Messages in this thread | | | Date | Wed, 2 Aug 2023 17:12:07 +0200 | Subject | Re: [PATCH v2 1/8] mm/gup: reintroduce FOLL_NUMA as FOLL_HONOR_NUMA_FAULT | From | David Hildenbrand <> |
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>> Reported-by: liubo <liubo254@huawei.com> >> Closes: https://lore.kernel.org/r/20230726073409.631838-1-liubo254@huawei.com >> Reported-by: Peter Xu <peterx@redhat.com> >> Closes: https://lore.kernel.org/all/ZMKJjDaqZ7FW0jfe@x1n/ >> Fixes: 474098edac26 ("mm/gup: replace FOLL_NUMA by gup_can_follow_protnone()") >> Cc: <stable@vger.kernel.org> >> Signed-off-by: David Hildenbrand <david@redhat.com> > > I agree that FOLL_REMOTE probably needs separate treatment but also agree > that it's outside the context of this patch, particularly as a -stable > candidate so > > Acked-by: Mel Gorman <mgorman@techsingularity.net> > > I've a minor nit below that would be nice to get fixed up, but not > mandatory.
Thanks Mel for taking a look, so I don't mess up once more :)
> >> --- >> include/linux/mm.h | 21 +++++++++++++++------ >> include/linux/mm_types.h | 9 +++++++++ >> mm/gup.c | 29 +++++++++++++++++++++++------ >> mm/huge_memory.c | 2 +- >> 4 files changed, 48 insertions(+), 13 deletions(-) >> >> diff --git a/mm/gup.c b/mm/gup.c >> index 2493ffa10f4b..f463d3004ddc 100644 >> --- a/mm/gup.c >> +++ b/mm/gup.c >> @@ -2240,6 +2244,12 @@ static bool is_valid_gup_args(struct page **pages, int *locked, >> gup_flags |= FOLL_UNLOCKABLE; >> } >> >> + /* >> + * For now, always trigger NUMA hinting faults. Some GUP users like >> + * KVM really require it to benefit from autonuma. >> + */ >> + gup_flags |= FOLL_HONOR_NUMA_FAULT; >> + >> /* FOLL_GET and FOLL_PIN are mutually exclusive. */ >> if (WARN_ON_ONCE((gup_flags & (FOLL_PIN | FOLL_GET)) == >> (FOLL_PIN | FOLL_GET))) > > Expand on *why* KVM requires it even though I suspect this changes later > in the series. Maybe "Some GUP users like KVM require the hint to be as > the calling context of GUP is functionally similar to a memory reference > from task context"?
It's raised later in this series but it doesn't hurt to discuss it here in a bit more detail.
Sounds good to me.
> > Also minor nit -- s/autonuma/NUMA Balancing/ or numab. autonuma refers to > a specific implementation of automatic balancing that operated similar to > khugepaged but not merged. If you grep for it, you'll find that autonuma > is only referenced in powerpc-specific code. It's not important these > days but very early on, it was very confusing if AutoNUMA was mentioned > when NUMAB was intended.
Ah, yes, thanks. That's the one of the only place where that terminology accidentally slipped in.
I'll wait for more feedback and resend!
-- Cheers,
David / dhildenb
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