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Re: [LMDB] Lockups with robust mutexes and crashing processes

Marcos-David Dione wrote:
Marcos-David Dione/NCE/AMADEUS wrote on 24/11/2014 11:10:42:
 >         Seen like that I'm not sure if there's a defined behaviour
 > for that. I'll ask in the glibc and/or kernel MLs and I'll come
 > back with the answer.

         and here's the answer:

 > On 11/24/2014 03:34 PM, Marcos Dione wrote:
 > >         We found a situation where a robust mutex cannot be recovered
 > > from a stale lock and we're wondering if it's simply an undefined
 > > situation or  a bug in the kernel. Attached you will find the sample
 > > code, which is loosely based on a glibc's test case.The gist of it
is as
 > > follows:
 > >
 > > 1. we open a file.
 > > 2. we mmap it and use that mem to store a robust mutex.
 > > 3. we lock the mutex.
 > > 4. we munmap the file.
 > > 5. we close the file.
 > Undefined behaviour.
 > This results in undefined behaviour since the allocated storage for
 > the mutex object has been lost. You need to keep that storage around
 > for the robust algorithms to work with. Without any data you can't
 > do anything.

         Full answer:


Fyi, this would not have been a bug in Solaris:


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