diff options
| author | Tom Lane | 2017-09-25 20:09:19 +0000 |
|---|---|---|
| committer | Tom Lane | 2017-09-25 20:09:19 +0000 |
| commit | 899bd785c0edf376077d3f5d65c316f92c1b64b5 (patch) | |
| tree | 36b34442e55b2267f3b93cfc5459b83635bd50cb /src/include | |
| parent | 716ea626a88ac510523ab3af5bc779d78eeced58 (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 2a4e9f6050..39286836dc 100644 --- a/src/include/pg_config.h.in +++ b/src/include/pg_config.h.in @@ -393,6 +393,9 @@ /* 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 the assembler supports PPC's LWARX mutex hint bit. */ #undef HAVE_PPC_LWARX_MUTEX_HINT diff --git a/src/include/pg_config.h.win32 b/src/include/pg_config.h.win32 index b6808d581b..d90f5a6b5b 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 `pstat' function. */ /* #undef HAVE_PSTAT */ |