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This is an automatically generated e-mail. To reply, visit:
https://reviews.csiden.org/r/217/
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(Updated May 27, 2015, 12:15 p.m.)
Review request for OpenZFS Developer Mailing List and Matthew Ahrens.
Summary (updated)
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5961 Fix stack overflow and panic on FreeBSD.
Bugs: 5961
https://www.illumos.org/projects/illumos-gate//issues/5961
Repository: illumos-gate
Description
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Do not put zfsvfs_t on the stack. Its size of 7656 bytes consumes too much
stack. Allocate it
temporarily instead.
On FreeBSD the kernel stack size is 16384. Issuing 'zpool create' command
builds a kernel
stack consisting of at least 36 frames, with zfs_create_fs() somewhere in the
middle. If
kernel is compiled with -O0, then stack will be exhausted and kernel panics.
The default
compilation option is -O2, and it doesn't panic yet. But still putting extra
7656 bytes
is risky. If any of the 36 functions is modified to consume a bit more stack,
we will panic
on the default kernel.
Diffs
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usr/src/uts/common/fs/zfs/zfs_znode.c
4664899d13f86f556b71aaca6949448ffd45b0eb
Diff: https://reviews.csiden.org/r/217/diff/
Testing
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With the patch, FreeBSD 11-CURRENT compiled with -O0 doesn't panic on 'zpool
create'.
Thanks,
Gleb Smirnoff
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