[0/3] Fix zone revalidation memory allocation failures

Message

Damien Le Moal June 25, 2019, 2:46 a.m. UTC

This series addresses a reccuring problem with zone revalidation
failures observed during extensive testing with memory constrained
system and device hot-plugging.

The problem source is failure to allocate large memory areas with
alloc_pages() or kmalloc() in blk_revalidate_disk_zones() to store the
disk array of zones (struct blk_zone) or in sd_zbc_report_zones() for
the report zones command reply buffer.

The solution proposed here is to:
1) limit the number of zones to be reported with a single report zones
command execution, and
2) Use vmalloc to allocate large-ish arrays and buffers in place of
alloc_pages() and kmalloc().

With these changes, tests do not show any zone revalidation failures
while not impacting the time taken for a disk initial zone inspection
during device scan.

Damien Le Moal (3):
  block: Allow mapping of vmalloc-ed buffers
  sd_zbc: Fix report zones buffer allocation
  block: Limit zone array allocation size

 block/bio.c            |  8 ++++-
 block/blk-zoned.c      | 29 +++++++---------
 drivers/scsi/sd_zbc.c  | 79 +++++++++++++++++++++++++++++++-----------
 include/linux/blkdev.h |  5 +++
 4 files changed, 84 insertions(+), 37 deletions(-)