diff options
| author | David Hildenbrand <david@redhat.com> | 2022-08-25 18:46:57 +0200 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2022-09-26 19:46:28 -0700 |
| commit | 474098edac262ae26bfab1c48445877075a31cbd (patch) | |
| tree | 4a3e87b877db5029d08b97e814d275d49d38f561 | |
| parent | f7091ed64ec8311b0c35865875f8c3e04e5ea532 (diff) | |
mm/gup: replace FOLL_NUMA by gup_can_follow_protnone()
Patch series "mm: minor cleanups around NUMA hinting".
Working on some GUP cleanups (e.g., getting rid of some FOLL_ flags) and
preparing for other GUP changes (getting rid of FOLL_FORCE|FOLL_WRITE for
for taking a R/O longterm pin), this is something I can easily send out
independently.
Get rid of FOLL_NUMA, allow FOLL_FORCE access to PROT_NONE mapped pages in
GUP-fast, and fixup some documentation around NUMA hinting.
This patch (of 3):
No need for a special flag that is not even properly documented to be
internal-only.
Let's just factor this check out and get rid of this flag. The separate
function has the nice benefit that we can centralize comments.
Link: https://lkml.kernel.org/r/20220825164659.89824-2-david@redhat.com
Link: https://lkml.kernel.org/r/20220825164659.89824-1-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>
| -rw-r--r-- | include/linux/mm.h | 16 | ||||
| -rw-r--r-- | mm/gup.c | 12 | ||||
| -rw-r--r-- | mm/huge_memory.c | 2 |
3 files changed, 18 insertions, 12 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 37384a84f71a..eb25cae06c55 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2933,7 +2933,6 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address, * and return without waiting upon it */ #define FOLL_NOFAULT 0x80 /* do not fault in pages */ #define FOLL_HWPOISON 0x100 /* check page is hwpoisoned */ -#define FOLL_NUMA 0x200 /* force NUMA hinting page fault */ #define FOLL_MIGRATION 0x400 /* wait for page to replace migration entry */ #define FOLL_TRIED 0x800 /* a retry, previous pass started an IO */ #define FOLL_REMOTE 0x2000 /* we are working on non-current tsk/mm */ @@ -3054,6 +3053,21 @@ static inline bool gup_must_unshare(unsigned int flags, struct page *page) return !PageAnonExclusive(page); } +/* + * Indicates whether GUP can follow a PROT_NONE mapped page, or whether + * a (NUMA hinting) fault is required. + */ +static inline bool gup_can_follow_protnone(unsigned int flags) +{ + /* + * FOLL_FORCE has to be able to make progress even if the VMA is + * inaccessible. Further, FOLL_FORCE access usually does not represent + * application behaviour and we should avoid triggering NUMA hinting + * faults. + */ + return flags & FOLL_FORCE; +} + typedef int (*pte_fn_t)(pte_t *pte, unsigned long addr, void *data); extern int apply_to_page_range(struct mm_struct *mm, unsigned long address, unsigned long size, pte_fn_t fn, void *data); @@ -561,7 +561,7 @@ retry: migration_entry_wait(mm, pmd, address); goto retry; } - if ((flags & FOLL_NUMA) && pte_protnone(pte)) + if (pte_protnone(pte) && !gup_can_follow_protnone(flags)) goto no_page; page = vm_normal_page(vma, address, pte); @@ -714,7 +714,7 @@ retry: if (likely(!pmd_trans_huge(pmdval))) return follow_page_pte(vma, address, pmd, flags, &ctx->pgmap); - if ((flags & FOLL_NUMA) && pmd_protnone(pmdval)) + if (pmd_protnone(pmdval) && !gup_can_follow_protnone(flags)) return no_page_table(vma, flags); retry_locked: @@ -1160,14 +1160,6 @@ static long __get_user_pages(struct mm_struct *mm, VM_BUG_ON(!!pages != !!(gup_flags & (FOLL_GET | FOLL_PIN))); - /* - * If FOLL_FORCE is set then do not force a full fault as the hinting - * fault information is unrelated to the reference behaviour of a task - * using the address space - */ - if (!(gup_flags & FOLL_FORCE)) - gup_flags |= FOLL_NUMA; - do { struct page *page; unsigned int foll_flags = gup_flags; diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 135acf87d24d..84bf1d5f6b7e 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1447,7 +1447,7 @@ struct page *follow_trans_huge_pmd(struct vm_area_struct *vma, return ERR_PTR(-EFAULT); /* Full NUMA hinting faults to serialise migration in fault paths */ - if ((flags & FOLL_NUMA) && pmd_protnone(*pmd)) + if (pmd_protnone(*pmd) && !gup_can_follow_protnone(flags)) return NULL; if (!pmd_write(*pmd) && gup_must_unshare(flags, page)) |