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| author |   David Hildenbrand <david@redhat.com> | 2022-08-25 18:46:58 +0200 |
|---|---|---|
| committer |   Andrew Morton <akpm@linux-foundation.org> | 2022-09-26 19:46:28 -0700 |
| commit | 0cf459866a91c741eb14a92f3633638d1dd9db59 (patch) | |
| tree | 6b3a3ea4d88bb9617a69fbe1bbb68a83f003d728 /mm/gup.c | |
| parent | mm/gup: replace FOLL_NUMA by gup_can_follow_protnone() (diff) | |
| download | linux-dev-0cf459866a91c741eb14a92f3633638d1dd9db59.tar.xz linux-dev-0cf459866a91c741eb14a92f3633638d1dd9db59.zip | |
mm/gup: use gup_can_follow_protnone() also in GUP-fast
There seems to be no reason why FOLL_FORCE during GUP-fast would have to
fallback to the slow path when stumbling over a PROT_NONE mapped page. We
only have to trigger hinting faults in case FOLL_FORCE is not set, and any
kind of fault handling naturally happens from the slow path -- where NUMA
hinting accounting/handling would be performed.
Note that the comment regarding THP migration is outdated: commit
2b4847e73004 ("mm: numa: serialise parallel get_user_page against THP
migration") described that this was required for THP due to lack of PMD
migration entries. Nowadays, we do have proper PMD migration entries in
place -- see set_pmd_migration_entry(), which does a proper
pmdp_invalidate() when placing the migration entry.
So let's just reuse gup_can_follow_protnone() here to make it consistent
and drop the somewhat outdated comments.
Link: https://lkml.kernel.org/r/20220825164659.89824-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/gup.c')
| -rw-r--r-- | mm/gup.c | 14 |
1 files changed, 3 insertions, 11 deletions
@@ -2420,11 +2420,7 @@ static int gup_pte_range(pmd_t pmd, pmd_t *pmdp, unsigned long addr, struct page *page; struct folio *folio; - /* - * Similar to the PMD case below, NUMA hinting must take slow - * path using the pte_protnone check. - */ - if (pte_protnone(pte)) + if (pte_protnone(pte) && !gup_can_follow_protnone(flags)) goto pte_unmap; if (!pte_access_permitted(pte, flags & FOLL_WRITE)) @@ -2808,12 +2804,8 @@ static int gup_pmd_range(pud_t *pudp, pud_t pud, unsigned long addr, unsigned lo if (unlikely(pmd_trans_huge(pmd) || pmd_huge(pmd) || pmd_devmap(pmd))) { - /* - * NUMA hinting faults need to be handled in the GUP - * slowpath for accounting purposes and so that they - * can be serialised against THP migration. - */ - if (pmd_protnone(pmd)) + if (pmd_protnone(pmd) && + !gup_can_follow_protnone(flags)) return 0; if (!gup_huge_pmd(pmd, pmdp, addr, next, flags, |