On Thu, Oct 21, 2021 at 10:18:47AM -0700, Luis Chamberlain wrote: > On Thu, Oct 21, 2021 at 08:39:05AM +0800, Ming Lei wrote: > > On Wed, Oct 20, 2021 at 08:48:04AM -0700, Luis Chamberlain wrote: > > > A second series of tests is hitting CTRL-C on either randonly and > > > restarting testing once again randomly. > > > > ltp/zram02.sh has cleanup handler via trap to clean everything(swapoff/umount/reset/ > > rmmod), ctrl-c will terminate current forground task and cause shell to run the > > cleanup handler first, but further 'ctrl-c' will terminate the cleanup handler, > > then the cleanup won't be done completely, such as zram disk is left as swap > > device and zram can't be unloaded. The idea can be observed via the following > > script: > > > > #!/bin/bash > > trap 'echo "enter trap"; sleep 20; echo "exit trap";' INT > > sleep 30 > > > > After the above script is run foreground, when 1st ctrl-c is pressed, 'sleep 30' > > is terminated, then the trap command is run, so you can see "enter trap" > > dumped. Then if you pressed 2nd ctrl-c, 'sleep 20' is terminated immediately. > > So 'swapoff' from zram02.sh's trap function can be terminated in this way. > > > > zram disk being left as swap disk can be observed with your patch too > > after terminating via multiple ctrl-c which has to be done this way because > > the test is dead loop. > > > > So it is hard to cleanup everything completely after multiple 'CTRL-C' is > > involved, and it should be impossible. It needs violent multiple ctrl-c to > > terminate the dealoop test. > > > > So it isn't reasonable to expect that zram can be always unloaded successfully > > after the test script is terminated via multiple ctrl-c. > > For the life of me, I do not run into these issue with my patch. But > with yours I had. > > To be clear, I run zram02.sh on two terminals. Then to interrupt I just leave > CTRL-C pressed to issue multiple terminations until the script is done > on each terminal at a time, until I see both have completed. > > I repeat the same test, noting always that when I start one one terminal > the test is succeeding. And also when I cancel completely one script the > test continue fine without issue. As I explained wrt. shell's trap, this issue won't be avoided from userspace because trap function can be terminated by ctrl-c too, otherwise one shell script may not be terminated at all. The unclean shutdown can be observed in single 'while true; do zram02.sh; done' too on both your patches and mine. Also it is insane to write write test in a deadloop, and people seldom do that, not see such way in either blktests/xfstests. I you limit completion time of this test in long enough time(one or several hours) or big enough loops, I believe it can be done cleanly, such as: cnt=0 MAX=10000 while [ $cnt -lt $MAX ]; do PATH=$PATH:$PWD:$PWD/../../../lib/ ./zram02.sh; done Thanks, Ming
