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authorAndreas Gruenbacher <agruenba@redhat.com>2021-08-17 22:52:08 +0200
committerAndreas Gruenbacher <agruenba@redhat.com>2021-10-24 15:26:05 +0200
commit55b8fe703bc51200d4698596c90813453b35ae63 (patch)
tree9a7f9a0bcf98aea2fe8f3c7dcf483c75ffd6f6ea /mm/gup.c
parent4fdccaa0d184c202f98d73b24e3ec8eeee88ab8d (diff)
gup: Introduce FOLL_NOFAULT flag to disable page faults
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>
Diffstat (limited to 'mm/gup.c')
-rw-r--r--mm/gup.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/mm/gup.c b/mm/gup.c
index 795f15c410cc..e1c7e4bde11f 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -918,6 +918,8 @@ 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)
@@ -2843,7 +2845,7 @@ 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)