On Wed, 2013-04-24 at 22:57 +0200, Zbigniew Jędrzejewski-Szmek wrote: > Hi, > we actually have greedy_realloc to wrap realloc. Using it will simplify things > a bit.
Sure, attached.
>From 29a852ffa7f7084da1edd8c757092417abc5b675 Mon Sep 17 00:00:00 2001 From: Colin Walters <walt...@verbum.org> Date: Wed, 24 Apr 2013 14:17:03 -0400 Subject: [PATCH] coredump: use realloc() loop instead of malloc(768M) I typically run VMs with 1024MiB allocated; systemd is unable to write coredumps in this scenario at all because the default kernel configuration will only overcommit 50% of available RAM. Avoid this failure by using a realloc() loop. See: http://lists.freedesktop.org/archives/systemd-devel/2013-April/010709.html --- src/journal/coredump.c | 41 ++++++++++++++++++++++++++++++----------- 1 files changed, 30 insertions(+), 11 deletions(-) diff --git a/src/journal/coredump.c b/src/journal/coredump.c index 2be6d94..757107d 100644 --- a/src/journal/coredump.c +++ b/src/journal/coredump.c @@ -37,6 +37,8 @@ #include "special.h" #include "cgroup-util.h" +/* Few programs have less than 3MiB resident */ +#define COREDUMP_MIN_START (3*1024*1024) /* Make sure to not make this larger than the maximum journal entry * size. See ENTRY_SIZE_MAX in journald-native.c. */ #define COREDUMP_MAX (768*1024*1024) @@ -103,9 +105,11 @@ int main(int argc, char* argv[]) { uid_t uid; gid_t gid; struct iovec iovec[14]; + size_t coredump_bufsize; + size_t coredump_size; _cleanup_free_ char *core_pid = NULL, *core_uid = NULL, *core_gid = NULL, *core_signal = NULL, *core_timestamp = NULL, *core_comm = NULL, *core_exe = NULL, *core_unit = NULL, - *core_session = NULL, *core_message = NULL, *core_cmdline = NULL, *p = NULL; + *core_session = NULL, *core_message = NULL, *core_cmdline = NULL, *coredump_data = NULL; prctl(PR_SET_DUMPABLE, 0); @@ -234,23 +238,38 @@ int main(int argc, char* argv[]) { goto finish; } - p = malloc(9 + COREDUMP_MAX); - if (!p) { + coredump_size = 0; + coredump_bufsize = COREDUMP_MIN_START + 9; + coredump_data = malloc(coredump_bufsize); + if (!coredump_data) { r = log_oom(); goto finish; } - memcpy(p, "COREDUMP=", 9); + memcpy(coredump_data + coredump_size, "COREDUMP=", 9); + coredump_size += 9; - n = loop_read(STDIN_FILENO, p + 9, COREDUMP_MAX, false); - if (n < 0) { - log_error("Failed to read core dump data: %s", strerror(-n)); - r = (int) n; - goto finish; + for (;;) { + n = loop_read(STDIN_FILENO, coredump_data + coredump_size, + coredump_bufsize - coredump_size, false); + if (n < 0) { + log_error("Failed to read core dump data: %s", strerror(-n)); + r = (int) n; + goto finish; + } else if (n == 0) + break; + + coredump_size += n; + if (coredump_size == coredump_bufsize) { + if (!greedy_realloc(&coredump_data, &coredump_bufsize, coredump_bufsize+1)) { + r = log_oom(); + goto finish; + } + } } - iovec[j].iov_base = p; - iovec[j].iov_len = 9 + n; + iovec[j].iov_base = coredump_data; + iovec[j].iov_len = coredump_size; j++; r = sd_journal_sendv(iovec, j); -- 1.7.1
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