| Message ID | 20240227044021.GT616564@frogsfrogsfrogs (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v1.1,1/8] generic/604: try to make race occur reliably | expand |
On Mon, Feb 26, 2024 at 08:40:21PM -0800, Darrick J. Wong wrote: > This test will occasionaly fail like so: > > --- /tmp/fstests/tests/generic/604.out 2024-02-03 12:08:52.349924277 -0800 > +++ /var/tmp/fstests/generic/604.out.bad 2024-02-05 04:35:55.020000000 -0800 > @@ -1,2 +1,5 @@ > QA output created by 604 > -Silence is golden > +mount: /opt: /dev/sda4 already mounted on /opt. > + dmesg(1) may have more information after failed mount system call. > +mount -o usrquota,grpquota,prjquota, /dev/sda4 /opt failed > +(see /var/tmp/fstests/generic/604.full for details) > > As far as I can tell, the cause of this seems to be _scratch_mount > getting forked and exec'd before the backgrounded umount process has a > chance to enter the kernel. When this occurs, the mount() system call > will return -EBUSY because this isn't an attempt to make a bind mount. > Slow things down slightly by stalling the mount by 10ms. > > Signed-off-by: Darrick J. Wong <djwong@kernel.org> > --- > v1.1: indent commit message, fix busted comment > --- Reviewed-by: Zorro Lang <zlang@redhat.com> > tests/generic/604 | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/tests/generic/604 b/tests/generic/604 > index cc6a4b214f..00da56dd70 100755 > --- a/tests/generic/604 > +++ b/tests/generic/604 > @@ -24,10 +24,12 @@ _scratch_mount > for i in $(seq 0 500); do > $XFS_IO_PROG -f -c "pwrite 0 4K" $SCRATCH_MNT/$i >/dev/null > done > -# For overlayfs, avoid unmouting the base fs after _scratch_mount > -# tries to mount the base fs > +# For overlayfs, avoid unmouting the base fs after _scratch_mount tries to > +# mount the base fs. Delay the mount attempt by a small amount in the hope > +# that the mount() call will try to lock s_umount /after/ umount has already > +# taken it. > $UMOUNT_PROG $SCRATCH_MNT & > -_scratch_mount > +sleep 0.01s ; _scratch_mount > wait > > echo "Silence is golden" >
On Mon, Feb 26, 2024 at 08:40:21PM -0800, Darrick J. Wong wrote: > This test will occasionaly fail like so: > > --- /tmp/fstests/tests/generic/604.out 2024-02-03 12:08:52.349924277 -0800 > +++ /var/tmp/fstests/generic/604.out.bad 2024-02-05 04:35:55.020000000 -0800 > @@ -1,2 +1,5 @@ > QA output created by 604 > -Silence is golden > +mount: /opt: /dev/sda4 already mounted on /opt. > + dmesg(1) may have more information after failed mount system call. > +mount -o usrquota,grpquota,prjquota, /dev/sda4 /opt failed > +(see /var/tmp/fstests/generic/604.full for details) > > As far as I can tell, the cause of this seems to be _scratch_mount > getting forked and exec'd before the backgrounded umount process has a > chance to enter the kernel. When this occurs, the mount() system call > will return -EBUSY because this isn't an attempt to make a bind mount. > Slow things down slightly by stalling the mount by 10ms. > > Signed-off-by: Darrick J. Wong <djwong@kernel.org> > --- > v1.1: indent commit message, fix busted comment > --- > tests/generic/604 | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/tests/generic/604 b/tests/generic/604 > index cc6a4b214f..00da56dd70 100755 > --- a/tests/generic/604 > +++ b/tests/generic/604 > @@ -24,10 +24,12 @@ _scratch_mount > for i in $(seq 0 500); do > $XFS_IO_PROG -f -c "pwrite 0 4K" $SCRATCH_MNT/$i >/dev/null > done > -# For overlayfs, avoid unmouting the base fs after _scratch_mount > -# tries to mount the base fs > +# For overlayfs, avoid unmouting the base fs after _scratch_mount tries to s/unmouting/unmounting/ ?
On Tue, Feb 27, 2024 at 06:52:21AM -0800, Christoph Hellwig wrote: > On Mon, Feb 26, 2024 at 08:40:21PM -0800, Darrick J. Wong wrote: > > This test will occasionaly fail like so: > > > > --- /tmp/fstests/tests/generic/604.out 2024-02-03 12:08:52.349924277 -0800 > > +++ /var/tmp/fstests/generic/604.out.bad 2024-02-05 04:35:55.020000000 -0800 > > @@ -1,2 +1,5 @@ > > QA output created by 604 > > -Silence is golden > > +mount: /opt: /dev/sda4 already mounted on /opt. > > + dmesg(1) may have more information after failed mount system call. > > +mount -o usrquota,grpquota,prjquota, /dev/sda4 /opt failed > > +(see /var/tmp/fstests/generic/604.full for details) > > > > As far as I can tell, the cause of this seems to be _scratch_mount > > getting forked and exec'd before the backgrounded umount process has a > > chance to enter the kernel. When this occurs, the mount() system call > > will return -EBUSY because this isn't an attempt to make a bind mount. > > Slow things down slightly by stalling the mount by 10ms. > > > > Signed-off-by: Darrick J. Wong <djwong@kernel.org> > > --- > > v1.1: indent commit message, fix busted comment > > --- > > tests/generic/604 | 8 +++++--- > > 1 file changed, 5 insertions(+), 3 deletions(-) > > > > diff --git a/tests/generic/604 b/tests/generic/604 > > index cc6a4b214f..00da56dd70 100755 > > --- a/tests/generic/604 > > +++ b/tests/generic/604 > > @@ -24,10 +24,12 @@ _scratch_mount > > for i in $(seq 0 500); do > > $XFS_IO_PROG -f -c "pwrite 0 4K" $SCRATCH_MNT/$i >/dev/null > > done > > -# For overlayfs, avoid unmouting the base fs after _scratch_mount > > -# tries to mount the base fs > > +# For overlayfs, avoid unmouting the base fs after _scratch_mount tries to > > s/unmouting/unmounting/ ? Sure, I've changed that when I merged it. Thanks for pointing out that. > >
diff --git a/tests/generic/604 b/tests/generic/604 index cc6a4b214f..00da56dd70 100755 --- a/tests/generic/604 +++ b/tests/generic/604 @@ -24,10 +24,12 @@ _scratch_mount for i in $(seq 0 500); do $XFS_IO_PROG -f -c "pwrite 0 4K" $SCRATCH_MNT/$i >/dev/null done -# For overlayfs, avoid unmouting the base fs after _scratch_mount -# tries to mount the base fs +# For overlayfs, avoid unmouting the base fs after _scratch_mount tries to +# mount the base fs. Delay the mount attempt by a small amount in the hope +# that the mount() call will try to lock s_umount /after/ umount has already +# taken it. $UMOUNT_PROG $SCRATCH_MNT & -_scratch_mount +sleep 0.01s ; _scratch_mount wait echo "Silence is golden"
This test will occasionaly fail like so: --- /tmp/fstests/tests/generic/604.out 2024-02-03 12:08:52.349924277 -0800 +++ /var/tmp/fstests/generic/604.out.bad 2024-02-05 04:35:55.020000000 -0800 @@ -1,2 +1,5 @@ QA output created by 604 -Silence is golden +mount: /opt: /dev/sda4 already mounted on /opt. + dmesg(1) may have more information after failed mount system call. +mount -o usrquota,grpquota,prjquota, /dev/sda4 /opt failed +(see /var/tmp/fstests/generic/604.full for details) As far as I can tell, the cause of this seems to be _scratch_mount getting forked and exec'd before the backgrounded umount process has a chance to enter the kernel. When this occurs, the mount() system call will return -EBUSY because this isn't an attempt to make a bind mount. Slow things down slightly by stalling the mount by 10ms. Signed-off-by: Darrick J. Wong <djwong@kernel.org> --- v1.1: indent commit message, fix busted comment --- tests/generic/604 | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-)