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authorShaohua Li <shli@kernel.org>2012-10-08 19:32:19 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-09 03:22:47 -0400
commit45cac65b0fcd287ebb877b141d40ba9bbe8e5da7 (patch)
tree30ed25c91aaeed153de51a78d171cb14582e383f /arch/um/kernel
parente79bee24fd6134f90af4228cfebd010136d67631 (diff)
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/um/kernel')
-rw-r--r--arch/um/kernel/trap.c1
1 files changed, 1 insertions, 0 deletions
diff --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index 0353b98ae35a..0f00e9c82080 100644
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c
@@ -89,6 +89,7 @@ good_area:
89 current->min_flt++; 89 current->min_flt++;
90 if (fault & VM_FAULT_RETRY) { 90 if (fault & VM_FAULT_RETRY) {
91 flags &= ~FAULT_FLAG_ALLOW_RETRY; 91 flags &= ~FAULT_FLAG_ALLOW_RETRY;
92 flags |= FAULT_FLAG_TRIED;
92 93
93 goto retry; 94 goto retry;
94 } 95 }