ENOMEM. + * This makes process_madvise() never returns ENOMEM. + */ ret = do_madvise(mm, (unsigned long)iovec.iov_base, iovec.iov_len, behavior); - if (ret < 0) + if (ret < 0 && ret != -ENOMEM) break; iov_iter_advance(&iter, iovec.iov_len); } - if (ret == 0) - ret = total_len - iov_iter_count(&iter); + ret = (total_len - iov_iter_count(&iter)) ? : ret; release_mm: mmput(mm);