Inadvertent freed storage recovery

Patent metadata

Field	Value
Publication number	US-9047185-B2
Application number	US-201213547659-A
Country	US
Kind code	B2
Filing date	Jul 12, 2012
Priority date	Jul 12, 2012
Publication date	Jun 2, 2015
Grant date	Jun 2, 2015

Abstract

An abnormal termination recovery is performed where storage is referenced shortly after the storage has been freed. More specifically, when storage is freed, and that storage is accessed, an abnormal termination error (e.g., a page translation exception event) occurs due to referencing storage that has not been obtained. When the abnormal termination error occurs, an abnormal termination recovery operation is accessed. The abnormal termination recovery operation scans a history of storage freeing operations (e.g., FREEMAIN operations) to determine whether the storage location accessed by the storage access that caused the abnormal termination error was recently freed from within the same address space. If the storage location was recently freed, then the abnormal termination recovery operation reverses the storage freeing operation by issuing a storage obtaining operation (e.g., a GETMAIN operation) to re-obtain the storage.

First claim

What is claimed is:

1. A method for recovering from an abnormal termination error condition, the method comprising:
detecting when an abnormal termination error condition has occurred;
determining whether the abnormal termination error condition was due to a program referencing storage that has not been obtained;
determining whether the storage that has not been obtained was recently freed storage; and,
reobtaining the recently freed storage when the storage that has not been obtained is recently freed storage; and wherein
the determining whether the storage that has not been obtained was recently freed comprises scanning a history of storage freeing operations; and,
the abnormal termination error comprises a page translation exception event.

2. The method of claim 1 , wherein
the determining whether the storage that has not been obtained was recently freed by scanning a history of storage freeing operations determines whether the storage location accessed by the storage access that caused the abnormal termination error was recently freed from within the same address space.

3. The method of claim 2 , wherein
the storage freeing operations correspond to FREEMAIN operations.

4. The method of claim 1 , further comprising
allowing the program referring storage that has not been obtained to access the storage and to continue execution.

5. The method of claim 1 , further comprising
allowing dump processing to capture information relating to the abnormal termination error, so the error is surfaced and diagnostic work can be taken to permanently correct the error.

6. The method of claim 1 , wherein
the abnormal termination error corresponds to an ABEND operation.

7. A system comprising:
a processor;
a data bus coupled to the processor; and
a computer-usable medium embodying computer program code, the computer-usable medium being coupled to the data bus, the computer program code comprising instructions executable by the processor and configured for:
detecting when an abnormal termination error condition has occurred;
determining whether the abnormal termination error condition was due to a program referencing storage that has not been obtained;
determining whether the storage that has not been obtained was recently freed storage; and,
reobtaining the recently freed storage when the storage that has not been obtained is recently freed storage; and wherein

the determining whether the storage that has not been obtained was recently freed comprises scanning a history of storage freeing operations; and,
the abnormal termination error comprises a page translation exception event.

8. The system of claim 7 , wherein
the determining whether the storage that has not been obtained was recently freed by scanning a history of storage freeing operations determines whether the storage location accessed by the storage access that caused the abnormal termination error was recently freed from within the same address space.

9. The system of claim 8 , wherein
the storage freeing operations correspond to FREEMAIN operations.

10. The system of claim 7 , wherein the computer program code further comprises instructions executable by the processor and configured for
allowing the program referring storage that has not been obtained to access the storage and to continue execution.

11. The system of claim 7 , wherein the computer program code further comprises instructions executable by the processor and configured for:
allowing dump processing to capture information relating to the abnormal termination error, so the error is surfaced and diagnostic work can be taken to permanently correct the error.

12. The system of claim 11 , wherein
the abnormal termination error corresponds to an ABEND operation.

13. A non-transitory computer-usable medium embodying computer program code, the computer program code comprising computer executable instructions configured for:
detecting when an abnormal termination error condition has occurred;
determining whether the abnormal termination error condition was due to a program referencing storage that has not been obtained;
determining whether the storage that has not been obtained was recently freed storage; and,
reobtaining the recently freed storage when the storage that has not been obtained is recently freed storage; and wherein
the determining whether the storage that has not been obtained was recently freed comprises scanning a history of storage freeing operations; and,
the abnormal termination error comprises a page translation exception event.

14. The computer-usable medium of claim 13 , wherein
the determining whether the storage that has not been obtained was recently freed by scanning a history of storage freeing operations determines whether the storage location accessed by the storage access that caused the abnormal termination error was recently freed from within the same address space.

15. The computer-usable medium of claim 14 , wherein
the storage freeing operations correspond to FREEMAIN operations.

16. The computer-usable medium of claim 15 , wherein the computer program code further comprises instructions executable by the processor and configured for:
allowing the program referring storage that has not been obtained to access the storage and to continue execution.

17. The computer-usable medium of claim 13 , wherein the computer program code further comprises instructions executable by the processor and configured for:
allowing dump processing to capture information relating to the abnormal termination error, so the error is surfaced and diagnostic work can be taken to permanently correct the error.

18. The computer-usable medium of claim 17 , wherein
the abnormal termination error corresponds to an ABEND operation.

Assignees

• Erdmann Derek L
• Helak Dustin A
• Reed David C
• Smith Max D
• IBM

Inventors

• Erdmann Derek L
• Helak Dustin A
• Reed David C
• Smith Max D

Classifications

• G06F11/0778

  Dumping, i.e. gathering error/state information after a fault for later diagnosis · CPC title

• G06F11/1415

  at system level · CPC title

• G06F11/0793

  Remedial or corrective actions (recovery from an exception in an instruction pipeline G06F9/3861; by retry G06F11/1402; for recovering from a failure of a protocol instance or entity H04L69/40) · CPC title

• G06F11/0727 Primary

  in a storage system, e.g. in a DASD or network based storage system (drivers for digital recording or reproducing units G06F3/06; circuits for error detection or correction within digital recording or reproducing units G11B20/18; for distributed storage of data in networks, e.g. transport arrangements for network file system [NFS], storage area networks [SAN] or network attached storage [NAS], H04L67/1097) · CPC title