Hi On Mon, 26 Mar 2012, mittals@xxxxxxxxxxxxxx wrote: > Hi, > > We are using dm-crypt driver to encrypt Android Phone on a 2 core target. > We saw random failures (kernel panics) in scatterwalk code when we were > trying to bring secondary cpu online and offline randomly. > > I looked into the dm-crypt driver(drivers/md/dm-crypt.c) and put a hack in > the kcryptd_queue_crypt function to acquire hotplug lock (using > get_online_cpus()), just before adding new work in work queue and release > this lock (using put_online_cpus) after completing work in kcryptd_crypt > function. > With this i didn't see any issue during encryption. > > So my questions are - > > 1) Is it a know problem that there is some issue with dm-crypt driver with > cpu hotplug? Yes it is a known problem. Not only dm-crypt is affected, there are other kernel parts that can crash too, see: http://www.redhat.com/archives/dm-devel/2012-March/msg00035.html > 2) If yes, then can someone suggest me a cleaner way to resolve this issue? Another possible solution is to flush dm-crypt workqueues in an unplug hook. Another possible solution is to use these patches: http://people.redhat.com/mpatocka/patches/kernel/dm-crypt-paralelizace/current/ --- they add paralelization to dm-crypt and as a side effect, they remove the dm-crypt bug. You can actually use only the first five patches: dm-crypt-fix-mempool-deadlock.patch, dm-crypt-test-error.patch, dm-crypt-rename-pending.patch, dm-crypt-global-static-cipher-data.patch, dm-crypt-remove-percpu.patch. But, as a general solution, I'd recommend to not use CPU unplug at all. There are other kernel parts that have the same bug as dm-crypt and it is not trivial to find them. Mikulas > Thanks in advance! > > --Shashank > > Sent by an employee of the Qualcomm Innovation Center, Inc. > The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum. > > -- > dm-devel mailing list > dm-devel@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/dm-devel > -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
