diff options
| author |   Shaohua Li <shli@kernel.org> | 2012-10-08 16:32:19 -0700 |
|---|---|---|
| committer |   Linus Torvalds <torvalds@linux-foundation.org> | 2012-10-09 16:22:47 +0900 |
| commit | 45cac65b0fcd287ebb877b141d40ba9bbe8e5da7 (patch) | |
| tree | 30ed25c91aaeed153de51a78d171cb14582e383f /mm | |
| parent | atomic: implement generic atomic_dec_if_positive() (diff) | |
| download | linux-dev-45cac65b0fcd287ebb877b141d40ba9bbe8e5da7.tar.xz linux-dev-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 'mm')
| -rw-r--r-- | mm/filemap.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/filemap.c b/mm/filemap.c index a9827b42556e..83efee76a5c0 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -1607,13 +1607,13 @@ int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf) * Do we have something in the page cache already? */ page = find_get_page(mapping, offset); - if (likely(page)) { + if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) { /* * We found the page, so try async readahead before * waiting for the lock. */ do_async_mmap_readahead(vma, ra, file, page, offset); - } else { + } else if (!page) { /* No page in the page cache at all */ do_sync_mmap_readahead(vma, ra, file, offset); count_vm_event(PGMAJFAULT); |