mm/madvise: add MADV_WILLNEED to process_madvise()

There is a usecase in Android that an app process's memory is swapped out
by process_madvise() with MADV_PAGEOUT, such as the memory is swapped to
zram or a backing device.  When the process is scheduled to running, like
switch to foreground, multiple page faults may cause the app dropped
frames.

To reduce the problem, System Management Software can read-ahead memory
of the process immediately when the app switches to forground.  Calling
process_madvise() with MADV_WILLNEED can meet this need.

Link: https://lkml.kernel.org/r/20210804082010.12482-1-zhangkui@oppo.com
Signed-off-by: zhangkui <zhangkui@oppo.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
zhangkui 2021-09-02 15:01:11 -07:00 committed by Linus Torvalds
parent 33090af973
commit d5fffc5aff

View File

@ -1048,6 +1048,7 @@ process_madvise_behavior_valid(int behavior)
switch (behavior) {
case MADV_COLD:
case MADV_PAGEOUT:
case MADV_WILLNEED:
return true;
default:
return false;