Hi, I believe we have a case where not holding off interrupts while doing a malloc() can cause a deadlock due to system or libc level locking. In this case, a pg_ctl stop in fast mode was resorted to and that caused a backend to handle the interrupt when it was inside the malloc call. Now as part of the abort processing, in the subtransaction cleanup code path, this same backend tried to clear memory contexts, leading to an eventual free() call. The free() call tried to take the same lock which was already held by malloc() earlier resulting into a deadlock! Will try to get the call stack if needed.
The malloc/free functions are known to be not re-entrant. Doesn't it make sense to hold off interrupts while doing such calls inside the AllocSet* set of functions? Thankfully the locations are not very many. AllocSetContextCreate, AllocSetAlloc and AllocSetFree seem to be the only candidates. Comments, thoughts? Regards, Nikhils
