From patchwork Tue Jun 11 03:02:02 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Luis Chamberlain X-Patchwork-Id: 13692779 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5584F7E782; Tue, 11 Jun 2024 03:02:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718074928; cv=none; b=ROs3dgX+BQ9Iydqlr3WEgOn7LED6Rs8HxbWWevRaorLLjmOvAA+FdDzwCQkU3hz+1zehcue/xXBzm3O/N8TOnDSxa4oUjLIUM6NL0Jlh29+Xe51L4AJe4iqLKh3ALyeu73OxIGadAMZBhMlxk0ss09NgfukR6OGTljv2Nn3Gk4E= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718074928; c=relaxed/simple; bh=0UFPifbtnr1gSnowkmHbNZZMQdlAKHV/k6/w1U/2hfM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mdB1BgPf2GYi9RPnFLlKxQODCVBTqOK10AhuAbGYiHkqb/h8YjcBc50fTjdhXVhw0m6RXxwIFE8/cqDRvUqapemsl531ugKe+M2dKMOmhqZ0LJPCMbJ4aQ5Y4SDCpFzF7Isvmm7RFFfLETUZ+2uzneH2IUng7qNT6bL8WLUi3LI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=tyK80xDR; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="tyK80xDR" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; h=Sender:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description; bh=w5upqqK3le9bkA35Adh9sB0Tb3TWHmZ5mS+iqjEKnts=; b=tyK80xDR4FjkmXamvnGufFwee/ osrHpUf1HtQ7JnZlKRPjDbwP6VxoRLDshUf1idmTDgzPQ+o+IBHMJw4lIaXvBME2ey/SQOv4qJHE0 VoOAOYx1Dw7Xetp3OUDD8IhANx6OsQV38M5S+ialE3F3kBNW+2cWU/ynh9I7FtSqdx20fyr9ly/b/ JdZmLCHGKzswNupQYtEkfjAcNXED2JcUObhdgPkEmjgLTSmJm+An6HmkF8VY9B/DICy229Ek8ILcP /j/RAriVVoSgBiq96+VcYOrrOuvfIOEv2Q5UTveYEUa60fNtFjy28iq9i34Wl6bN+8AWd/CaiRwqx BaXeOayw==; Received: from mcgrof by bombadil.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1sGrls-00000007DDO-2Yy9; Tue, 11 Jun 2024 03:02:04 +0000 From: Luis Chamberlain To: patches@lists.linux.dev, fstests@vger.kernel.org Cc: linux-xfs@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org, ziy@nvidia.com, vbabka@suse.cz, seanjc@google.com, willy@infradead.org, david@redhat.com, hughd@google.com, linmiaohe@huawei.com, muchun.song@linux.dev, osalvador@suse.de, p.raghav@samsung.com, da.gomez@samsung.com, hare@suse.de, john.g.garry@oracle.com, mcgrof@kernel.org Subject: [PATCH 5/5] fstests: add stress truncation + writeback test Date: Mon, 10 Jun 2024 20:02:02 -0700 Message-ID: <20240611030203.1719072-6-mcgrof@kernel.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240611030203.1719072-1-mcgrof@kernel.org> References: <20240611030203.1719072-1-mcgrof@kernel.org> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Sender: Luis Chamberlain Stress test folio splits by using the new debugfs interface to a target a new smaller folio order while triggering writeback at the same time. This is known to only creates a crash with min order enabled, so for example with a 16k block sized XFS test profile, an xarray fix for that is merged already. This issue is fixed by kernel commit 2a0774c2886d ("XArray: set the marks correctly when splitting an entry"). If inspecting more closely, you'll want to enable on your kernel boot: dyndbg='file mm/huge_memory.c +p' Since we want to race large folio splits we also augment the full test output log $seqres.full with the test specific number of successful splits from vmstat thp_split_page and thp_split_page_failed. The larger the vmstat thp_split_page the more we stress test this path. This test reproduces a really hard to reproduce crash immediately. Signed-off-by: Luis Chamberlain --- common/rc | 14 +++++ tests/generic/751 | 127 ++++++++++++++++++++++++++++++++++++++++++ tests/generic/751.out | 2 + 3 files changed, 143 insertions(+) create mode 100755 tests/generic/751 create mode 100644 tests/generic/751.out diff --git a/common/rc b/common/rc index 30beef4e5c02..60f572108818 100644 --- a/common/rc +++ b/common/rc @@ -158,6 +158,20 @@ _require_vm_compaction() _notrun "Need compaction enabled CONFIG_COMPACTION=y" fi } + +# Requires CONFIG_DEBUGFS and truncation knobs +_require_split_debugfs() +{ + if [ ! -f $DEBUGFS_MNT/split_huge_pages ]; then + _notrun "Needs CONFIG_DEBUGFS and split_huge_pages" + fi +} + +_split_huge_pages_all() +{ + echo 1 > $DEBUGFS_MNT/split_huge_pages +} + # Get hugepagesize in bytes _get_hugepagesize() { diff --git a/tests/generic/751 b/tests/generic/751 new file mode 100755 index 000000000000..7cc96054a5a9 --- /dev/null +++ b/tests/generic/751 @@ -0,0 +1,127 @@ +#! /bin/bash +# SPDX-License-Identifier: GPL-2.0 +# Copyright (C) 2024 Luis Chamberlain. All Rights Reserved. +# +# FS QA Test No. 751 +# +# stress page cache truncation + writeback +# +# This aims at trying to reproduce a difficult to reproduce bug found with +# min order. The issue was root caused to an xarray bug when we split folios +# to another order other than 0. This functionality is used to support min +# order. The crash: +# +# https://gist.github.com/mcgrof/d12f586ec6ebe32b2472b5d634c397df +# +# This may also find future truncation bugs in the future, as truncating any +# mapped file through the collateral of using echo 1 > split_huge_pages will +# always respect the min order. Truncating to a larger order then is excercised +# when this test is run against any filesystem LBS profile or an LBS device. +# +# If you're enabling this and want to check underneath the hood you may want to +# enable: +# +# dyndbg='file mm/huge_memory.c +p' +# +# This tests aims at increasing the rate of successful truncations so we want +# to increase the value of thp_split_page in $seqres.full. Using echo 1 > +# split_huge_pages is extremely aggressive, and even accounts for anonymous +# memory on a system, however we accept that tradeoff for the efficiency of +# doing the work in-kernel for any mapped file too. Our general goal here is to +# race with folio truncation + writeback. + +. ./common/preamble + +_begin_fstest auto long_rw stress soak smoketest + +# Override the default cleanup function. +_cleanup() +{ + cd / + rm -f $tmp.* + rm -f $runfile + kill -9 $split_huge_pages_files_pid > /dev/null 2>&1 +} + +fio_config=$tmp.fio +fio_out=$tmp.fio.out + +# real QA test starts here +_supported_fs generic +_require_test +_require_scratch +_require_debugfs +_require_split_debugfs +_require_command "$KILLALL_PROG" "killall" +_fixed_by_git_commit kernel 2a0774c2886d \ + "XArray: set the marks correctly when splitting an entry" + +# we need buffered IO to force truncation races with writeback in the +# page cache +cat >$fio_config <>$seqres.full 2>&1 +_scratch_mount >> $seqres.full 2>&1 + +# used to let our loops know when to stop +runfile="$tmp.keep.running.loop" +touch $runfile + +# The background ops are out of bounds, the goal is to race with fsstress. + +# Force folio split if possible, this seems to be screaming for MADV_NOHUGEPAGE +# for large folios. +while [ -e $runfile ]; do + _split_huge_pages_all >/dev/null 2>&1 +done & +split_huge_pages_files_pid=$! + +split_count_before=0 +split_count_failed_before=0 + +if grep -q thp_split_page /proc/vmstat; then + split_count_before=$(grep ^thp_split_page /proc/vmstat | head -1 | awk '{print $2}') + split_count_failed_before=$(grep ^thp_split_page_failed /proc/vmstat | head -1 | awk '{print $2}') +else + echo "no thp_split_page in /proc/vmstat" >> $seqres.full +fi + +# we blast away with large writes to force large folio writes when +# possible. +echo -e "Running fio with config:\n" >> $seqres.full +cat $fio_config >> $seqres.full +$FIO_PROG $fio_config --alloc-size=$(( $(nproc) * 8192 )) --output=$fio_out + +rm -f $runfile + +wait > /dev/null 2>&1 + +if grep -q thp_split_page /proc/vmstat; then + split_count_after=$(grep ^thp_split_page /proc/vmstat | head -1 | awk '{print $2}') + split_count_failed_after=$(grep ^thp_split_page_failed /proc/vmstat | head -1 | awk '{print $2}') + thp_split_page=$((split_count_after - split_count_before)) + thp_split_page_failed=$((split_count_failed_after - split_count_failed_before)) + + echo "vmstat thp_split_page: $thp_split_page" >> $seqres.full + echo "vmstat thp_split_page_failed: $thp_split_page_failed" >> $seqres.full +fi + +status=0 +exit diff --git a/tests/generic/751.out b/tests/generic/751.out new file mode 100644 index 000000000000..6479fa6f1404 --- /dev/null +++ b/tests/generic/751.out @@ -0,0 +1,2 @@ +QA output created by 751 +Silence is golden