Here's what happened: Apar: OA41307 Abstract: FORK FAILURE WHEN ADDRESS SPACE OWNS 1MEG PAGES Closed Date: 13/02/23 RSM support for FORK copies high virtual memory objects from the parent address space to the child as part of duplicating the parent process' address space. However, the request currently fails if the parent process owns high virtual that consists of one megabyte pages.
PROBLEM CONCLUSION: TEMPORARY FIX: ********* * HIPER * ********* COMMENTS: All pageable 1M pages in the parent address space will be demoted to 4k pages and copied into the child address space. The easiest and safest solution for the APAR was to simply demote the source 1MB pages so the the existing code could then handle them. Over the years, RSM has changed other functions to reduce the number of cases where demotion is done. For example, z/OS 2.2 avoids demotion when possible for PGSER FIX. and z/OS 2.3 tries to avoid demotion when IARV64 PAGEFIX fixes a portion of a 1MB page. Unfortunately, ForkCopy slipped through the cracks. As a result of your question, it is being added to the list of things to look at for a future release. Jim Mulder z/OS Diagnosis, Design, Development, Test IBM Corp. Poughkeepsie NY "IBM Mainframe Discussion List" <IBM-MAIN@LISTSERV.UA.EDU> wrote on 06/02/2021 04:49:14 PM: > From: "Crawford, Robert C." <000001feadb2c2d2-dmarc-requ...@listserv.ua.edu> > To: IBM-MAIN@LISTSERV.UA.EDU > Date: 06/02/2021 10:35 PM > Subject: Re: EXTERNAL: Re: Why Would COPYSRVH Cause a 1M Page > Demtion [Internal] > Sent by: "IBM Mainframe Discussion List" <IBM-MAIN@LISTSERV.UA.EDU> > > Here is the full trace. I'll gladly accept any help in interpreting. > > Sorry about the bad formatting. > > SYS5 SGTDEM64 00000063 12:44:53.270019 Demote 1M 64 bit page > FUNC1... COPYSRVH High Virtual Copy Service > JOBN1... ZUMCCMG1 ASID1... 0215 PLOCKS.. 8800C001 CPU..... > 0006 > JOBN2... ZUMCCMG3 ASID2... 022D RLOCKS.. 8800C001 RLOCKDET > 0800 ADASID.. 0215 XMASID.. 022D CMASID.. 0000 > STASID.. 0000 > KEY..... 0036 ADDR.... 035E1008 ALET.... 00000000 > 70207520 C710 > KEY..... 009A ADDR.... 035E22B0 ALET.... 00000000 > 035E22F8 00000000 00000000 00000000 00000000 00000000 01000000 > 00000000 00000000 00000000 00000000 00000000 00000000 00000000 > 00000000 00000000 00000000 > 00000000 > KEY..... 009B ADDR.... 035E22F8 ALET.... 00000000 > 00000001 01000003 7FF74D38 04134B00 0000003B E5398D00 00000000 > 00000000 00000000 00000000 00000050 1A000000 00000000 00000000 > 00000000 00000000 00000000 > 00000000 > > > Robert Crawford > Mainframe Management > United Services Automobile Association > (210) 913-3822 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
