Greetings! (If you are receiving this again, that's because I'm sending from another domain since my message from @gmx.fr was not forwarded to the lists.) With sched-Add-migrate_disable.patch first released in v5.9-rc8-rt14 [1] linux-rt defines functions migrate_disable and migrate_enable. They are used in linux headers in various macros and static inline functions, and in particular in kmap_atomic and kunmap_atomic. The latter are needed by ZFS which currently fails to build against 5.9-rt [2] because these functions are exported with EXPORT_SYMBOL_GPL. Could you export them with EXPORT_SYMBOL instead? I have checked that ZFS 2.0.0 builds and works with 5.9.1-rt20 (with an additional fix [3]) with this patch: --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -1812 +1812 @@ void migrate_disable(void) -EXPORT_SYMBOL_GPL(migrate_disable); +EXPORT_SYMBOL(migrate_disable); @@ -1843 +1843 @@ void migrate_enable(void) -EXPORT_SYMBOL_GPL(migrate_enable); +EXPORT_SYMBOL(migrate_enable); [1] https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git/diff/patches/0009-sched-Add-migrate_disable.patch?h=v5.9-rc8-rt14-patches&id=9a89bfdb3bc77aecdd0ff8cc69b595541c7b50c4 [2] https://github.com/openzfs/zfs/issues/11097#issuecomment-740682245 [3] https://github.com/openzfs/zfs/pull/11309