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>
This commit is contained in:
Miles Chen 2020-06-01 21:48:33 -07:00 committed by Linus Torvalds
parent e792031019
commit 548b6a1e55

View File

@ -1176,7 +1176,8 @@ static bool vma_permits_fault(struct vm_area_struct *vma,
* @address: user address * @address: user address
* @fault_flags:flags to pass down to handle_mm_fault() * @fault_flags:flags to pass down to handle_mm_fault()
* @unlocked: did we unlock the mmap_sem while retrying, maybe NULL if caller * @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 * 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() * we try to access user memory in atomic context (within a pagefault_disable()