Messages in this thread | | | Date | Sat, 30 Nov 2013 15:56:42 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH] Add a text_poke syscall v2 |
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On 11/29, H. Peter Anvin wrote: > > On 11/29/2013 12:35 PM, Oleg Nesterov wrote: > > On 11/29, H. Peter Anvin wrote: > >> > >> On 11/29/2013 12:05 PM, Oleg Nesterov wrote: > >>> > >>> Can't we invalidate pte (so that any user will stuck in page fault), > >>> update the page(s), restore the pte and drop the locks? > >> > >> That would require a global TLB shootdown > > > > Well, it is not really global, it is for mm_cpumask() and for good > > reason? > > > > And is it really worse than on_each_cpu(do_sync_core) and the usage > > of text_mutex? > > > > Probably not, but one would have to consider the total amount of > synchronization needed.
Yes, agreed, this should be justified.
> >> (and wouldn't help > >> shared-memory code segments, if we care about that at all.) > > > > Well, I think this should only support the private mappings. > > > > Well, what do you do if someone tries this on a MAP_SHARED mapping? > Error out?
Imho yes. But this needs more discussion, and afaics this is a bit offtopic.
Please note that this patch relies on bp_target_mm, this can't help in VM_SHARED case too.
Oleg.
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