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| author | Tom Lane <tgl@sss.pgh.pa.us> | 2017-09-25 16:09:19 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2017-09-25 16:09:19 -0400 |
| commit | 899bd785c0edf376077d3f5d65c316f92c1b64b5 (patch) | |
| tree | 36b34442e55b2267f3b93cfc5459b83635bd50cb /src/backend/utils/adt/arrayfuncs.c | |
| parent | 716ea626a88ac510523ab3af5bc779d78eeced58 (diff) | |
| download | postgresql-899bd785c0edf376077d3f5d65c316f92c1b64b5.tar.gz postgresql-899bd785c0edf376077d3f5d65c316f92c1b64b5.zip | |
Avoid SIGBUS on Linux when a DSM memory request overruns tmpfs.
On Linux, shared memory segments created with shm_open() are backed by
swap files created in tmpfs. If the swap file needs to be extended,
but there's no tmpfs space left, you get a very unfriendly SIGBUS trap.
To avoid this, force allocation of the full request size when we create
the segment. This adds a few cycles, but none that we wouldn't expend
later anyway, assuming the request isn't hugely bigger than the actual
need.
Make this code #ifdef __linux__, because (a) there's not currently a
reason to think the same problem exists on other platforms, and (b)
applying posix_fallocate() to an FD created by shm_open() isn't very
portable anyway.
Back-patch to 9.4 where the DSM code came in.
Thomas Munro, per a bug report from Amul Sul
Discussion: https://postgr.es/m/1002664500.12301802.1471008223422.JavaMail.yahoo@mail.yahoo.com
Diffstat (limited to 'src/backend/utils/adt/arrayfuncs.c')
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