Matthew Ahrens a724db0374
Channel program may spuriously fail with "memory limit exhausted"
ZFS channel programs (invoked by `zfs program`) are executed in a LUA
sandbox with a limit on the amount of memory they can consume.  The
limit is 10MB by default, and can be raised to 100MB with the `-m` flag.
If the memory limit is exceeded, the LUA program exits and the command
fails with a message like `Channel program execution failed: Memory
limit exhausted.`

The LUA sandbox allocates memory with `vmem_alloc(KM_NOSLEEP)`, which
will fail if the requested memory is not immediately available.  In this
case, the program fails with the same message, `Memory limit exhausted`.
However, in this case the specified memory limit has not been reached,
and the memory may only be temporarily unavailable.

This commit changes the LUA memory allocator `zcp_lua_alloc()` to use
`vmem_alloc(KM_SLEEP)`, so that we won't spuriously fail when memory is
temporarily low.  Instead, we rely on the system to be able to free up
memory (e.g. by evicting from the ARC), and we assume that even at the
highest memory limit of 100MB, the channel program will not truly
exhaust the system's memory.

External-issue: DLPX-71924
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Matthew Ahrens <mahrens@delphix.com>
Closes #11190
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OpenZFS is an advanced file system and volume manager which was originally developed for Solaris and is now maintained by the OpenZFS community. This repository contains the code for running OpenZFS on Linux and FreeBSD.

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Official Resources

Installation

Full documentation for installing OpenZFS on your favorite operating system can be found at the Getting Started Page.

Contribute & Develop

We have a separate document with contribution guidelines.

We have a Code of Conduct.

Release

OpenZFS is released under a CDDL license. For more details see the NOTICE, LICENSE and COPYRIGHT files; UCRL-CODE-235197

Supported Kernels

  • The META file contains the officially recognized supported Linux kernel versions.
  • Supported FreeBSD versions are 12-STABLE and 13-CURRENT.
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freebsd with flexible iflib nic queues
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