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authorMiles Chen <miles.chen@mediatek.com>2020-06-01 21:48:33 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-02 10:59:08 -0700
commit548b6a1e5520d5647e3d39c0aaf1f83ab27e250f (patch)
tree99317156f9c26f3b88380b6bae3e599f25717fda /mm/gup.c
parente792031019bdc3f1eb5cac5a4171f7ffb8586c1b (diff)
mm/gup.c: further document vma_permits_fault()
Describe the caller's responsibilities when passing FAULT_FLAG_ALLOW_RETRY. Link: http://lkml.kernel.org/r/1586915606.5647.5.camel@mtkswgap22 Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/gup.c')
-rw-r--r--mm/gup.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/gup.c b/mm/gup.c
index c3014669988b..1d84291543fd 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1176,7 +1176,8 @@ static bool vma_permits_fault(struct vm_area_struct *vma,
* @address: user address
* @fault_flags:flags to pass down to handle_mm_fault()
* @unlocked: did we unlock the mmap_sem while retrying, maybe NULL if caller
- * does not allow retry
+ * does not allow retry. If NULL, the caller must guarantee
+ * that fault_flags does not contain FAULT_FLAG_ALLOW_RETRY.
*
* This is meant to be called in the specific scenario where for locking reasons
* we try to access user memory in atomic context (within a pagefault_disable()