diff options
| author | Tom Lane <tgl@sss.pgh.pa.us> | 2017-09-25 16:09:20 -0400 |
|---|---|---|
| committer | Tom Lane <tgl@sss.pgh.pa.us> | 2017-09-25 16:09:20 -0400 |
| commit | 3a07a6f3e8d204e2141f09c20de4caecd998fa3f (patch) | |
| tree | c5a0d92cb86da1ebf02bf60ed80a3eaf3da92850 /src/include | |
| parent | 9bf04994697dd094032d08682a25cbba7aba523f (diff) | |
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/include')
| -rw-r--r-- | src/include/pg_config.h.in | 3 | ||||
| -rw-r--r-- | src/include/pg_config.h.win32 | 3 |
2 files changed, 6 insertions, 0 deletions
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in index 650f2dceb74..4c8aa0c571b 100644 --- a/src/include/pg_config.h.in +++ b/src/include/pg_config.h.in @@ -365,6 +365,9 @@ /* Define to 1 if you have the `posix_fadvise' function. */ #undef HAVE_POSIX_FADVISE +/* Define to 1 if you have the `posix_fallocate' function. */ +#undef HAVE_POSIX_FALLOCATE + /* Define to 1 if you have the POSIX signal interface. */ #undef HAVE_POSIX_SIGNALS diff --git a/src/include/pg_config.h.win32 b/src/include/pg_config.h.win32 index 60f91056af7..7d403e6fbb2 100644 --- a/src/include/pg_config.h.win32 +++ b/src/include/pg_config.h.win32 @@ -261,6 +261,9 @@ /* Define to 1 if you have the <poll.h> header file. */ /* #undef HAVE_POLL_H */ +/* Define to 1 if you have the `posix_fallocate' function. */ +/* #undef HAVE_POSIX_FALLOCATE */ + /* Define to 1 if you have the POSIX signal interface. */ /* #undef HAVE_POSIX_SIGNALS */ |