Messages in this thread Patch in this message | | | Date | Fri, 02 Oct 2009 16:38:59 -0700 | From | Darren Hart <> | Subject | Re: futex question |
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Anirban Sinha wrote: >> Should we not just clear the pointer (and >>> it's compat version) within do_execve()? > > > In our private repository, applying the following patch resolved the > issues I mentioned. I no longer see messages like this: > > [futex] ("ifconfig")(pid=2509) exit_robust_list:unable to fetch robust > entry. uaddr=0x000000002abbc4f0 > > from my instrumented kernel within exit_robust_list(). My > instrumentation looked something like this:
> > if (fetch_robust_entry(...)) { > printk(...); > return; > } > > Just tossing the patch in the community in case someone is interested
Thanks for sending the patch. I'm looking into it now. Couple questions:
1) What caused you to instrument this path in the first place? Were you seeing some unexpected behavior?
2) I wonder why we would need to clear the robust list, but I don't see other things like pi_blocked_on, etc. in execve being cleared. I'm looking into this now (perhaps we don't do the same cleanup, need to check).... have to get on the plane...
-- Darren Hart
> ... > > > > Signed-off-by: Anirban Sinha <asinha@zeugmasystems.com> > --- > fs/compat.c | 3 +++ > fs/exec.c | 3 +++ > 2 files changed, 6 insertions(+), 0 deletions(-) > > diff --git a/fs/compat.c b/fs/compat.c > index 6d6f98f..c3d117c 100644 > --- a/fs/compat.c > +++ b/fs/compat.c > @@ -1510,6 +1510,9 @@ int compat_do_execve(char * filename, > if (retval) > goto out_file; > > +#ifdef CONFIG_FUTEX > + current->compat_robust_list = NULL; > +#endif > bprm->argc = compat_count(argv, MAX_ARG_STRINGS); > if ((retval = bprm->argc) < 0) > goto out; > diff --git a/fs/exec.c b/fs/exec.c > index 172ceb6..e9334b8 100644 > --- a/fs/exec.c > +++ b/fs/exec.c > @@ -1323,6 +1323,9 @@ int do_execve(char * filename, > retval = bprm_mm_init(bprm); > if (retval) > goto out_file; > +#ifdef CONFIG_FUTEX > + current->robust_list = NULL; > +#endif > > bprm->argc = count(argv, MAX_ARG_STRINGS); > if ((retval = bprm->argc) < 0) > >
-- Darren Hart IBM Linux Technology Center Real-Time Linux Team
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