diff options
author | Shaohua Li <shli@kernel.org> | 2012-10-08 23:32:19 (GMT) |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-10-09 07:22:47 (GMT) |
commit | 45cac65b0fcd287ebb877b141d40ba9bbe8e5da7 (patch) | |
tree | 30ed25c91aaeed153de51a78d171cb14582e383f /arch/s390 | |
parent | e79bee24fd6134f90af4228cfebd010136d67631 (diff) | |
download | linux-45cac65b0fcd287ebb877b141d40ba9bbe8e5da7.tar.xz |
readahead: fault retry breaks mmap file read random detection
.fault now can retry. The retry can break state machine of .fault. In
filemap_fault, if page is miss, ra->mmap_miss is increased. In the second
try, since the page is in page cache now, ra->mmap_miss is decreased. And
these are done in one fault, so we can't detect random mmap file access.
Add a new flag to indicate .fault is tried once. In the second try, skip
ra->mmap_miss decreasing. The filemap_fault state machine is ok with it.
I only tested x86, didn't test other archs, but looks the change for other
archs is obvious, but who knows :)
Signed-off-by: Shaohua Li <shaohua.li@fusionio.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/s390')
-rw-r--r-- | arch/s390/mm/fault.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c index ac9122c..04ad400 100644 --- a/arch/s390/mm/fault.c +++ b/arch/s390/mm/fault.c @@ -367,6 +367,7 @@ retry: /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk * of starvation. */ flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; down_read(&mm->mmap_sem); goto retry; } |