Messages in this thread | | | Date | Sat, 30 Nov 2013 16:20:13 +0100 | From | Oleg Nesterov <> | Subject | Re: [PATCH] Add a text_poke syscall v2 |
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On 11/30, Jiri Kosina wrote: > > On Fri, 29 Nov 2013, Oleg Nesterov wrote: > > > > > Andi, et al. I am going to discuss the things I do not really > > > > understand, probably this can't make any sense, but... > > > > > > I think it's enough to set the dirty bit in the underlying > > > struct page, no need to play games with the PTE. > > > > Ah, sorry for confusion, I guess you misunderstood. > > > > I meant, perhaps sys_text_poke() doesn't the in-kernel text_poke > > machinery altogether? > > > > 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? > > Do you think this'd be faster than the int3-based aproach?
No.
And more, I simply do not know if it would be slower or faster, and how much. Just I hope that this won't be "much" slower.
OTOH, this is obviously more scalable, and this way sys_text_poke() won't block, say, jump_label or kprobes. Not sure this actually matters though.
> We have moved from using stop_machine() to int3-based patching exactly > because it's much more lightweight.
Oh, I do not think it makes sense to compare stop_machine() with this approach...
Oleg.
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