Re: [PATCH v2 1/6] fs/readdir: Fix filldir() and filldir64() use of user_access_begin()

Le 23/01/2020 à 13:00, Michael Ellerman a écrit :

Michael Ellerman [off-list ref] writes:

quoted

Hi Christophe,

This patch is independent of the rest of the series AFAICS

And of course having hit send I immediately realise that's not true.

Without this, book3s/32 fails booting. (And without patch 2, it even hangs, looping forever in do_page_fault()).

quoted

So I'll take patches 2-6 via powerpc and assume this patch will go via
Linus or Al or elsewhere.

So I guess I'll wait and see what happens with patch 1.

We could eventually opt out user_access_begin() for CONFIG_PPC_BOOK3S_32, then you could take patches 3 and 6. That's enough to have user_access_begin() and stuff for 8xx and RADIX.

Patch 2 should be taken as well as a fix, and can be kept independant of the series (once we have patch 1, we normally don't hit the problem fixed by patch 2).

Won't don't need patch 4 until we want user_access_begin() supported by book3s/32


However, I'm about to send out a v3 with a different approach. It modifies the core part where user_access_begin() is returning an opaque value used by user_access_end(). And it also tells user_access_begin() whether it's a read or a write, so that we can limit unlocking to write acccesses on book3s/32, and fine grain rights on book3s/64.

Maybe you would prefer this change on top of first step, in which case I'll be able to make a v4 rebasing all this on top of patch 3 and 6 of v3 series. Tell me what you prefer.

Christophe