On 02/10, Johannes Weiner wrote:
>
> We had reports of systems deadlocking because
Yes, yes, to some degree I understand why it was done this way. Not
that I understand the details of course. Thanks for your explanations.
> > How can a system call know it should return -ENOMEM if put_user() can
On Fri, Feb 06, 2015 at 09:32:46PM +0100, Oleg Nesterov wrote:
> Add cc's.
>
> On 02/06, Oleg Nesterov wrote:
> >
> > And in fact I think that this is not set_child_tid/etc-specific. Perhaps
> > I am totally confused, but I think that put_user() simply should not fail
> > this way. Say, why a
On Fri, Feb 06, 2015 at 09:32:46PM +0100, Oleg Nesterov wrote:
Add cc's.
On 02/06, Oleg Nesterov wrote:
And in fact I think that this is not set_child_tid/etc-specific. Perhaps
I am totally confused, but I think that put_user() simply should not fail
this way. Say, why a syscall should
On 02/10, Johannes Weiner wrote:
We had reports of systems deadlocking because
Yes, yes, to some degree I understand why it was done this way. Not
that I understand the details of course. Thanks for your explanations.
How can a system call know it should return -ENOMEM if put_user() can only
Add cc's.
On 02/06, Oleg Nesterov wrote:
>
> And in fact I think that this is not set_child_tid/etc-specific. Perhaps
> I am totally confused, but I think that put_user() simply should not fail
> this way. Say, why a syscall should return -EFAULT if memory allocation
> "silently" fails? Confused.
On Fri, Feb 6, 2015 at 10:55 PM, Oleg Nesterov wrote:
> On 02/06, Oleg Nesterov wrote:
>>
>> On 02/06, Konstantin Khlebnikov wrote:
>> >
>> > Whole sequence looks like: task calls fork, glibc calls syscall clone with
>> > CLONE_CHILD_SETTID and passes pointer to TLS THREAD_SELF->tid as argument.
On 02/06, Oleg Nesterov wrote:
>
> On 02/06, Konstantin Khlebnikov wrote:
> >
> > Whole sequence looks like: task calls fork, glibc calls syscall clone with
> > CLONE_CHILD_SETTID and passes pointer to TLS THREAD_SELF->tid as argument.
> > Child task gets read-only copy of VM including TLS. Child
On 02/06, Konstantin Khlebnikov wrote:
>
> Whole sequence looks like: task calls fork, glibc calls syscall clone with
> CLONE_CHILD_SETTID and passes pointer to TLS THREAD_SELF->tid as argument.
> Child task gets read-only copy of VM including TLS. Child calls put_user()
> to handle
Currently kernel ignores put_user() errors when it writes tid for syscall
clone flags CLONE_CHILD_SETTID and CLONE_CHILD_CLEARTID.
Unfortunately this code always worked in this way. We cannot abort syscall
if client tid pointer is invalid.
This patch adds get_user() after failed put_user(): if
On Fri, Feb 6, 2015 at 10:55 PM, Oleg Nesterov o...@redhat.com wrote:
On 02/06, Oleg Nesterov wrote:
On 02/06, Konstantin Khlebnikov wrote:
Whole sequence looks like: task calls fork, glibc calls syscall clone with
CLONE_CHILD_SETTID and passes pointer to TLS THREAD_SELF-tid as argument.
On 02/06, Konstantin Khlebnikov wrote:
Whole sequence looks like: task calls fork, glibc calls syscall clone with
CLONE_CHILD_SETTID and passes pointer to TLS THREAD_SELF-tid as argument.
Child task gets read-only copy of VM including TLS. Child calls put_user()
to handle CLONE_CHILD_SETTID
On 02/06, Oleg Nesterov wrote:
On 02/06, Konstantin Khlebnikov wrote:
Whole sequence looks like: task calls fork, glibc calls syscall clone with
CLONE_CHILD_SETTID and passes pointer to TLS THREAD_SELF-tid as argument.
Child task gets read-only copy of VM including TLS. Child calls
Add cc's.
On 02/06, Oleg Nesterov wrote:
And in fact I think that this is not set_child_tid/etc-specific. Perhaps
I am totally confused, but I think that put_user() simply should not fail
this way. Say, why a syscall should return -EFAULT if memory allocation
silently fails? Confused.
Currently kernel ignores put_user() errors when it writes tid for syscall
clone flags CLONE_CHILD_SETTID and CLONE_CHILD_CLEARTID.
Unfortunately this code always worked in this way. We cannot abort syscall
if client tid pointer is invalid.
This patch adds get_user() after failed put_user(): if
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