FreeBSD src
13312e2fa1
We've had cases where we trigger an OOM despite having memory freely
available on the system. For example, here, we had about 21GB free:
kernel: Node 0 Normal: 2418758*4kB (UME) 1549533*8kB (UE) 0*16kB
0*32kB 0*64kB 0*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB =
22071296kB
The problem being, all the memory is in 4K and 8K contiguous regions,
but the allocation request was for a 16K contiguous region:
kernel: SafeExecutors-4 invoked oom-killer:
gfp_mask=0x42dc0(GFP_KERNEL|__GFP_NOWARN|__GFP_COMP|__GFP_ZERO),
order=2, oom_score_adj=0
The offending allocation came from this call trace:
kernel: Call Trace:
kernel: dump_stack+0x57/0x7a
kernel: dump_header+0x4f/0x1e1
kernel: oom_kill_process.cold.33+0xb/0x10
kernel: out_of_memory+0x1ad/0x490
kernel: __alloc_pages_slowpath+0xd55/0xe40
kernel: __alloc_pages_nodemask+0x2df/0x330
kernel: kmalloc_large_node+0x42/0x90
kernel: __kmalloc_node+0x25a/0x320
kernel: ? spl_kmem_free_impl+0x21/0x30 [spl]
kernel: spl_kmem_alloc_impl+0xa5/0x100 [spl]
kernel: spl_kmem_zalloc+0x19/0x20 [spl]
kernel: zfsdev_ioctl+0x2b/0xe0 [zfs]
kernel: do_vfs_ioctl+0xa9/0x640
kernel: ? __audit_syscall_entry+0xdd/0x130
kernel: ksys_ioctl+0x67/0x90
kernel: __x64_sys_ioctl+0x1a/0x20
kernel: do_syscall_64+0x5e/0x200
kernel: entry_SYSCALL_64_after_hwframe+0x44/0xa9
kernel: RIP: 0033:0x7fdca3674317
The problem is, for each ioctl that ZFS makes, it has to allocate a
zfs_cmd_t structure, which is 13744 bytes in size (on my system):
sdb> sizeof zfs_cmd
(size_t)13744
This size, coupled with the fact that we currently allocate it with
kmem_zalloc, means we need a 16K contiguous region of memory to satisfy
the request.
The solution taken by this change, is to use "vmem" instead of "kmem" to
do the allocation, such that we don't necessarily need a contiguous 16K
memory region to satisfy the allocation.
Arguably, a better solution would be not to require such a large
allocation to begin with (e.g. reduce the size of the zfs_cmd_t
structure), but that'd be a much larger change than this "one liner".
Thus, I've opted for this approach for now; we can always circle back
and attempt to reduce the size of the structure in the future.
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Reviewed-by: Mark Maybee <mark.maybee@delphix.com>
Reviewed-by: Don Brady <don.brady@delphix.com>
Signed-off-by: Prakash Surya <prakash.surya@delphix.com>
Closes #14474
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| contrib | ||
| etc | ||
| include | ||
| lib | ||
| man | ||
| module | ||
| rpm | ||
| scripts | ||
| tests | ||
| udev | ||
| .editorconfig | ||
| .gitignore | ||
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| autogen.sh | ||
| CODE_OF_CONDUCT.md | ||
| configure.ac | ||
| copy-builtin | ||
| COPYRIGHT | ||
| LICENSE | ||
| Makefile.am | ||
| META | ||
| NEWS | ||
| NOTICE | ||
| README.md | ||
| RELEASES.md | ||
| TEST | ||
| zfs.release.in | ||
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.
Official Resources
- Documentation - for using and developing this repo
- ZoL Site - Linux release info & links
- Mailing lists
- OpenZFS site - for conference videos and info on other platforms (illumos, OSX, Windows, etc)
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
METAfile contains the officially recognized supported Linux kernel versions. - Supported FreeBSD versions are any supported branches and releases starting from 12.2-RELEASE.