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Fix fork-related bugs.

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Acquire/release arena bin locks as part of the prefork/postfork.  This
bug made deadlock in the child between fork and exec a possibility.

Split jemalloc_postfork() into jemalloc_postfork_{parent,child}() so
that the child can reinitialize mutexes rather than unlocking them.  In
practice, this bug tended not to cause problems.
This commit is contained in:
Jason Evans
2012-03-13 16:31:41 -07:00
parent 824d34e5b7
commit 4e2e3dd9cf
13 changed files with 194 additions and 38 deletions
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52
src/jemalloc.c
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@@ -610,8 +610,8 @@ malloc_init_hard(void)
malloc_conf_init();
/* Register fork handlers. */
if (pthread_atfork(jemalloc_prefork, jemalloc_postfork,
jemalloc_postfork) != 0) {
if (pthread_atfork(jemalloc_prefork, jemalloc_postfork_parent,
jemalloc_postfork_child) != 0) {
malloc_write("<jemalloc>: Error in pthread_atfork()\n");
if (opt_abort)
abort();
@@ -1593,40 +1593,46 @@ jemalloc_prefork(void)
unsigned i;
/* Acquire all mutexes in a safe order. */
malloc_mutex_lock(&arenas_lock);
malloc_mutex_prefork(&arenas_lock);
for (i = 0; i < narenas; i++) {
if (arenas[i] != NULL)
malloc_mutex_lock(&arenas[i]->lock);
arena_prefork(arenas[i]);
}
malloc_mutex_lock(&base_mtx);
malloc_mutex_lock(&huge_mtx);
if (config_dss)
malloc_mutex_lock(&dss_mtx);
base_prefork();
huge_prefork();
chunk_dss_prefork();
}
void
jemalloc_postfork(void)
jemalloc_postfork_parent(void)
{
unsigned i;
/* Release all mutexes, now that fork() has completed. */
if (config_dss)
malloc_mutex_unlock(&dss_mtx);
malloc_mutex_unlock(&huge_mtx);
malloc_mutex_unlock(&base_mtx);
chunk_dss_postfork_parent();
huge_postfork_parent();
base_postfork_parent();
for (i = 0; i < narenas; i++) {
if (arenas[i] != NULL)
malloc_mutex_unlock(&arenas[i]->lock);
arena_postfork_parent(arenas[i]);
}
malloc_mutex_unlock(&arenas_lock);
malloc_mutex_postfork_parent(&arenas_lock);
}
void
jemalloc_postfork_child(void)
{
unsigned i;
/* Release all mutexes, now that fork() has completed. */
chunk_dss_postfork_child();
huge_postfork_child();
base_postfork_child();
for (i = 0; i < narenas; i++) {
if (arenas[i] != NULL)
arena_postfork_child(arenas[i]);
}
malloc_mutex_postfork_child(&arenas_lock);
}
/******************************************************************************/