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authorAndres Freund2021-09-14 01:07:19 +0000
committerAndres Freund2021-09-14 01:26:15 +0000
commitedb4d95ddf8984ad5b24d964d45884977d2fde4b (patch)
tree7507d785c517ddcf5a4195393481f5ee67cf8100
parent026ed8efd6b1d774924937baf3209b676df4531f (diff)
jit: Do not try to shut down LLVM state in case of LLVM triggered errors.
If an allocation failed within LLVM it is not safe to call back into LLVM as LLVM is not generally safe against exceptions / stack-unwinding. Thus errors while in LLVM code are promoted to FATAL. However llvm_shutdown() did call back into LLVM even in such cases, while llvm_release_context() was careful not to do so. We cannot generally skip shutting down LLVM, as that can break profiling. But it's OK to do so if there was an error from within LLVM. Reported-By: Jelte Fennema <[email protected]> Author: Andres Freund <[email protected]> Author: Justin Pryzby <[email protected]> Discussion: https://postgr.es/m/AM5PR83MB0178C52CCA0A8DEA0207DC14F7FF9@AM5PR83MB0178.EURPRD83.prod.outlook.com Backpatch: 11-, where jit was introduced
-rw-r--r--src/backend/jit/llvm/llvmjit.c18
-rw-r--r--src/backend/jit/llvm/llvmjit_error.cpp10
-rw-r--r--src/include/jit/llvmjit.h1
3 files changed, 27 insertions, 2 deletions
diff --git a/src/backend/jit/llvm/llvmjit.c b/src/backend/jit/llvm/llvmjit.c
index df691cbf1c..169dad96d7 100644
--- a/src/backend/jit/llvm/llvmjit.c
+++ b/src/backend/jit/llvm/llvmjit.c
@@ -172,8 +172,6 @@ llvm_release_context(JitContext *context)
{
LLVMJitContext *llvm_context = (LLVMJitContext *) context;
- llvm_enter_fatal_on_oom();
-
/*
* When this backend is exiting, don't clean up LLVM. As an error might
* have occurred from within LLVM, we do not want to risk reentering. All
@@ -182,6 +180,8 @@ llvm_release_context(JitContext *context)
if (proc_exit_inprogress)
return;
+ llvm_enter_fatal_on_oom();
+
if (llvm_context->module)
{
LLVMDisposeModule(llvm_context->module);
@@ -885,6 +885,20 @@ llvm_session_initialize(void)
static void
llvm_shutdown(int code, Datum arg)
{
+ /*
+ * If llvm_shutdown() is reached while in a fatal-on-oom section an error
+ * has occurred in the middle of LLVM code. It is not safe to call back
+ * into LLVM (which is why a FATAL error was thrown).
+ *
+ * We do need to shutdown LLVM in other shutdown cases, otherwise
+ * e.g. profiling data won't be written out.
+ */
+ if (llvm_in_fatal_on_oom())
+ {
+ Assert(proc_exit_inprogress);
+ return;
+ }
+
#if LLVM_VERSION_MAJOR > 11
{
if (llvm_opt3_orc)
diff --git a/src/backend/jit/llvm/llvmjit_error.cpp b/src/backend/jit/llvm/llvmjit_error.cpp
index 26bc828875..daefb3e1fd 100644
--- a/src/backend/jit/llvm/llvmjit_error.cpp
+++ b/src/backend/jit/llvm/llvmjit_error.cpp
@@ -84,6 +84,16 @@ llvm_leave_fatal_on_oom(void)
}
/*
+ * Are we currently in an fatal-on-oom section? Useful to skip cleanup in case
+ * of errors.
+ */
+bool
+llvm_in_fatal_on_oom(void)
+{
+ return fatal_new_handler_depth > 0;
+}
+
+/*
* Reset fatal error handling. This should only be called in error recovery
* loops like PostgresMain()'s.
*/
diff --git a/src/include/jit/llvmjit.h b/src/include/jit/llvmjit.h
index a8ba5a4fac..3560715e32 100644
--- a/src/include/jit/llvmjit.h
+++ b/src/include/jit/llvmjit.h
@@ -84,6 +84,7 @@ extern LLVMValueRef AttributeTemplate;
extern void llvm_enter_fatal_on_oom(void);
extern void llvm_leave_fatal_on_oom(void);
+extern bool llvm_in_fatal_on_oom(void);
extern void llvm_reset_after_error(void);
extern void llvm_assert_in_fatal_section(void);