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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3307BC6FD1C for ; Thu, 23 Mar 2023 15:43:52 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A05766B0075; Thu, 23 Mar 2023 11:43:51 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9B56D6B0078; Thu, 23 Mar 2023 11:43:51 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 87DB66B007B; Thu, 23 Mar 2023 11:43:51 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 787B06B0075 for ; Thu, 23 Mar 2023 11:43:51 -0400 (EDT) Received: from smtpin25.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 443351403FD for ; Thu, 23 Mar 2023 15:43:51 +0000 (UTC) X-FDA: 80600583462.25.E13F7D7 Received: from madras.collabora.co.uk (madras.collabora.co.uk [46.235.227.172]) by imf28.hostedemail.com (Postfix) with ESMTP id 4992FC0011 for ; Thu, 23 Mar 2023 15:43:49 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=collabora.com header.s=mail header.b=eNbPAtfw; spf=pass (imf28.hostedemail.com: domain of usama.anjum@collabora.com designates 46.235.227.172 as permitted sender) smtp.mailfrom=usama.anjum@collabora.com; dmarc=pass (policy=quarantine) header.from=collabora.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1679586229; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=G+HftiK3Qwj/TUj6Gmypos20PqZoXe39CSNj3hBC3gQ=; b=meBQNFuyjYFwVyjsameUrX1iSnil6556yws6WycUN3tqTK9rWX3KY2SFXyXz4WJoQzG0mH ioGBMkIVVQJOp2Ao84wIB6ydHuNricTRA1D9JnVJGJt6SUnWSkK1M2ZCAyeXxPQzY9zZo8 5CcMKCa5loi/eNCnOt6nHZbJ4pvlvwc= ARC-Authentication-Results: i=1; imf28.hostedemail.com; dkim=pass header.d=collabora.com header.s=mail header.b=eNbPAtfw; spf=pass (imf28.hostedemail.com: domain of usama.anjum@collabora.com designates 46.235.227.172 as permitted sender) smtp.mailfrom=usama.anjum@collabora.com; dmarc=pass (policy=quarantine) header.from=collabora.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1679586229; a=rsa-sha256; cv=none; b=APmb5rMJ1vhMA6MuBMiV+WRUQ/vgOBF2d2Q3PShc3wH2vBD9m8kJZWTDR0aWejnl3GZk53 VLd+fGSmCfIjp9s8cmv++0y1HEebXVyB9bBWM4dhqoW9Kyb7cMkgGeXdshjDnJSXzBj8Bk NkBc3/M4wGE13aA583R0iLT+k6oYUaw= Received: from [192.168.10.28] (unknown [39.37.168.222]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) (Authenticated sender: usama.anjum) by madras.collabora.co.uk (Postfix) with ESMTPSA id 1255366030F9; Thu, 23 Mar 2023 15:43:40 +0000 (GMT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1679586227; bh=fqcMKt1oBSR5L6Q8opsI63fwItnsnZyiV5drCHsNuLI=; h=Date:Cc:Subject:To:References:From:In-Reply-To:From; b=eNbPAtfwrGZFe7FIs6NljH+Y1y7/jks83wQi/OH9fQ0zixOK+wI9UClTwQVKgnOGr 19s+YgE9ZDx1bwb/p6VvFqAJ6+9pmfSO9CaE5q6VXmA0bA91I1S1c7EwTkNvDiUsk2 nNd22mJ30PPDaPc3iO+aBQxrgpIpCwI5rVZV2z8+2wccfYlXzhop17Rrxf0FyUUtuP qQ3nrOkV8K53MEiJGKaDU4YjuO9Ejv5ic9Yzdwi+7RZss6u97Mc+Sgpj2qVh7Akp8x m0RAN3N7TOqFKofqXaGy8nTgauWoeZKf5ABJ/GURFa9ahLP4PpXOO3s7PjE6LWpvQg HWq1+QR76EXzQ== Message-ID: <996c14d4-6dcc-7d14-cf76-d8fbea0a9040@collabora.com> Date: Thu, 23 Mar 2023 20:43:36 +0500 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.2 Cc: Muhammad Usama Anjum , David Hildenbrand , Andrew Morton , =?UTF-8?B?TWljaGHFgiBNaXJvc8WC?= =?UTF-8?Q?aw?= , Andrei Vagin , Danylo Mocherniuk , Paul Gofman , Cyrill Gorcunov , Mike Rapoport , Nadav Amit , Alexander Viro , Shuah Khan , Christian Brauner , Yang Shi , Vlastimil Babka , "Liam R . Howlett" , Yun Zhou , Suren Baghdasaryan , Alex Sierra , Matthew Wilcox , Pasha Tatashin , Axel Rasmussen , "Gustavo A . R . Silva" , Dan Williams , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Greg KH , kernel@collabora.com Subject: Re: [PATCH v11 1/7] userfaultfd: Add UFFD WP Async support Content-Language: en-US To: Peter Xu References: <20230309135718.1490461-1-usama.anjum@collabora.com> <20230309135718.1490461-2-usama.anjum@collabora.com> <1b78ee32-003d-5645-c223-619b66d41733@collabora.com> From: Muhammad Usama Anjum In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 4992FC0011 X-Rspam-User: X-Stat-Signature: f311i6qycnpp9515exzgrnyyrc6cjg6d X-HE-Tag: 1679586228-833108 X-HE-Meta: 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 tLOwYDEH 1r4eAlvDLZOv4NwdpGCxGUn5UF5W22+8SBqXSlvM7IKl/I7A4Azf1kGnMCzu6z6Sr4LgRVDrsCRs2dSYkRV0OFWgzNm1DYg8z52LXX+luS8n362XiMwBTUXqVuYWaz2UvJDZ8ckQ+SSP5G70v640RwUB49fiCpkGxblbbOqszm2JgdPgefCgx19kewwsQ3dZBhFw9HiNtVkwe0f5++8WDirbeY5659XnwJGpcqPzppzJ7rRFnrATGGOlNnFtpX9WhvxgrqVtke4COQpefOsV3eKHPQ3MGxHigEF9F9C0dSa0UMSk= 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: On 3/22/23 12:25 AM, Peter Xu wrote: > Hi, Muhammad, > > On Tue, Mar 21, 2023 at 05:21:15PM +0500, Muhammad Usama Anjum wrote: >> Thank you so much for the patch. I've tested hugetlb mem. This patch is >> working fine for hugetlb shmem: >> *shmid = shmget(2, size, SHM_HUGETLB | IPC_CREAT | SHM_R | SHM_W); >> mem = shmat(*shmid, 0, 0); >> >> I've found slight issue with hugetlb mem which has been mmaped: >> mem = mmap(NULL, size, PROT_READ | PROT_WRITE, >> MAP_ANONYMOUS | MAP_HUGETLB | MAP_PRIVATE, -1, 0); >> The issue is that even after witting to this memory, the wp flag is still >> present there and memory doesn't appear to be dirty when it should have >> been dirty. The temporary fix is to write to memory and write protect the >> memory one extra time. > > I looked into this today and found it's an existing bug that can trigger > with sync mode too.. as long as protection applied to unpopulated hugetlb > private mappings, then write to it. > > I've sent a fix for it here and have you copied: > > https://lore.kernel.org/linux-mm/20230321191840.1897940-1-peterx@redhat.com/T/#u > > Please have a look and see whether it also fixes your issue. Thanks for sending the patch. I've replied on the sent patch. > > PS: recently I added a warning in commit c2da319c2e2789 and that can indeed > capture this one when verifying using pagemap. I'd guess your dmesg should > also contain something dumped. I didn't had debug_vm config enabled. I've enabled it now. I'm getting only the following stack trace in failure scenario: ok 1 Hugetlb shmem testing: all new pages must not be written (dirty) 0 ok 2 Hugetlb shmem testing: all pages must be written (dirty) 1 512 0 512 ok 3 Hugetlb mem testing: all new pages must not be written (dirty) 0 [ 10.086540] ------------[ cut here ]------------ [ 10.087758] WARNING: CPU: 0 PID: 175 at arch/x86/include/asm/pgtable.h:313 pagemap_scan_hugetlb_entry+0x19c/0x230 [ 10.090208] Modules linked in: [ 10.091059] CPU: 0 PID: 175 Comm: pagemap_ioctl Not tainted 6.3.0-rc3-next-20230320-00010-gdc395ccf1882 #88 [ 10.093224] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-5 04/01/2014 [ 10.095879] RIP: 0010:pagemap_scan_hugetlb_entry+0x19c/0x230 [ 10.097497] Code: 89 ca 41 89 c2 29 c8 4c 01 c2 49 39 d2 41 0f 43 c0 e9 53 ff ff ff 48 83 e2 9f 89 c7 31 ed 49 89 d1 83 e7 02 0f 84 30 ff ff ff <0f> 0b 31 ff e9 27 ff ff ff 48 83 e2 9f 44 89 c0 bf 01 00 00 00 bd [ 10.102528] RSP: 0018:ffffb6cd80303d10 EFLAGS: 00010202 [ 10.104002] RAX: 8000000000000ce7 RBX: 00007fcc84000000 RCX: 0000000000200000 [ 10.105989] RDX: 80000002f7c00c87 RSI: 0000000000000001 RDI: 0000000000000002 [ 10.108043] RBP: 0000000000000000 R08: 0000000000000200 R09: 80000002f7c00c87 [ 10.110004] R10: ffffa08541e3220c R11: 0000000000000000 R12: ffffa08541562420 [ 10.112335] R13: ffffb6cd80303e70 R14: 00007fcc84000000 R15: ffffffff8eae1520 [ 10.114688] FS: 00007fcc8454b740(0000) GS:ffffa0886fc00000(0000) knlGS:0000000000000000 [ 10.116960] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 10.118187] CR2: 00007fcc84000000 CR3: 0000000102838000 CR4: 0000000000750ef0 [ 10.119628] PKRU: 55555554 [ 10.120184] Call Trace: [ 10.120730] [ 10.121206] __walk_page_range+0xbe/0x1b0 [ 10.122048] walk_page_range+0x15f/0x1a0 [ 10.122869] do_pagemap_cmd+0x239/0x390 [ 10.123672] __x64_sys_ioctl+0x8b/0xc0 [ 10.124462] do_syscall_64+0x3a/0x90 [ 10.125227] entry_SYSCALL_64_after_hwframe+0x72/0xdc [ 10.126326] RIP: 0033:0x7fcc8464bbab [ 10.127066] Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89> c2 3d 00 f0 ff ff 77 1c 48 8b 44 24 18 64 48 2b 04 25 28 00 00 [ 10.130868] RSP: 002b:00007fff9b864240 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 [ 10.132412] RAX: ffffffffffffffda RBX: 0000000000001000 RCX: 00007fcc8464bbab [ 10.133880] RDX: 00007fff9b8642c0 RSI: 00000000c0586610 RDI: 0000000000000003 [ 10.135328] RBP: 00007fff9b864320 R08: 0000000000000001 R09: 0000000000000000 [ 10.136790] R10: 00007fff9b864217 R11: 0000000000000246 R12: 0000000000000000 [ 10.138285] R13: 00007fff9b8644f8 R14: 0000000000409df0 R15: 00007fcc84862020 [ 10.139729] [ 10.140197] ---[ end trace 0000000000000000 ]--- not ok 4 Hugetlb mem testing: all pages must be written (dirty) 0 -2072900416 0 512 > > Thanks, > -- BR, Muhammad Usama Anjum