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| author | Andreas Gruenbacher <agruenba@redhat.com> | 2022-04-15 06:28:51 +0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-05-01 17:22:32 +0200 |
| commit | 6e213bc61446d5aefcedb00251c275e30ce82ab5 (patch) | |
| tree | 1ef9c3317256185048cf8d776abee06ce2c5d630 | |
| parent | d3b744791bf06bc9720bfa36bc1757f25802d68b (diff) | |
| download | linux-6e213bc61446d5aefcedb00251c275e30ce82ab5.tar.gz linux-6e213bc61446d5aefcedb00251c275e30ce82ab5.tar.bz2 linux-6e213bc61446d5aefcedb00251c275e30ce82ab5.zip | |
gup: Introduce FOLL_NOFAULT flag to disable page faults
commit 55b8fe703bc51200d4698596c90813453b35ae63 upstream
Introduce a new FOLL_NOFAULT flag that causes get_user_pages to return
-EFAULT when it would otherwise trigger a page fault. This is roughly
similar to FOLL_FAST_ONLY but available on all architectures, and less
fragile.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | include/linux/mm.h | 3 | ||||
| -rw-r--r-- | mm/gup.c | 4 |
2 files changed, 5 insertions, 2 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h index 90c2d7f3c7a8..04345ff97f8c 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2858,7 +2858,8 @@ struct page *follow_page(struct vm_area_struct *vma, unsigned long address, #define FOLL_FORCE 0x10 /* get_user_pages read/write w/o permission */ #define FOLL_NOWAIT 0x20 /* if a disk transfer is needed, start the IO * and return without waiting upon it */ -#define FOLL_POPULATE 0x40 /* fault in page */ +#define FOLL_POPULATE 0x40 /* fault in pages (with FOLL_MLOCK) */ +#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 */ @@ -943,6 +943,8 @@ static int faultin_page(struct vm_area_struct *vma, /* mlock all present pages, but do not fault in new pages */ if ((*flags & (FOLL_POPULATE | FOLL_MLOCK)) == FOLL_MLOCK) return -ENOENT; + if (*flags & FOLL_NOFAULT) + return -EFAULT; if (*flags & FOLL_WRITE) fault_flags |= FAULT_FLAG_WRITE; if (*flags & FOLL_REMOTE) @@ -2868,7 +2870,7 @@ static int internal_get_user_pages_fast(unsigned long start, if (WARN_ON_ONCE(gup_flags & ~(FOLL_WRITE | FOLL_LONGTERM | FOLL_FORCE | FOLL_PIN | FOLL_GET | - FOLL_FAST_ONLY))) + FOLL_FAST_ONLY | FOLL_NOFAULT))) return -EINVAL; if (gup_flags & FOLL_PIN) |