Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751022AbdHaG5X (ORCPT ); Thu, 31 Aug 2017 02:57:23 -0400 Received: from mx1.redhat.com ([209.132.183.28]:52770 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750757AbdHaG5W (ORCPT ); Thu, 31 Aug 2017 02:57:22 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com DB4D1C058EAF Authentication-Results: ext-mx08.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx08.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=xzhou@redhat.com Date: Thu, 31 Aug 2017 14:57:15 +0800 From: Xiong Zhou To: Amir Goldstein Cc: Xiong Zhou , linux-fsdevel , linux-kernel , Jan Kara Subject: Re: fanotify_mark FAN_MARK_FLUSH | _MOUNT stress blocks write to directory Message-ID: <20170831065715.y66ilho4g4azpl7n@XZHOUW.usersys.redhat.com> References: <20170831035137.hg6arnj2lq5lcmri@XZHOUW.usersys.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170714-19-95cc18 (1.8.3) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.32]); Thu, 31 Aug 2017 06:57:22 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6104 Lines: 178 On Thu, Aug 31, 2017 at 07:52:41AM +0300, Amir Goldstein wrote: > On Thu, Aug 31, 2017 at 6:51 AM, Xiong Zhou wrote: > > hi, > > > > This happens on 4.13.0-rc7+ to commit 42ff72c > > Don't understand. Is this a regression? from which commit? No. I'm just saying the exact kernel version: Linus tree, commit 42ff72c The same on 4.11. Did not test on kernels older than that. > > > > > After firing up the stress, touch a file in monitoring directory could > > hang like forever. > > > > Pretty easy to hit. > > So are running 3 processes that constantly ask to be notified > blocking on file system events and then they never read those > events. Even tough the marks are also destroyed, odd are that > at least one mark will be alive at any given time. > > Why is it surprising that touching a file in monitored directory > hangs forever? It should complete with an error or success in a reasonable time ? If we keep it hanging, oom killer is online and system hangs. > > I am very happy to see someone is writing stress tests for > fanotify, I am just not sure this test is tuned correctly. > Have you been trying to reproduce a reported bug? No. Just try stress tests. Xiong > > Amir. > > > > > Thanks, > > Xiong > > > > [ 492.060879] INFO: task touch:2259 blocked for more than 120 seconds. > > [ 492.093497] Not tainted 4.13.0-rc7-master-42ff72c+ #9 > > [ 492.121049] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > > [ 492.156289] touch D 0 2259 2233 0x00000080 > > [ 492.180880] Call Trace: > > [ 492.191813] __schedule+0x28d/0x890 > > [ 492.207440] schedule+0x36/0x80 > > [ 492.221529] fanotify_handle_event+0x2a1/0x2f0 > > [ 492.241542] ? remove_wait_queue+0x60/0x60 > > [ 492.260150] fsnotify+0x2d3/0x4f0 > > [ 492.275055] ? security_inode_init_security+0xd2/0x190 > > [ 492.298097] security_file_open+0x89/0x90 > > [ 492.316038] do_dentry_open+0x139/0x330 > > [ 492.333216] vfs_open+0x4f/0x70 > > [ 492.347225] ? may_open+0x5a/0x100 > > [ 492.362481] path_openat+0x548/0x13b0 > > [ 492.378958] do_filp_open+0x91/0x100 > > [ 492.394969] ? __alloc_fd+0x46/0x170 > > [ 492.410930] do_sys_open+0x124/0x210 > > [ 492.426927] SyS_open+0x1e/0x20 > > [ 492.440963] do_syscall_64+0x67/0x150 > > [ 492.457367] entry_SYSCALL64_slow_path+0x25/0x25 > > [ 492.478251] RIP: 0033:0x7fe877f8e5a0 > > [ 492.495755] RSP: 002b:00007ffe57120318 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 > > [ 492.529911] RAX: ffffffffffffffda RBX: 00007ffe57120578 RCX: 00007fe877f8e5a0 > > [ 492.561508] RDX: 00000000000001b6 RSI: 0000000000000941 RDI: 00007ffe5712268c > > [ 492.595577] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > > [ 492.631144] R10: 00007ffe57120030 R11: 0000000000000246 R12: 00007ffe5712268c > > [ 492.664970] R13: 00007fe8782612a0 R14: 0000000000000001 R15: 0000000000000000 > > > > > > -------------------------------- > > $ cat test.sh > > > > #!/bin/bash -x > > > > fallocate -l 2G test.img > > mkfs.xfs -fq test.img > > mkdir -p testdir > > mount -o loop test.img testdir || exit > > > > SCRATCH_MNT=$(readlink -f testdir) > > > > function clean () > > { > > while ps -eo comm | grep -q -e fanotify ; do > > killall fanotify_flush_stress > > done > > > > umount -d $SCRATCH_MNT > > rm -rf test.img scrc $SCRATCH_MNT fanotify_flush_stress > > } > > > > trap "clean; exit;" 2 > > > > cc fanotify_flush_stress.c -o fanotify_flush_stress > > > > ./fanotify_flush_stress $SCRATCH_MNT & > > ./fanotify_flush_stress $SCRATCH_MNT & > > ./fanotify_flush_stress $SCRATCH_MNT & > > > > ps jf | grep fanotify > > > > touch $SCRATCH_MNT/1 # hang > > > > clean > > > > -------------------------------- > > $ cat fanotify_flush_stress.c > > > > #define _GNU_SOURCE /* Needed to get O_LARGEFILE definition */ > > #include > > #include > > #include > > #include > > #include > > #include > > #include > > #include > > #include > > > > int main(int argc, char *argv[]) > > { > > char buf; > > int fd; > > > > /* Check mount point is supplied */ > > if (argc != 2) { > > fprintf(stderr, "Usage: %s MOUNT\n", argv[0]); > > exit(EXIT_FAILURE); > > } > > > > printf("%s on %s\n", argv[0], argv[1]); > > /* Create the file descriptor for accessing the fanotify API */ > > fd = fanotify_init(FAN_CLOEXEC | FAN_CLASS_CONTENT | FAN_NONBLOCK, > > O_RDWR | O_LARGEFILE); > > if (fd == -1) { > > perror("fanotify_init"); > > exit(EXIT_FAILURE); > > } > > > > /* Loop marking all kinds of events and flush */ > > while (1) { > > > > #if 1 > > if (fanotify_mark(fd, FAN_MARK_ADD | FAN_MARK_MOUNT, > > FAN_ACCESS | FAN_MODIFY | FAN_OPEN_PERM | FAN_CLOSE | > > FAN_OPEN | FAN_ACCESS_PERM | FAN_ONDIR | > > FAN_EVENT_ON_CHILD, -1, argv[1]) == -1) > > > > perror("fanotify_mark add"); > > > > if (fanotify_mark(fd, FAN_MARK_FLUSH | FAN_MARK_MOUNT, > > 0, -1, argv[1]) == -1) > > perror("fanotify_mark flush mount"); > > #else > > if (fanotify_mark(fd, FAN_MARK_ADD | FAN_MARK_MOUNT, > > FAN_ACCESS | FAN_MODIFY | FAN_OPEN_PERM | FAN_CLOSE | > > FAN_OPEN | FAN_ACCESS_PERM | FAN_ONDIR | > > FAN_EVENT_ON_CHILD, -1, argv[1]) == -1) > > > > perror("fanotify_mark add"); > > > > if (fanotify_mark(fd, FAN_MARK_FLUSH, 0, -1, argv[1]) == -1) > > perror("fanotify_mark flush"); > > #endif > > } > > > > close(fd); > > exit(EXIT_SUCCESS); > > }