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 DE2D7C433FE for ; Tue, 15 Mar 2022 22:58:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1352432AbiCOW7r (ORCPT ); Tue, 15 Mar 2022 18:59:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46956 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237649AbiCOW7o (ORCPT ); Tue, 15 Mar 2022 18:59:44 -0400 Received: from mail-pj1-x1035.google.com (mail-pj1-x1035.google.com [IPv6:2607:f8b0:4864:20::1035]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1551C4BFFF; Tue, 15 Mar 2022 15:58:32 -0700 (PDT) Received: by mail-pj1-x1035.google.com with SMTP id mj15-20020a17090b368f00b001c637aa358eso3200801pjb.0; Tue, 15 Mar 2022 15:58:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=tpBIy3wDvQGfwH9ls4xR2jLiqxVzU1kgqh+8V0SkolM=; b=qhVli5fhBKxbJaOS2y1VJDUNLLAHqtWf2jL00Tb9InM7nKWn4akLb4Dppd9KqCQKqi 29cdJh6WElt9yN+hN0MGEAy86fyKb97KzWJeXa5y5Py0+U53ADdqfSOIUXPz/3KD0aCx LYg309WkcuTmxoUEewGSXr5AmEYfaMpG17srZRwbk1T6+BZTFGLsmTPDE4D11BJMD5lF 7qtxuk/B1mwpl/dYL30r5UXrw4xtVlhwUSI9lz/0KcxWl9SWxD02iBLzrQqIOYNa3U0a 8tzs9T/kBvbHrxh92yWpOTQmjEta9rsFny/9HualjYsEDQlNDdMilYFxEO84SAEQjnO9 OffQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=tpBIy3wDvQGfwH9ls4xR2jLiqxVzU1kgqh+8V0SkolM=; b=iU611Tun+AOcpaD5GdclD5ZLwIN0f5/F6MBOWHY1RuWvEj9C2tXNBZNQ+CpmqyZmHN sjve7JwPVQGbhstK64zp6TVe9Y8uMYtsvyg45RVmBuKENKWyThY+l7owRW7EZUqn7j2C VFDm/MbxJcabwTLd/y76a4Xxfkf6y8Wkanti4v3ohbqzCGTMhup/Rx+4ZupAPuchM6Zd TizuigVxg8/AD2/yGUW1qBYh/32/GZdtE5u5h/0x7XEp3dW9yAEPJVRXuaco5YHDj40n jo3eRCQ5dGr8NgAeSQJEq3YDygumrx26WUWBtoYYiisdeDV++LBsGYrGwBBZlfL6GhGJ jyIQ== X-Gm-Message-State: AOAM532BSuLxttdDiVJX3/1DpCtMrI80mKsnuMOlbQ4jZmf7J9bwMdg1 qQhjiJo6HDIf2Q9bnqTxbkA= X-Google-Smtp-Source: ABdhPJzvr4L3c32sdszzPbBKgCVWu3n+sX8w08P6WyBLH8X2gU41vVQJ2efLIV0AJFg2T4fNGpVv0A== X-Received: by 2002:a17:90b:4c41:b0:1be:f5d3:78eb with SMTP id np1-20020a17090b4c4100b001bef5d378ebmr7001311pjb.187.1647385111454; Tue, 15 Mar 2022 15:58:31 -0700 (PDT) Received: from google.com ([2620:15c:211:201:7484:dc22:fe49:91cb]) by smtp.gmail.com with ESMTPSA id k3-20020a056a00168300b004f7e60da26csm139387pfc.182.2022.03.15.15.58.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 15 Mar 2022 15:58:30 -0700 (PDT) Sender: Minchan Kim Date: Tue, 15 Mar 2022 15:58:28 -0700 From: Minchan Kim To: Charan Teja Kalla Cc: akpm@linux-foundation.org, surenb@google.com, vbabka@suse.cz, rientjes@google.com, sfr@canb.auug.org.au, edgararriaga@google.com, nadav.amit@gmail.com, mhocko@suse.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, "# 5 . 10+" Subject: Re: [PATCH V2,2/2] mm: madvise: skip unmapped vma holes passed to process_madvise Message-ID: References: <4f091776142f2ebf7b94018146de72318474e686.1647008754.git.quic_charante@quicinc.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4f091776142f2ebf7b94018146de72318474e686.1647008754.git.quic_charante@quicinc.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Mar 11, 2022 at 08:59:06PM +0530, Charan Teja Kalla wrote: > The process_madvise() system call is expected to skip holes in vma > passed through 'struct iovec' vector list. But do_madvise, which > process_madvise() calls for each vma, returns ENOMEM in case of unmapped > holes, despite the VMA is processed. > Thus process_madvise() should treat ENOMEM as expected and consider the > VMA passed to as processed and continue processing other vma's in the > vector list. Returning -ENOMEM to user, despite the VMA is processed, > will be unable to figure out where to start the next madvise. > Fixes: ecb8ac8b1f14("mm/madvise: introduce process_madvise() syscall: an external memory hinting API") > Cc: # 5.10+ Hmm, not sure whether it's stable material since it changes semantic of API. It would be better to change the semantic from 5.19 with man page update to specify the change. > Signed-off-by: Charan Teja Kalla > --- > Changes in V2: > -- Fixed handling of ENOMEM by process_madvise(). > -- Patch doesn't exist in V1. > > mm/madvise.c | 9 ++++++++- > 1 file changed, 8 insertions(+), 1 deletion(-) > > diff --git a/mm/madvise.c b/mm/madvise.c > index e97e6a9..14fb76d 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -1426,9 +1426,16 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec, > > while (iov_iter_count(&iter)) { > iovec = iov_iter_iovec(&iter); > + /* > + * do_madvise returns ENOMEM if unmapped holes are present > + * in the passed VMA. process_madvise() is expected to skip > + * unmapped holes passed to it in the 'struct iovec' list > + * and not fail because of them. Thus treat -ENOMEM return > + * from do_madvise as valid and continue processing. > + */ > 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); > } > -- > 2.7.4 >