Messages in this thread | | | Date | Fri, 6 Oct 2023 20:53:33 +0200 | Subject | Re: [PATCH v4] mm/thp: fix "mm: thp: kill __transhuge_page_enabled()" | From | David Hildenbrand <> |
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On 25.09.23 22:01, Zach O'Keefe wrote: > The 6.0 commits: > > commit 9fec51689ff6 ("mm: thp: kill transparent_hugepage_active()") > commit 7da4e2cb8b1f ("mm: thp: kill __transhuge_page_enabled()") > > merged "can we have THPs in this VMA?" logic that was previously done > separately by fault-path, khugepaged, and smaps "THPeligible" checks. > > During the process, the semantics of the fault path check changed in two > ways: > > 1) A VM_NO_KHUGEPAGED check was introduced (also added to smaps path). > 2) We no longer checked if non-anonymous memory had a vm_ops->huge_fault > handler that could satisfy the fault. Previously, this check had been > done in create_huge_pud() and create_huge_pmd() routines, but after > the changes, we never reach those routines. > > During the review of the above commits, it was determined that in-tree > users weren't affected by the change; most notably, since the only relevant > user (in terms of THP) of VM_MIXEDMAP or ->huge_fault is DAX, which is > explicitly approved early in approval logic. However, this was a bad > assumption to make as it assumes the only reason to support ->huge_fault > was for DAX (which is not true in general). > > Remove the VM_NO_KHUGEPAGED check when not in collapse path and give > any ->huge_fault handler a chance to handle the fault. Note that we > don't validate the file mode or mapping alignment, which is consistent > with the behavior before the aforementioned commits. > > Fixes: 7da4e2cb8b1f ("mm: thp: kill __transhuge_page_enabled()") > Reported-by: Saurabh Singh Sengar <ssengar@microsoft.com> > Signed-off-by: Zach O'Keefe <zokeefe@google.com> > Cc: Yang Shi <shy828301@gmail.com> > Cc: Matthew Wilcox <willy@infradead.org> > Cc: David Hildenbrand <david@redhat.com> > --- > I've updated the changelog to reflect discussions in [1] -- leaving > ack to David / Matthew on whether to take the patch.
Works for me.
Acked-by: David Hildenbrand <david@redhat.com>
-- Cheers,
David / dhildenb
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