On Thu, Oct 18, 2018 at 02:17:14PM +1300, Thomas Munro wrote: > On Thu, Oct 18, 2018 at 1:10 PM Tom Lane <t...@sss.pgh.pa.us> wrote: > > ... However, I'm still slightly interested in how it > > was that that broke DSM so thoroughly ... > > Me too. Frustratingly, that vm object might still exist on Larry's > machine if it hasn't been rebooted (since we failed to shm_unlink() > it), so if we knew its name we could write a program to shm_open(), > mmap(), dump out to a file for analysis and then we could work out > which of the sanity tests it failed and maybe get some clues. > Unfortunately it's not in any of our logs AFAIK, and I can't see any > way to get a list of existing shm_open() objects from the kernel. > From sys/kern/uipc_shm.c: > > * TODO: > * > * (1) Need to export data to a userland tool via a sysctl. Should ipcs(1) > * and ipcrm(1) be expanded or should new tools to manage both POSIX > * kernel semaphores and POSIX shared memory be written? > > Gah. So basically that's hiding in shm_dictionary in the kernel and I > don't know a way to look at it from userspace (other than trying to > open all 2^32 random paths we're capable of generating).
It has *NOT* been rebooted. I can give y'all id's if you want to go poking around. > > -- > Thomas Munro > http://www.enterprisedb.com -- Larry Rosenman http://www.lerctr.org/~ler Phone: +1 214-642-9640 E-Mail: l...@lerctr.org US Mail: 5708 Sabbia Drive, Round Rock, TX 78665-2106
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