Messages in this thread | | | Subject | Re: Do we need to unrevert "fs: do not prefault sys_write() user buffer pages"? | From | Nadav Amit <> | Date | Tue, 22 Jun 2021 11:16:03 -0700 |
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> On Jun 22, 2021, at 11:07 AM, Linus Torvalds <torvalds@linux-foundation.org> wrote: > > On Tue, Jun 22, 2021 at 11:05 AM Matthew Wilcox <willy@infradead.org> wrote: >> >> Huh? Last I checked, the fault_in_readable actually read a byte from >> the page. It has to wait for the read to complete before that can >> happen. > > Yeah, we don't have any kind of async fault-in model. > > I'm not sure how that would even look. I don't think it would > necessarily be *impossible* (special marker in the exception table to > let the fault code know that this is a "prepare" fault), but it would > be pretty challenging.
I did send an RFC some time ago for “prepare” fault, but it the RFC requires some more work.
https://lore.kernel.org/lkml/20210225072910.2811795-1-namit@vmware.com/
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