Bug #12279
closed
::arc_compression_stats generates errors
100%
Description
Running ::arc_compression_stats, it appears to partially fail:
> ::arc_compression_stats mdb: couldn't read arc_buf_hdr_t from ffffff0712c3cec0 Histogram of all compressed buffers. Each bucket represents buffers of size: [2^(n-1)*512, 2^n*512). 1: 11 ** 2: 33 ****** 3: 88 *************** 4: 85 *************** 5: 238 **************************************** 6: 62 *********** 7: 36 ******* 8: 57 ********** Histogram of all uncompressed buffers. Each bucket represents buffers of size: [2^(n-1)*512, 2^n*512). 1: 11 *** 2: 33 ******** 3: 88 ********************* 4: 85 ******************** 5: 61 *************** 6: 170 **************************************** 7: 24 ****** 8: 17 **** 9: 121 *****************************
Related issues
Updated by Jason King almost 4 years ago
- Related to Bug #12028: zfs test mdb_001_pos can fail added
Updated by Jason King almost 4 years ago
The failures are due to the way zfs encryption modified arc_buf_hdr_t. mdb_ctf_vread() assumes that it can always read at least sizeof(target_type) bytes from the target. In the post-zfs encryption world, if the arc buf is unencrypted, the actual allocated size of the arc_buf_hdr_t is less than sizeof (arc_buf_hdr_t) -- the actual size is sizeof (arc_buf_hdr_t) - sizeof (arc_buf_hdr_crypt_t). If the memory where the b_crypt_hdr field resides isn't valid, the mdb_ctf_vread() call will fail.
Updated by Jason King over 3 years ago
To test, I build mdb with the changes, and ran both mdb -k and mdb -k -L proto/*/usr/lib/kvm/amd64 (to use the new zfs mdb module). The unchanged zfs module gives the 'couldn't read arc_buf_hdr_t error', while the fixed version does not produce any errors.
Updated by Electric Monk over 3 years ago
- Status changed from New to Closed
- % Done changed from 0 to 100
git commit f3e1a610966249cf3c18b6f431eef3fac2ed90e4
commit f3e1a610966249cf3c18b6f431eef3fac2ed90e4
Author: Jason King <jason.king@joyent.com>
Date: 2020-03-11T18:05:09.000Z
12279 ::arc_compression_stats generates errors
Reviewed by: Jerry Jelinek <jerry.jelinek@joyent.com>
Approved by: Dan McDonald <danmcd@joyent.com>