Qu,

  fstests ran fine on an aarch64 kvm with this patch set.

  Further, I was running few hand tests as below, and it fails
  with - Unable to handle kernel paging.

  Test case looks something like..

  On x86_64 create btrfs on a file 11g
  copy /usr into /test-mnt stops at enospc
  set compression property on the root sunvol
  run defrag with -czstd
  truncate a large file 4gb
  punch holes on it
  truncate couple of smaller files
  unmount
  send file to an aarch64 (64k pagesize) kvm
  mount -o ro
  run sha256sum on all the files

---------------------
[37012.027764] BTRFS warning (device loop0): csum failed root 5 ino 611 
off 228659200 csum 0x1dcefc2d expected csum 0x69412d2a mirror 1
[37012.030971] BTRFS error (device loop0): bdev /dev/loop0 errs: wr 0, 
rd 0, flush 0, corrupt 9, gen 0
[37012.036223] BTRFS warning (device loop0): csum failed root 5 ino 616 
off 228724736 csum 0x73f63661 expected csum 0xaf922a6f mirror 1
[37012.036250] BTRFS error (device loop0): bdev /dev/loop0 errs: wr 0, 
rd 0, flush 0, corrupt 10, gen 0
[37012.123917] Unable to handle kernel paging request at virtual address 
0061d1f66c080000
[37012.126104] Mem abort info:
[37012.126951]   ESR = 0x96000004
[37012.127791]   EC = 0x25: DABT (current EL), IL = 32 bits
[37012.129207]   SET = 0, FnV = 0
[37012.130043]   EA = 0, S1PTW = 0
[37012.131269] Data abort info:
[37012.132165]   ISV = 0, ISS = 0x00000004
[37012.133211]   CM = 0, WnR = 0
[37012.134014] [0061d1f66c080000] address between user and kernel 
address ranges
[37012.136050] Internal error: Oops: 96000004 [#1] PREEMPT SMP
[37012.137567] Modules linked in: btrfs blake2b_generic xor xor_neon 
zstd_compress raid6_pq crct10dif_ce ip_tables x_tables ipv6
[37012.140742] CPU: 0 PID: 289001 Comm: kworker/u64:3 Not tainted 
5.11.0-rc5+ #10
[37012.142839] Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 
02/06/2015
[37012.144787] Workqueue: btrfs-endio btrfs_work_helper [btrfs]
[37012.146474] pstate: 20000005 (nzCv daif -PAN -UAO -TCO BTYPE=--)
[37012.148175] pc : __crc32c_le+0x84/0xe8
[37012.149266] lr : chksum_digest+0x24/0x40
[37012.150420] sp : ffff80001638f8f0
[37012.151491] x29: ffff80001638f8f0 x28: ffff0000c7bb0000
[37012.152982] x27: ffff0000d1a27000 x26: ffff0002f21b56e0
[37012.154565] x25: ffff800011df3948 x24: 0000004000000000
[37012.156063] x23: ffff000000000000 x22: ffff80001638fa00
[37012.157570] x21: 0000000000000004 x20: ffff0000c7bb0050
[37012.159145] x19: ffff80001638fc88 x18: 0000000000000000
[37012.160684] x17: 0000000000000000 x16: 0000000000000000
[37012.162190] x15: 0000051d5454c764 x14: 000000000000017a
[37012.163774] x13: 0000000000000145 x12: 0000000000000001
[37012.165282] x11: 0000000000000000 x10: 00000000000009d0
[37012.166849] x9 : ffff0000ca305564 x8 : 0000000000000000
[37012.168395] x7 : 0000000000000000 x6 : ffff800011f23980
[37012.169883] x5 : 00000000006f6964 x4 : ffff8000105dd7a8
[37012.171476] x3 : ffff80001638fc88 x2 : 0000000000010000
[37012.172997] x1 : bc61d1f66c080000 x0 : 00000000ffffffff
[37012.174642] Call trace:
[37012.175427]  __crc32c_le+0x84/0xe8
[37012.176419]  crypto_shash_digest+0x34/0x58
[37012.177616]  check_compressed_csum+0xd0/0x2b0 [btrfs]
[37012.179160]  end_compressed_bio_read+0xb8/0x308 [btrfs]
[37012.180731]  bio_endio+0x12c/0x1d8
[37012.181712]  end_workqueue_fn+0x3c/0x60 [btrfs]
[37012.183161]  btrfs_work_helper+0xf4/0x5a8 [btrfs]
[37012.184570]  process_one_work+0x1ec/0x4c0
[37012.185727]  worker_thread+0x48/0x478
[37012.186823]  kthread+0x158/0x160
[37012.187768]  ret_from_fork+0x10/0x34
[37012.188791] Code: 9ac55c08 9ac65d08 1a880000 b4000122 (a8c21023)
[37012.190486] ---[ end trace 4f73e813d058b84c ]---
[37019.180684] note: kworker/u64:3[289001] exited with preempt_count 1
---------------

  Could you please take a look?

Thanks, Anand