mm/munlock: delete munlock_vma_pages_all(), allow oomreap

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munlock_vma_pages_range() will still be required, when munlocking but
not munmapping a set of pages; but when unmapping a pte, the mlock count
will be maintained in much the same way as it will be maintained when
mapping in the pte.  Which removes the need for munlock_vma_pages_all()
on mlocked vmas when munmapping or exiting: eliminating the catastrophic
contention on i_mmap_rwsem, and the need for page lock on the pages.

There is still a need to update locked_vm accounting according to the
munmapped vmas when munmapping: do that in detach_vmas_to_be_unmapped().
exit_mmap() does not need locked_vm updates, so delete unlock_range().

And wasn't I the one who forbade the OOM reaper to attack mlocked vmas,
because of the uncertainty in blocking on all those page locks?
No fear of that now, so permit the OOM reaper on mlocked vmas.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

...

This commit is contained in:

Hugh Dickins 2022-02-14 18:23:29 -08:00 • committed by Matthew Wilcox (Oracle)

parent b67bf49ce7

commit a213e5cf71

5 changed files with 12 additions and 47 deletions

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16

mm/internal.h

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5

mm/madvise.c

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4

mm/mlock.c

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32

mm/mmap.c

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2

mm/oom_kill.c

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