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Date:   Wed, 12 Jul 2023 18:48:37 -0700
From:   "Darrick J. Wong" <djwong@kernel.org>
To:     Mikulas Patocka <mpatocka@redhat.com>
Cc:     Eryu Guan <eguan@redhat.com>, Zorro Lang <zlang@kernel.org>,
        fstests@vger.kernel.org,
        Kent Overstreet <kent.overstreet@linux.dev>
Subject: Re: [PATCH] generic/558: limit the number of spawned subprocesses
Message-ID: <20230713014837.GG11442@frogsfrogsfrogs>
References: <2bb7705c-9a1a-6185-4554-9121e5cda710@redhat.com>
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Mikulas, does this solve the forkbomb problem?

--D

diff --git a/tests/generic/558 b/tests/generic/558
index 4e22ce656b..de5c28d00d 100755
--- a/tests/generic/558
+++ b/tests/generic/558
@@ -39,15 +39,21 @@ _scratch_mkfs_sized $((1024 * 1024 * 1024)) >>$seqres.full 2>&1
 _scratch_mount
 
 i=0
-free_inode=`_get_free_inode $SCRATCH_MNT`
-file_per_dir=1000
-loop=$((free_inode / file_per_dir + 1))
+free_inodes=$(_get_free_inode $SCRATCH_MNT)
+nr_cpus=$(( $($here/src/feature -o) * 4 * LOAD_FACTOR ))
+echo "free inodes: $free_inodes nr_cpus: $nr_cpus" >> $seqres.full
+
+if ((free_inodes <= nr_cpus)); then
+	nr_cpus=1
+	files_per_dir=$free_inodes
+else
+	files_per_dir=$(( (free_inodes + nr_cpus - 1) / nr_cpus ))
+fi
 mkdir -p $SCRATCH_MNT/testdir
 
 echo "Create $((loop * file_per_dir)) files in $SCRATCH_MNT/testdir" >>$seqres.full
-while [ $i -lt $loop ]; do
-	create_file $SCRATCH_MNT/testdir $file_per_dir $i >>$seqres.full 2>&1 &
-	let i=$i+1
+for ((i = 0; i < nr_cpus; i++)); do
+	create_file $SCRATCH_MNT/testdir $files_per_dir $i >>$seqres.full 2>&1 &
 done
 wait