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| author | Shaohua Li <shli@kernel.org> | 2012-10-09 01:32:19 +0200 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-10-09 09:22:47 +0200 |
| commit | 45cac65b0fcd287ebb877b141d40ba9bbe8e5da7 (patch) | |
| tree | 30ed25c91aaeed153de51a78d171cb14582e383f /arch/m68k/mm | |
| parent | atomic: implement generic atomic_dec_if_positive() (diff) | |
| download | linux-45cac65b0fcd287ebb877b141d40ba9bbe8e5da7.tar.xz linux-45cac65b0fcd287ebb877b141d40ba9bbe8e5da7.zip | |
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/m68k/mm')
| -rw-r--r-- | arch/m68k/mm/fault.c | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c index aeebbb7b30f0..a563727806bf 100644 --- a/arch/m68k/mm/fault.c +++ b/arch/m68k/mm/fault.c @@ -170,6 +170,7 @@ good_area: /* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk * of starvation. */ flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; /* * No need to up_read(&mm->mmap_sem) as we would |