[v2,0/1] mm/gup: avoid an unnecessary allocation call for FOLL_LONGTERM cases

Message

John Hubbard Nov. 5, 2024, 3:29 a.m. UTC

This applies to today's mm-hotfixes-unstable (only). In order to test
this, my earlier patch is a prequisite: commit 255231c75dcd ("mm/gup:
stop leaking pinned pages in low memory conditions").

Changes since v1 [1]:

1) Completely different implementation: instead of changing the
allocator from kmalloc() to kvmalloc(), just avoid allocations entirely.

Note that David's original suggestion [2] included something that I've
left out for now, mostly because it's a pre-existing question and
deserves its own patch. But also, I don't understand it yet, either.


[1] https://lore.kernel.org/[e-mail]

[2] https://lore.kernel.org/[e-mail]


thanks,
John Hubbard

Cc: David Hildenbrand <[e-mail]>
Cc: Vivek Kasireddy <[e-mail]>
Cc: Dave Airlie <[e-mail]>
Cc: Gerd Hoffmann <[e-mail]>
Cc: Matthew Wilcox <[e-mail]>
Cc: Christoph Hellwig <[e-mail]>
Cc: Jason Gunthorpe <[e-mail]>
Cc: Peter Xu <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: Daniel Vetter <[e-mail]>
Cc: Dongwon Kim <[e-mail]>
Cc: Hugh Dickins <[e-mail]>
Cc: Junxiao Chang <[e-mail]>
Cc: Mike Kravetz <[e-mail]>
Cc: Oscar Salvador <[e-mail]>
Cc: [e-mail]

John Hubbard (1):
  mm/gup: avoid an unnecessary allocation call for FOLL_LONGTERM cases

 mm/gup.c | 116 ++++++++++++++++++++++++++++++++++++-------------------
 1 file changed, 77 insertions(+), 39 deletions(-)


base-commit: 0012ab094cad019afcd07bdfc28e2946537e715c