mm: revert "vmscan: get_scan_ratio() cleanup"
Shaohua Li reported his tmpfs streaming I/O test can lead to make oom.
The test uses a 6G tmpfs in a system with 3G memory. In the tmpfs, there
are 6 copies of kernel source and the test does kbuild for each copy. His
investigation shows the test has a lot of rotated anon pages and quite few
file pages, so get_scan_ratio calculates percent[0] (i.e. scanning
percent for anon) to be zero. Actually the percent[0] shoule be a big
value, but our calculation round it to zero.
Although before commit 84b18490 ("vmscan: get_scan_ratio() cleanup") , we
have the same problem too. But the old logic can rescue percent[0]==0
case only when priority==0. It had hided the real issue. I didn't think
merely streaming io can makes percent[0]==0 && priority==0 situation. but
I was wrong.
So, definitely we have to fix such tmpfs streaming io issue. but anyway I
revert the regression commit at first.
This reverts commit 84b18490d1f1bc7ed5095c929f78bc002eb70f26.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reported-by: Shaohua Li <shaohua.li@intel.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 file changed