On Tue, 11 Jul 2023, Darrick J. Wong wrote: > On Tue, Jul 11, 2023 at 05:51:42PM +0200, Mikulas Patocka wrote: > > When I run the test 558 on bcachefs, it works like a fork-bomb and kills > > the machine. The reason is that the "while" loop spawns "create_file" > > subprocesses faster than they are able to complete. > > > > This patch fixes the crash by limiting the number of subprocesses to 128. > > > > Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx> > > > > --- > > tests/generic/558 | 1 + > > 1 file changed, 1 insertion(+) > > > > Index: xfstests-dev/tests/generic/558 > > =================================================================== > > --- xfstests-dev.orig/tests/generic/558 > > +++ xfstests-dev/tests/generic/558 > > @@ -48,6 +48,7 @@ echo "Create $((loop * file_per_dir)) fi > > while [ $i -lt $loop ]; do > > create_file $SCRATCH_MNT/testdir $file_per_dir $i >>$seqres.full 2>&1 & > > let i=$i+1 > > + if [ $((i % 128)) = 0 ]; then wait; fi > > Hm. $loop is (roughly) the number of free inodes divided by 1000. This > test completes nearly instantly on XFS; how many free inodes does > bcachefs report after _scratch_mount? > > XFS reports ~570k inodes, so it's "only" starting 570 processes. > > I think it's probably wise to clamp $loop to something sane, but let's > get to the bottom of how the math went wrong and we got a forkbomb. > > --D bcachefs reports 14509106 total inodes (for a 1GB filesystem) As the test proceeds, the number of total inodes (as well as the number of free inodes) decreases. Mikulas
