** Description changed:
[Impact]
On arm64 with PREEMPTION and BLK_CGROUP enabled,
preempt_schedule_notrace is being pulled in which is a GPL-only function
so the DKMS build fails:
DKMS make.log for zfs-0.8.3 for kernel 5.4.0-1015-raspi (aarch64)
Tue Aug 18 06:30:17 UTC 2020
./scripts/make_gitrev.sh
/bin/bash: ./scripts/make_gitrev.sh: No such file or directory
make: [Makefile:1512: gitrev] Error 127 (ignored)
make all-recursive
make[1]: Entering directory '/var/lib/dkms/zfs/0.8.3/build'
Making all in module
make[2]: Entering directory '/var/lib/dkms/zfs/0.8.3/build/module'
list='icp lua'; for targetdir in $list; do \
make -C $targetdir; \
done
make[3]: Entering directory '/var/lib/dkms/zfs/0.8.3/build/module/icp'
mkdir -p api core spi io os algs algs/aes algs/edonr algs/modes algs/sha1
algs/sha2 algs/skein asm-x86_64 asm-x86_64/aes asm-x86_64/modes asm-x86_64/sha1
asm-x86_64/sha2 asm-i386 asm-generic
make[3]: Leaving directory '/var/lib/dkms/zfs/0.8.3/build/module/icp'
make[3]: Entering directory '/var/lib/dkms/zfs/0.8.3/build/module/lua'
mkdir -p setjmp
make[3]: Leaving directory '/var/lib/dkms/zfs/0.8.3/build/module/lua'
make -C /lib/modules/5.4.0-1015-raspi/build M=`pwd` CONFIG_ZFS=m modules
make[3]: Entering directory '/usr/src/linux-headers-5.4.0-1015-raspi'
CC [M] /var/lib/dkms/zfs/0.8.3/build/module/avl/avl.o
CC [M] /var/lib/dkms/zfs/0.8.3/build/module/nvpair/nvpair.o
<SNIP>
CC [M] /var/lib/dkms/zfs/0.8.3/build/module/zfs/qat_compress.o
CC [M] /var/lib/dkms/zfs/0.8.3/build/module/zfs/qat_crypt.o
CC [M]
/var/lib/dkms/zfs/0.8.3/build/module/zfs/vdev_raidz_math_aarch64_neon.o
CC [M]
/var/lib/dkms/zfs/0.8.3/build/module/zfs/vdev_raidz_math_aarch64_neonx2.o
LD [M] /var/lib/dkms/zfs/0.8.3/build/module/zfs/zfs.o
Building modules, stage 2.
MODPOST 8 modules
FATAL: modpost: GPL-incompatible module zfs.ko uses GPL-only symbol
'preempt_schedule_notrace'
make[4]: *** [scripts/Makefile.modpost:94: __modpost] Error 1
make[3]: *** [Makefile:1647: modules] Error 2
make[3]: Leaving directory '/usr/src/linux-headers-5.4.0-1015-raspi'
make[2]: *** [Makefile:30: modules] Error 2
make[2]: Leaving directory '/var/lib/dkms/zfs/0.8.3/build/module'
make[1]: *** [Makefile:807: all-recursive] Error 1
make[1]: Leaving directory '/var/lib/dkms/zfs/0.8.3/build'
make: *** [Makefile:676: all] Error 2
Note that Ubuntu currently doesn't support/provide a preemptible arm64
kernel so this hasn't been a problem so far.
[Test Case]
Install zfs-dkms on an arm64 system that has a PREEMPT kernel installed.
[Fix]
Redefine preempt_schedule_notrace() to preempt_schedule() in the ZFS
module (only for arm64 and if PREEMPTION and BLK_CGROUP are both
enabled). preempt_schedule() is not a GPL symbol.
[Regression Potential]
Per comment in the kernel source, preempt_schedule_notrace() is required
- when tracing is enabled. As long as tracing is disabled, this 'fix'
- should not cause any problems. Problems due to this change would
- manifest themselves as TBD.
+ when tracing is enabled. As long as tracing is not enabled, this 'fix'
+ should not cause any issues. Problems due to this change could show up
+ as kernel splats like:
+
+ ===============================
+ [ INFO: suspicious RCU usage. ]
+ 3.10.0-rc2+ #1 Not tainted
+ -------------------------------
+ include/linux/rcupdate.h:771 rcu_read_lock() used illegally while idle!
+ other info that might help us debug this:
+ RCU used illegally from idle CPU! rcu_scheduler_active = 1, debug_locks
= 0
+ RCU used illegally from extended quiescent state!
+ 2 locks held by cc1/63645:
+ #0: (&rq->lock){-.-.-.}, at: [<ffffffff816b39fd>] __schedule+0xed/0x9b0
+ #1: (rcu_read_lock){.+.+..}, at: [<ffffffff8109d645>]
cpuacct_charge+0x5/0x1f0
+
+ CPU: 1 PID: 63645 Comm: cc1 Not tainted 3.10.0-rc2+ #1 [loadavg: 40.57
27.55 13.39 25/277 64369]
+ Hardware name: Gigabyte Technology Co., Ltd.
GA-MA78GM-S2H/GA-MA78GM-S2H, BIOS F12a 04/23/2010
+ 0000000000000000 ffff88010f78fcf8 ffffffff816ae383 ffff88010f78fd28
+ ffffffff810b698d ffff88011c092548 000000000023d073 ffff88011c092500
+ 0000000000000001 ffff88010f78fd60 ffffffff8109d7c5 ffffffff8109d645
+ Call Trace:
+ [<ffffffff816ae383>] dump_stack+0x19/0x1b
+ [<ffffffff810b698d>] lockdep_rcu_suspicious+0xfd/0x130
+ [<ffffffff8109d7c5>] cpuacct_charge+0x185/0x1f0
+ [<ffffffff8109d645>] ? cpuacct_charge+0x5/0x1f0
+ [<ffffffff8108dffc>] update_curr+0xec/0x240
+ [<ffffffff8108f528>] put_prev_task_fair+0x228/0x480
+ [<ffffffff816b3a71>] __schedule+0x161/0x9b0
+ [<ffffffff816b4721>] preempt_schedule+0x51/0x80
+ [<ffffffff816b4800>] ? __cond_resched_softirq+0x60/0x60
+ [<ffffffff816b6824>] ? retint_careful+0x12/0x2e
+ [<ffffffff810ff3cc>] ftrace_ops_control_func+0x1dc/0x210
+ [<ffffffff816be280>] ftrace_call+0x5/0x2f
+ [<ffffffff816b681d>] ? retint_careful+0xb/0x2e
+ [<ffffffff816b4805>] ? schedule_user+0x5/0x70
+ [<ffffffff816b4805>] ? schedule_user+0x5/0x70
+ [<ffffffff816b6824>] ? retint_careful+0x12/0x2e
+ ------------[ cut here ]------------
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https://bugs.launchpad.net/bugs/1892001
Title:
zfs-dkms fails to build on arm64 with PREEMPTION and BLK_CGROUP
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