Messages in this thread | | | Date | Fri, 13 Mar 2015 16:04:17 +0100 | From | Oleg Nesterov <> | Subject | Re: vvar, gup && coredump |
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On 03/13, Sergio Durigan Junior wrote: > > On Thursday, March 12 2015, Oleg Nesterov wrote: > > > And it seems that we all agree that the kernel should not dump this vma > > too. Could you confirm that this is fine from gdb pov just in case? > > Yes, this is what we expect from the GDB side. This mapping is marked > as "dd", so it does not make sense to dump it.
OK.
> While I have you guys, would it be possible for the Linux kernel to > include a new flag on VmFlags to uniquely identify an anonymous mapping?
Note that "anonymous" is not the right term here... I mean it is a bit confusing. Lets discuss this again on debug-list, then we will see if gdb needs more info from kernel.
> Currently, there is no easy way to do that from userspace. My patch > implements the following heuristic on GDB: > > if (pathname == "/dev/zero (deleted)" > || pathname == "/SYSV%08x (deleted)" > || pathname == "<file> (deleted)"
And for example, this is not anonymous mapping. But,
> mapping is anonymous;
I agree, gdb should treat it as anonymous.
> However, this can be fragile. The Linux kernel checks for i_nlink == 0,
Yes, as we already disccussed, I think the kernel should be changed.
It should do something like shmem_mapping() || d_unlinked(), I think. But this needs another discussion on lkml, and in another thread.
Oleg.
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