Messages in this thread | | | Date | Thu, 7 Feb 2019 11:25:55 -0800 | From | Davidlohr Bueso <> | Subject | Re: [PATCH 2/2] MIPS/c-r4k: do no use mmap_sem for gup_fast() |
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On Thu, 07 Feb 2019, Paul Burton wrote:
>Hi Davidlohr, > >On Wed, Feb 06, 2019 at 09:37:40PM -0800, Davidlohr Bueso wrote: >> It is well known that because the mm can internally >> call the regular gup_unlocked if the lockless approach >> fails and take the sem there, the caller must not hold >> the mmap_sem already. >> >> Fixes: e523f289fe4d (MIPS: c-r4k: Fix sigtramp SMP call to use kmap) >> Cc: Ralf Baechle <ralf@linux-mips.org> >> Cc: Paul Burton <paul.burton@mips.com> >> Cc: James Hogan <jhogan@kernel.org> >> Cc: linux-mips@vger.kernel.org >> Signed-off-by: Davidlohr Bueso <dbueso@suse.de> > >Thanks - this looks good, but: > > 1) The problem it fixes was introduced in v4.8. > > 2) Commit adcc81f148d7 ("MIPS: math-emu: Write-protect delay slot > emulation pages") actually left flush_cache_sigtramp unused, and has > been backported to stable kernels also as far as v4.8. > >Therefore this will just fix code that never gets called, and I'll go >delete the whole thing instead.
Even better.
Thanks, Davidlohr
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