zfs/module/os/linux/spl
Matthew Ahrens bbcec73783
kmem_alloc(KM_SLEEP) should use kvmalloc()
`kmem_alloc(size>PAGESIZE, KM_SLEEP)` is backed by `kmalloc()`, which
finds contiguous physical memory.  If there isn't enough contiguous
physical memory available (e.g. due to physical page fragmentation), the
OOM killer will be invoked to make more memory available.  This is not
ideal because processes may be killed when there is still plenty of free
memory (it just happens to be in individual pages, not contiguous runs
of pages).  We have observed this when allocating the ~13KB `zfs_cmd_t`,
for example in `zfsdev_ioctl()`.

This commit changes the behavior of
`kmem_alloc(size>PAGESIZE, KM_SLEEP)` when there are insufficient
contiguous free pages.  In this case we will find individual pages and
stitch them together using virtual memory.  This is accomplished by
using `kvmalloc()`, which implements the described behavior by trying
`kmalloc(__GFP_NORETRY)` and falling back on `vmalloc()`.

The behavior of `kmem_alloc(KM_NOSLEEP)` is not changed; it continues to
use `kmalloc(GPF_ATOMIC | __GFP_NORETRY)`.  This is because `vmalloc()`
may sleep.

Reviewed-by: Tony Nguyen <tony.nguyen@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: George Wilson <gwilson@delphix.com>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes #11461
2021-04-06 12:44:54 -07:00
..
Makefile.in Add zfs_file_* interface, remove vnodes 2019-11-21 09:32:57 -08:00
README.md Replace ZFS on Linux references with OpenZFS 2020-10-08 20:10:13 -07:00
THIRDPARTYLICENSE.gplv2 OpenZFS restructuring - move platform specific sources 2019-09-06 11:26:26 -07:00
THIRDPARTYLICENSE.gplv2.descrip OpenZFS restructuring - move platform specific sources 2019-09-06 11:26:26 -07:00
spl-atomic.c Replace ZFS on Linux references with OpenZFS 2020-10-08 20:10:13 -07:00
spl-condvar.c Replace ZFS on Linux references with OpenZFS 2020-10-08 20:10:13 -07:00
spl-cred.c Replace ZFS on Linux references with OpenZFS 2020-10-08 20:10:13 -07:00
spl-err.c Replace ZFS on Linux references with OpenZFS 2020-10-08 20:10:13 -07:00
spl-generic.c cppcheck: integrete cppcheck 2021-01-26 16:12:26 -08:00
spl-kmem-cache.c Replace ZFS on Linux references with OpenZFS 2020-10-08 20:10:13 -07:00
spl-kmem.c kmem_alloc(KM_SLEEP) should use kvmalloc() 2021-04-06 12:44:54 -07:00
spl-kstat.c cppcheck: return value always 0 2021-01-26 16:12:18 -08:00
spl-proc.c Replace ZFS on Linux references with OpenZFS 2020-10-08 20:10:13 -07:00
spl-procfs-list.c Fix buggy procfs_list_seq_next warning 2020-09-30 13:27:51 -07:00
spl-taskq.c cppcheck: remove redundant ASSERTs 2021-01-26 16:12:10 -08:00
spl-thread.c Replace ZFS on Linux references with OpenZFS 2020-10-08 20:10:13 -07:00
spl-trace.c Add tracepoints for taskq entry lifetime events 2019-11-01 13:14:54 -07:00
spl-tsd.c Replace ZFS on Linux references with OpenZFS 2020-10-08 20:10:13 -07:00
spl-vmem.c Replace ZFS on Linux references with OpenZFS 2020-10-08 20:10:13 -07:00
spl-xdr.c Replace ZFS on Linux references with OpenZFS 2020-10-08 20:10:13 -07:00
spl-zlib.c Replace ZFS on Linux references with OpenZFS 2020-10-08 20:10:13 -07:00

README.md

The Solaris Porting Layer, SPL, is a Linux kernel module which provides a compatibility layer used by the OpenZFS project.

Installation

The latest version of the SPL is maintained as part of this repository. Only when building ZFS version 0.7.x or earlier must an external SPL release be used. These releases can be found at:

Release

The SPL is released under a GPLv2 license.
For more details see the NOTICE and THIRDPARTYLICENSE files; UCRL-CODE-235197