Messages in this thread | | | From | Mark Gross <> | Subject | Re: PATCH Multithreaded core dump support for the 2.5.14 (and 15) kernel. | Date | Thu, 16 May 2002 14:40:24 -0400 |
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On Thursday 16 May 2002 05:24 pm, Robert Love wrote: > On Thu, 2002-05-16 at 14:32, Alan Cox wrote: > > > For this to happen that semaphore would have to held across > > > schedule()'s. The ONLY place I've seen that in the kernel is > > > set_CPUs_allowed + migration_thread. > > > > The 2.5 kernel is pre-emptible. > > Indeed :) > > But there is plenty of places in the kernel - sans preemption - where we > sleep while holding a semaphore. Was that the original question? If > so, set_cpus_allowed by be one of the few _explicit_ places but we > implicitly sleep holding a semaphore all over. Heck, we use them for > user-space synchronization. > > Robert Love >
The original question was: Couldn't the TCore patch deadlock in elf_core_dump on a semiphore held by a sleeping process that gets placed onto the phantom runque?
So far I can't tell the problem is real or not, but I'm worried :(
I haven't hit any such deadlocks in my stress testing, such as it is. In my review of the code I don't see any obviouse problems dispite the fact that the mmap_sem is explicitly grabbed by elf_core_dump.
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