On Mon, 30 Oct 2023, Marek Marczykowski-Górecki wrote: > > Well, it would be possible that larger pages in a bio would trip e.g. bio > > splitting due to maximum segment size the disk supports (which can be e.g. > > 0xffff) and that upsets something somewhere. But this is pure > > speculation. We definitely need more debug data to be able to tell more. > > I can collect more info, but I need some guidance how :) Some patch > adding extra debug messages? > Note I collect those via serial console (writing to disk doesn't work > when it freezes), and that has some limits in the amount of data I can > extract especially when printed quickly. For example sysrq-t is too much. > Or maybe there is some trick to it, like increasing log_bug_len? If you can do more tests, I would suggest this: We already know that it works with order 3 and doesn't work with order 4. So, in the file include/linux/mmzone.h, change PAGE_ALLOC_COSTLY_ORDER from 3 to 4 and in the file drivers/md/dm-crypt.c leave "unsigned int order = PAGE_ALLOC_COSTLY_ORDER" there. Does it deadlock or not? So, that we can see whether the deadlock depends on PAGE_ALLOC_COSTLY_ORDER or whether it is just a coincidence. Mikulas
