Messages in this thread | | | From | Linus Torvalds <> | Date | Tue, 22 Jun 2021 11:32:00 -0700 | Subject | Re: Do we need to unrevert "fs: do not prefault sys_write() user buffer pages"? |
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On Tue, Jun 22, 2021 at 11:23 AM David Howells <dhowells@redhat.com> wrote: > > Probably the most obvious way would be to set a flag in task_struct saying > what you're doing and have the point that would otherwise wait for the page to > become unlocked skip to the fault fixup code if the page is locked after > ->readahead() has been invoked and the flag is set, then use get_user() in > iov_iter_fault_in_readable().
Yeah, the existing user access exception handling code _almost_ handles it, except for one thing: you'd need to have some way to distinguish between "prefetch successful" and "fault failed".
And yeah, I guess it could be a flag in task_struct, but at that point my gag reflex starts acting up.
Linus
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