Messages in this thread |  | | | Date | Sun, 11 Aug 2002 22:36:50 -0700 | | From | Andrew Morton <> | | Subject | Re: 2.5.31: modules don't work at all |
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Skip Ford wrote: > > ... > > I already know that the error that trips insmod occurs at > > in modules.c, line 831, when qm_symbols gets an error from copy_to_user(): > > > > for (; i < mod->nsyms ; ++i, ++s, vals += 2) { > > len = strlen(s->name)+1; > > if (len > bufsize) > > goto calc_space_needed; > > > > here------> if (copy_to_user(strings, s->name, len) > > || __put_user(s->value, vals+0) > > || __put_user(space, vals+1)) > > return -EFAULT; > > > > strings += len; > > bufsize -= len; > > space += len; > > } > > > > The values of strings and s->name are similar in 2.5.30+preempt > > (works) and 2.5.31+preempt (does not work). strings is 0x08______, and > > s->name is 0xc0______. > > If I back out this change to arch/i386/mm/fault.c then modules > successfully load. I have no idea if backing it out causes other > problems though. > > diff -Nru a/arch/i386/mm/fault.c b/arch/i386/mm/fault.c > --- a/arch/i386/mm/fault.c Sat Aug 10 18:42:20 2002 > +++ b/arch/i386/mm/fault.c Sat Aug 10 18:42:20 2002 > @@ -181,10 +181,10 @@ > info.si_code = SEGV_MAPERR; > > /* > - * If we're in an interrupt or have no user > - * context, we must not take the fault.. > + * If we're in an interrupt, have no user context or are running in an > + * atomic region then we must not take the fault.. > */ > - if (in_interrupt() || !mm) > + if (preempt_count() || !mm) > goto no_context; > > down_read(&mm->mmap_sem); >
Yes, that's the problem. qm_symbols() is performing copy_to_user() inside lock_kernel() and that's an "atomic copy_to_user()" in 2.5.31. But only if preempt is selected. The copy_to_user() doesn't work.
There's nothing illegal about copy_to_user() inside lock_kernel().
Linus, we can back out the preempt_count() test in there and perform the atomic copy_*_user via a current->flags bit, or we can do something else? - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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